Sean Buick 76
I'm Awesome
Good luck on the project I like seeing different stuff!
Slow Roller
- Thread starter nineno
- Start date
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nineno
Newbie
Since I had to hunt around a bit to find the information detailed below, I figured I would dedicate one entry in this build thread to the topic of flywheels, starters, and starter bolts.
If that sounds less interesting than watching paint dry, I won’t be offended if you back out of this posting or close your browser.
The LT1 I’m working with is from a 1995 Corvette. It would seem to be reasonable to start with a flywheel from a 1995 Corvette for whatever manual transmission I’m going to work with. However, that would be a mistake.
The 1995 Corvette came with a ZF 6-speed (ZF-6) which has a clutch setup different than…well, any other GM vehicle.
From corvetteforum.com which is purportedly quoting (or at least relaying) information from a June 2000 issue of Car Craft magazine:
"Used exclusively in 89-96 Corvettes, the ZF six-speed is a massive, durable, and expensive transmission. Rebuild parts are hard to come by. (Vette warranties required trading in a bad trans to GM for a re-manufactured unit.) The ZF shares no common dimensions with traditional GM manual transmissions. Its nonstandard bellhousing accepts a Vette-only pull-style hydraulic clutch. Versions used behind the LT1/LT4 and DOHC LT5 engines have different length input shafts. GM uses a dual-mass flywheel to reduce noise from this massive, truck-like trans."
The up-shot of these details is that the ZF-6/Vette flywheel (dual-mass or otherwise) is also somewhere around 0.150” thinner than a conventional GM flywheel.
Another reasonable approach would seem to be using an F-Body flywheel. However, the 4th Gen F-bodies use a reverse clutch disc (where the compensator springs are closer to the crankshaft, rather than the conventional setup where the are closer to the transmission) so that the pressure plate and bellhousing can be slightly shorter (fore/aft). The narrow pressure plate assembly and shorter bellhousing necessitated the use of a (hydraulically actuated) fork and throwout bearing, and again, make total stack-up more mysterious than it needs to be for my build.
I definitely was not going to try to use a C4 ZF-6 or an 4th Gen F-body T56 transmission, so while the above information was interesting to me, the major revelation was: Don't use flywheels meant for those applications.
Another consideration was the use of the 153T flywheel versus the 168T flywheel. In a smaller/lighter car (Corvette, modern-ish F-Body), the smaller, lighter, lower inertia flywheel makes sense. Likewise, if you've built a high-revving, high powered engine, low-inertia flywheels make sense.
On a modestly-powered V8, with a 'normal' (5500rpm) redline, in a full-size pick-up (albeit a light version of a full-size pick-up), having a bit more inertia (heavier and/or larger diameter) flywheel isn’t an awful idea.
In fact, in one of my exchanges with the fine folks at Ram Clutch, they said that for a street-driven vehicle (classic muscle car, full-size cruiser, certainly a truck), the 168T flywheel is the better bet. Opinions will differ, but I found the input from a flywheel and clutch manufacturer helpful and reassuring.
This took me down the path of looking at truck flywheels for 1-piece rear main seal (1986 and newer) engines. Ultimately, I chose a cast iron, stock replacement style 168T flywheel. These use standard GM stack-up dimensions for clutch, pressure plate assemblies, and bellhousings.
The exact flywheel I bought weighed about 29-pounds, but the mass is decidedly located around the perimeter near the ring gear. (I find it interesting that the inertia of the flywheel under standard test conditions is usually hard to find.)
With the flywheel sorted out, I turned my attention to the starter.
As noted previously, the guy I bought the engine from kept the original Vette starter and gave me a MT-style starter with the engine.
The good news, I suppose, is that the MT-style has the staggered mounting holes indicating that it’s meant for a 168T flywheel. Also good news: I confirmed that it works.
However, I was unconvinced that using this monstrous starter was necessary, or even well-informed. While there is plenty of space in the engine bay of a full-size GM truck, the 10MT starter could only make exhaust routing (as an example) more difficult in the future.
Somewhat later in the assembly process I came to find out that the 10MT starter that I had would not work with the manual transmission bellhousing I selected. This is because the starter has a large cast aluminum “drive-end frame” (let’s just call it the nose cone) that supports the pinion shaft. This starter is usually only compatible with the starter pocket on automatic transmission cases. So, unless I wanted to grind off part of the nose cone of the starter, or hog out some of my brand new bellhousing with a die grinder, I had to get a different starter anyway.
There is an MT-style direct drive starter that was used on manual transmission starters into the early 1980s that I believe would work. For example, AC Delco 3361870 (shown below). This starter features a smaller cast iron nose cone. However, it’s still HUGE, even heavier, and an antique, even for a 30-year-old engine.
There is also a MT-family starter with a smaller aluminum nose cone that has the staggered 168T mounting hole pattern. This was used on manual transmission equipped F-bodies until MY1990 and trucks until about 1988. A relevant part number is AC Delco 3361157A (shown below). Logic suggests that this version of the 10MT starter will fit in the typical starter pocket on manual transmission bellhousings. However, I did not ever attempt to bolt one of these up to the bellhousing I selected, so I cannot positively confirm this.
Here’s a helpful site if you want to learn more about the various iterations of 10MT starters. It’s not comprehensive, but it will certainly get you started: http://rmcavoy.freeshell.org/starters.html
The more modern permanent magnet gear reduction (PMGR) starters used from the mid-90s forward usually (perhaps "always") fit the manual transmission bell housing. They’re also much (MUCH) smaller, lighter, and plenty powerful for an engine with up to 10:1 compression. There are variants for 153T and 168T flywheels. Once I knew the starter that I had was incompatible with the bellhousing I intended to run, this was the easy/obvious call.
I ended up buying a new (not rebuilt) TYC (brand) starter (p/n 106449L) from Rock Auto. Quality seems good; price was great. While TYC isn’t a brand most of us know anything about, if your daily driver is less than about 20 years old, chances are TYC is an OE supplier for something on your car (lamp assembly, side mirror assembly, window regulator mechanisms, fuel pump/sender assemblies, and yes, starters and alternators).
Plenty of folks swear by PowerMaster, Tuff Stuff and other 'performance aftermarket' alternators and starters. I don’t have a single bad thing to say about those products. I’ve used them in other applications with great success. For this budget-friendlier build, again I went with an OE replacement part. If it bites me in the backside, I’ll certainly let the readers here know.
The last detail in this flywheel/starter saga is starter bolts. What could be easier? Gen 1 and Gen 2 blocks use 3/8”-16 bolts, right? Right.
...of course, those bolts do have that knurled sections just after the threads that ensure a light interference fit to both the engine block and the ID of the starter mounting holes…
...and PMGR starters are (for the most part) designed around metric bolts with a 10mm shank, which also have a knurled sections, but with larger diameters than the SAE bolt variant...
All of this raises questions about how GM reliably mounted a PMGR starter that was designed around metric fasteners to an engine block that was designed around SAE (U.S. customary) units.
The answer is magical bolts…errr…at least hybrid bolts. (And no, hybrid bolts don’t have batteries that begin to fail after a few years of ownership.)
GM designed a small assortment of SAE/metric hybrid bolts that 3/8-16 threads with a knurled 10mm shank and a metric hex head. These bolts are designed to thread into 'legacy' engine blocks and allow for the newer (now at least 30-years old) PMGR starters to be reliable bolted in place without twisting or shifting.
I used GM p/n 12338064 which are SAE/metric hybrid bolts with 3/8-16 threads, the knurled 10mm shank, and 110mm (4.33”) under-head length. In the picture below you cane see how the step in the knurled section engages the engine block. Sorry that the picture is blurry.
The only minor annoyance I experienced once I had the starter and bolt details sorted out was that I did have to shim (visible in starter comparison picture) the starter away from the block using the readily available shim set to get proper pinion to ring clearance. I’m not sure if I could have avoided this with a different starter configuration, or if this is just par for the course.
If your starter hangs up, or you’re burning up starters regularly, check both the pinion clearance and the bolt configuration. The links above (and many other resources) describe the proper clearance for flywheel ring to starter pinion gears. Even if the clearance is set properly to begin with, if SAE bolts are used in a starter that is designed for a 10mm shank, the starter can shift/twist enough through use to cause an alignment problem after installation.
I know this post was way-down in the weeds, but hopefully it answers a couple of questions for someone. I'll dive into transmission selection and installation in the next post or two.
If that sounds less interesting than watching paint dry, I won’t be offended if you back out of this posting or close your browser.
The LT1 I’m working with is from a 1995 Corvette. It would seem to be reasonable to start with a flywheel from a 1995 Corvette for whatever manual transmission I’m going to work with. However, that would be a mistake.
The 1995 Corvette came with a ZF 6-speed (ZF-6) which has a clutch setup different than…well, any other GM vehicle.
From corvetteforum.com which is purportedly quoting (or at least relaying) information from a June 2000 issue of Car Craft magazine:
"Used exclusively in 89-96 Corvettes, the ZF six-speed is a massive, durable, and expensive transmission. Rebuild parts are hard to come by. (Vette warranties required trading in a bad trans to GM for a re-manufactured unit.) The ZF shares no common dimensions with traditional GM manual transmissions. Its nonstandard bellhousing accepts a Vette-only pull-style hydraulic clutch. Versions used behind the LT1/LT4 and DOHC LT5 engines have different length input shafts. GM uses a dual-mass flywheel to reduce noise from this massive, truck-like trans."
The up-shot of these details is that the ZF-6/Vette flywheel (dual-mass or otherwise) is also somewhere around 0.150” thinner than a conventional GM flywheel.
Another reasonable approach would seem to be using an F-Body flywheel. However, the 4th Gen F-bodies use a reverse clutch disc (where the compensator springs are closer to the crankshaft, rather than the conventional setup where the are closer to the transmission) so that the pressure plate and bellhousing can be slightly shorter (fore/aft). The narrow pressure plate assembly and shorter bellhousing necessitated the use of a (hydraulically actuated) fork and throwout bearing, and again, make total stack-up more mysterious than it needs to be for my build.
I definitely was not going to try to use a C4 ZF-6 or an 4th Gen F-body T56 transmission, so while the above information was interesting to me, the major revelation was: Don't use flywheels meant for those applications.
Another consideration was the use of the 153T flywheel versus the 168T flywheel. In a smaller/lighter car (Corvette, modern-ish F-Body), the smaller, lighter, lower inertia flywheel makes sense. Likewise, if you've built a high-revving, high powered engine, low-inertia flywheels make sense.
On a modestly-powered V8, with a 'normal' (5500rpm) redline, in a full-size pick-up (albeit a light version of a full-size pick-up), having a bit more inertia (heavier and/or larger diameter) flywheel isn’t an awful idea.
In fact, in one of my exchanges with the fine folks at Ram Clutch, they said that for a street-driven vehicle (classic muscle car, full-size cruiser, certainly a truck), the 168T flywheel is the better bet. Opinions will differ, but I found the input from a flywheel and clutch manufacturer helpful and reassuring.
This took me down the path of looking at truck flywheels for 1-piece rear main seal (1986 and newer) engines. Ultimately, I chose a cast iron, stock replacement style 168T flywheel. These use standard GM stack-up dimensions for clutch, pressure plate assemblies, and bellhousings.
The exact flywheel I bought weighed about 29-pounds, but the mass is decidedly located around the perimeter near the ring gear. (I find it interesting that the inertia of the flywheel under standard test conditions is usually hard to find.)
With the flywheel sorted out, I turned my attention to the starter.
As noted previously, the guy I bought the engine from kept the original Vette starter and gave me a MT-style starter with the engine.
The good news, I suppose, is that the MT-style has the staggered mounting holes indicating that it’s meant for a 168T flywheel. Also good news: I confirmed that it works.
However, I was unconvinced that using this monstrous starter was necessary, or even well-informed. While there is plenty of space in the engine bay of a full-size GM truck, the 10MT starter could only make exhaust routing (as an example) more difficult in the future.
Somewhat later in the assembly process I came to find out that the 10MT starter that I had would not work with the manual transmission bellhousing I selected. This is because the starter has a large cast aluminum “drive-end frame” (let’s just call it the nose cone) that supports the pinion shaft. This starter is usually only compatible with the starter pocket on automatic transmission cases. So, unless I wanted to grind off part of the nose cone of the starter, or hog out some of my brand new bellhousing with a die grinder, I had to get a different starter anyway.
There is an MT-style direct drive starter that was used on manual transmission starters into the early 1980s that I believe would work. For example, AC Delco 3361870 (shown below). This starter features a smaller cast iron nose cone. However, it’s still HUGE, even heavier, and an antique, even for a 30-year-old engine.
You must be registered for see images attach
There is also a MT-family starter with a smaller aluminum nose cone that has the staggered 168T mounting hole pattern. This was used on manual transmission equipped F-bodies until MY1990 and trucks until about 1988. A relevant part number is AC Delco 3361157A (shown below). Logic suggests that this version of the 10MT starter will fit in the typical starter pocket on manual transmission bellhousings. However, I did not ever attempt to bolt one of these up to the bellhousing I selected, so I cannot positively confirm this.
You must be registered for see images attach
Here’s a helpful site if you want to learn more about the various iterations of 10MT starters. It’s not comprehensive, but it will certainly get you started: http://rmcavoy.freeshell.org/starters.html
The more modern permanent magnet gear reduction (PMGR) starters used from the mid-90s forward usually (perhaps "always") fit the manual transmission bell housing. They’re also much (MUCH) smaller, lighter, and plenty powerful for an engine with up to 10:1 compression. There are variants for 153T and 168T flywheels. Once I knew the starter that I had was incompatible with the bellhousing I intended to run, this was the easy/obvious call.
I ended up buying a new (not rebuilt) TYC (brand) starter (p/n 106449L) from Rock Auto. Quality seems good; price was great. While TYC isn’t a brand most of us know anything about, if your daily driver is less than about 20 years old, chances are TYC is an OE supplier for something on your car (lamp assembly, side mirror assembly, window regulator mechanisms, fuel pump/sender assemblies, and yes, starters and alternators).
Plenty of folks swear by PowerMaster, Tuff Stuff and other 'performance aftermarket' alternators and starters. I don’t have a single bad thing to say about those products. I’ve used them in other applications with great success. For this budget-friendlier build, again I went with an OE replacement part. If it bites me in the backside, I’ll certainly let the readers here know.
You must be registered for see images attach
The last detail in this flywheel/starter saga is starter bolts. What could be easier? Gen 1 and Gen 2 blocks use 3/8”-16 bolts, right? Right.
...of course, those bolts do have that knurled sections just after the threads that ensure a light interference fit to both the engine block and the ID of the starter mounting holes…
...and PMGR starters are (for the most part) designed around metric bolts with a 10mm shank, which also have a knurled sections, but with larger diameters than the SAE bolt variant...
All of this raises questions about how GM reliably mounted a PMGR starter that was designed around metric fasteners to an engine block that was designed around SAE (U.S. customary) units.
The answer is magical bolts…errr…at least hybrid bolts. (And no, hybrid bolts don’t have batteries that begin to fail after a few years of ownership.)
GM designed a small assortment of SAE/metric hybrid bolts that 3/8-16 threads with a knurled 10mm shank and a metric hex head. These bolts are designed to thread into 'legacy' engine blocks and allow for the newer (now at least 30-years old) PMGR starters to be reliable bolted in place without twisting or shifting.
I used GM p/n 12338064 which are SAE/metric hybrid bolts with 3/8-16 threads, the knurled 10mm shank, and 110mm (4.33”) under-head length. In the picture below you cane see how the step in the knurled section engages the engine block. Sorry that the picture is blurry.
You must be registered for see images attach
The only minor annoyance I experienced once I had the starter and bolt details sorted out was that I did have to shim (visible in starter comparison picture) the starter away from the block using the readily available shim set to get proper pinion to ring clearance. I’m not sure if I could have avoided this with a different starter configuration, or if this is just par for the course.
If your starter hangs up, or you’re burning up starters regularly, check both the pinion clearance and the bolt configuration. The links above (and many other resources) describe the proper clearance for flywheel ring to starter pinion gears. Even if the clearance is set properly to begin with, if SAE bolts are used in a starter that is designed for a 10mm shank, the starter can shift/twist enough through use to cause an alignment problem after installation.
I know this post was way-down in the weeds, but hopefully it answers a couple of questions for someone. I'll dive into transmission selection and installation in the next post or two.
someotherguy
Truly Awesome
I don't think you'll be unhappy with the choice of the OEM style mini starter. They're perfectly good at cranking over big blocks; they perform effortlessly in most applications you could find in a GMT400 (except diesels and there's no helping those folks.) The Chinesium factor comes into play, but these days you get what you get.
Richard
Richard
nineno
Newbie
With the oil pump (re-)primed, the flywheel and starter saga behind me, and reasonably confident that the engine wasn’t eating itself from the inside out, I installed new spark plugs and cranked the motor again. The comparatively tiny PMGR starter rolled the motor over very nicely.
The spark plug wires were also in pretty rough shape, so I got a Taylor wire & plug boot kit, and the right boot/connector kit for the Opti-Spark. Specifically:
- Taylor 35671 30-feet of blue Spiro-Pro 8mm wire
- Taylor 46081 (Qty 8) gray 90-degree silicone boots and terminals
- Taylor 46052 (Qty 9) straight (180-degree) distributor boots, (Qty 1) 90-degree coil boot, & appropriate terminals (described as an LS/LT/Vortec boot kit)
The plugs were replaced with Champions.
Assembling the plug end of the wires was straightforward. Installing the distributor boots was an absolute bear of an undertaking. Yikes.
I’ve got a few tips if anyone undertakes the same project with the Optispark boots...but Tip 1 might be to consider 7mm plug wire.
With the accessory drive and busted water pump off the front of the engine, I decided to flush out the engine block. I made two little adapters from a 3/8” thick piece of Lexan (Plexiglass) I had laying around. I traced new water pump gaskets to get the profile and mounting hole locations. I bolted the plates to the block and then "eyeballed" the location of the coolant ports and used an auto-punch to mark the approximately-correct location of the inlet and outlet ports. From there, I drilled and tapped the plastic to accept hose barb fittings.
I screwed the adapters to the engine block and plumbed both coolant inlets to a garden hose fitting. The three outlets (2 directly from the block and one from the vapor port) drained to a bucket.
From there I ran the hottest water my water heater could make through the engine many times. All totaled, I probably ran a total of 60 to 75 gallons of hot water through the engine across 5 or 6 different occasions over a week period.
The first several rinses were gross, but most of the coloration was the red GM (Dexcool) coolant. I specifically ran the water that came out of the engine through an industrial filtration bag (10-micron polyester felt, if anyone cares). There were dried flakes of Dexcool and some fine rust, but nothing that I found particularly frightening. Best of all, water didn’t come pouring out of the exhaust ports or intake manifold! (I kid…sort-of.)
Once the water was running clean and I felt I had done all that I could with my homebrew flushing system, I used my shop vac to suck out as much water as I could. Feeling adventurous, I then decided to blow air through the cooling water jacket, from the outlet side of my shop vac. In case you were wondering, yes, this did cause a bit of a mess. But, I kept at it until no more water mist came out of the block, and the cooling ports were dry. Later the same day, I repeated the process to see if any water had pooled that could be blown out. No moisture came out.
With that task complete, I reinstalled the water pump and turned my attention to the transmission.
To make a very long story very short: I bought a T56 Magnum from American Powertrain. Most of the manual transmission vehicles that I have owned have been 6-speeds (`04 GTO, `08 Volvo S40 T5, `12 Buick Regal GS), and I’ve enjoyed them. Rather than over-think my selection or wait for some “great deal” to land in my lap, I went for a very highly regarded aftermarket-specific version of a very popular family of transmissions. I purchased the close ratio transmission. I'll share some gearing details a bit later on.
As a few other posters have noted elsewhere in this forum, American Powertrain knows their stuff, they’re helpful, and their package prices are good. If you’re willing to source a few parts on your own, you can save a few more dollars.
Here is what I omitted from the AP package and bought separately to save a few bucks. There are trade-offs, which I'll get into.
I probably could have saved a few more dollars, some time, and a little bit of fiddling around by running an OE-style (spring pre-load) hydraulic actuator (aka “slave cylinder”). I only learned this while measuring and shimming the Ram hydraulic actuator/bearing setup. For anyone that is considering a Magnum transmission, I would recommend looking into the OE-style actuation cylinder like GM 24264183.
I'll dive into some of the minutia leading up to the installation of the engine to the transmission and additional lessons learned, next.
The spark plug wires were also in pretty rough shape, so I got a Taylor wire & plug boot kit, and the right boot/connector kit for the Opti-Spark. Specifically:
- Taylor 35671 30-feet of blue Spiro-Pro 8mm wire
- Taylor 46081 (Qty 8) gray 90-degree silicone boots and terminals
- Taylor 46052 (Qty 9) straight (180-degree) distributor boots, (Qty 1) 90-degree coil boot, & appropriate terminals (described as an LS/LT/Vortec boot kit)
The plugs were replaced with Champions.
Assembling the plug end of the wires was straightforward. Installing the distributor boots was an absolute bear of an undertaking. Yikes.
I’ve got a few tips if anyone undertakes the same project with the Optispark boots...but Tip 1 might be to consider 7mm plug wire.
You must be registered for see images attach
With the accessory drive and busted water pump off the front of the engine, I decided to flush out the engine block. I made two little adapters from a 3/8” thick piece of Lexan (Plexiglass) I had laying around. I traced new water pump gaskets to get the profile and mounting hole locations. I bolted the plates to the block and then "eyeballed" the location of the coolant ports and used an auto-punch to mark the approximately-correct location of the inlet and outlet ports. From there, I drilled and tapped the plastic to accept hose barb fittings.
You must be registered for see images attach
I screwed the adapters to the engine block and plumbed both coolant inlets to a garden hose fitting. The three outlets (2 directly from the block and one from the vapor port) drained to a bucket.
You must be registered for see images attach
From there I ran the hottest water my water heater could make through the engine many times. All totaled, I probably ran a total of 60 to 75 gallons of hot water through the engine across 5 or 6 different occasions over a week period.
The first several rinses were gross, but most of the coloration was the red GM (Dexcool) coolant. I specifically ran the water that came out of the engine through an industrial filtration bag (10-micron polyester felt, if anyone cares). There were dried flakes of Dexcool and some fine rust, but nothing that I found particularly frightening. Best of all, water didn’t come pouring out of the exhaust ports or intake manifold! (I kid…sort-of.)
You must be registered for see images attach
Once the water was running clean and I felt I had done all that I could with my homebrew flushing system, I used my shop vac to suck out as much water as I could. Feeling adventurous, I then decided to blow air through the cooling water jacket, from the outlet side of my shop vac. In case you were wondering, yes, this did cause a bit of a mess. But, I kept at it until no more water mist came out of the block, and the cooling ports were dry. Later the same day, I repeated the process to see if any water had pooled that could be blown out. No moisture came out.
With that task complete, I reinstalled the water pump and turned my attention to the transmission.
To make a very long story very short: I bought a T56 Magnum from American Powertrain. Most of the manual transmission vehicles that I have owned have been 6-speeds (`04 GTO, `08 Volvo S40 T5, `12 Buick Regal GS), and I’ve enjoyed them. Rather than over-think my selection or wait for some “great deal” to land in my lap, I went for a very highly regarded aftermarket-specific version of a very popular family of transmissions. I purchased the close ratio transmission. I'll share some gearing details a bit later on.
As a few other posters have noted elsewhere in this forum, American Powertrain knows their stuff, they’re helpful, and their package prices are good. If you’re willing to source a few parts on your own, you can save a few more dollars.
Here is what I omitted from the AP package and bought separately to save a few bucks. There are trade-offs, which I'll get into.
- Flywheel - Platinum Driveline FW525 (previously discussed)
- Flywheel bolts - ARP 200-2807
- Clutch/Pressure Plate kit – Ram Clutch 92764
- Pressure plate bolts - Ram Clutch 490
- Hydraulic Actuator – Ram Clutch 78160
- Bellhousing – Lakewood/Holley LK4100K1
- OE replacement clutch master cylinder – Luk LMC134
You must be registered for see images attach
I probably could have saved a few more dollars, some time, and a little bit of fiddling around by running an OE-style (spring pre-load) hydraulic actuator (aka “slave cylinder”). I only learned this while measuring and shimming the Ram hydraulic actuator/bearing setup. For anyone that is considering a Magnum transmission, I would recommend looking into the OE-style actuation cylinder like GM 24264183.
I'll dive into some of the minutia leading up to the installation of the engine to the transmission and additional lessons learned, next.
Looking good but did you leave enough length in your right side plug wires to clear the #2 exhaust port. In the pic it looks like the wires are going right across the port where your manifold or header tube is going to be.
nineno
Newbie
I didn’t find any great resources for total stack-up from engine block to transmission face for Chevy small blocks which is what prevented me from going with the OE-style (spring pre-load) clutch actuator (slave cylinder) I noted above. Does anyone have this information? I can’t imagine I’m the only hobbyist that has wanted it…
I opted for the Holley/Lakewood cast aluminum bell housing because of the modest power levels. It looks like a pretty nice piece, but a couple of attributes left me rather unimpressed.
First, the bell housing fits to the engine very nicely, but it wasn’t until I had the flywheel installed that I figured out that the stamped steel inspection cover was designed for a 2-piece rear main seal (pre-1986) engine. I sent a note to Holley customer support, and they confirmed, as follows:
"It looks like it was designed around a 2-Piece Rear Main Seal. We do not offer a Shield for the One Piece."
Thanks, Holley.
It would be nice if they merely explained this in the product description. 'Dust cover is designed for (1985 and older) 2-piece rear main seal engines and will require modification to fit (1986 and newer) 1-piece rear main seal engines.'
If they felt particularly generous, they could even provide a small paper pattern of what needs to be cut away for use with a 1pc RMS engine. But, no. Not Holley. They just left it a mystery.
Rather than try to undo the flywheel bolts I had just Loc-Tited into the crankshaft several days earlier, I made a paper doll model of the inspection cover and measured as best I could with a machinist scale and a flashlight between the flywheel and engine block to determine how much needed to be removed from the inspection cover. Then I cut away my paper doll model with scissors until it fit. From there, I measured and laid out what I needed to remove from stamped steel inspection cover.
In the end, about 3/16" was trimmed from the arc that passes around the rear main seal carrier, as well as 2 notches that started out as 9/16” holes on either side of the RMS cut-out. The cutout clears the fasteners that hold the RMS carrier casting in place.
With that sorted out, the bell housing and inspection cover fit to the engine.
The next order of business was to measure the run-out of the flywheel relative to the bell housing. I took measurements every 15-degrees and set up a spreadsheet to determine if I needed to adjust the bell housing with offset dowel pins, and if so, what offset and direction I needed.
It was during this process that I first realized the Lakewood bell housing was missing 1 transmission-side mounting hole. Furthermore, it maintained a mounting hole from the original (non-Magnum) T56 used on the Viper, etc.
Here you can see the location of the missing mounting hole and the "legacy" mounting hole.
Here is a side-by-side comparison of a pre-Magnum (Viper, specifically) T-56 and a current T-56 Magnum transmission.
Now, I understand that Holley/Lakewood is trying to make their parts fit as many applications as possible, but it doesn’t appear that there is any reason not to include the Magnum mounting hole just before the 9 o’clock position. This would not preclude the bell housing from working with the pre-Magnum transmission case, as far as I can tell. It appears that independent bell housing manufacturer Quick Draw (of Ohio) makes a bell housing that has all of the mounting locations for the pre-Magnum and Magnum generation of Tremec 6-speeds. Furthermore, another Holley brand (Quicktime) makes an SFI rated steel bell housing that has all the bolt holes for both generations of Tremec 6-speed. Com’on Holley. Can’t you find a way to take the best attributes from all of the designs you now own and incorporate them more broadly?
The omission of a transmission mounting bolt had me very nervous, so I reached out to both Ram Clutch and American Powertrain and both confirmed that this same bolt hole is omitted on several (but not all) aftermarket bellhousings and does not appear to cause a problem. So, I proceeded with the bell housing I already had. (To be clear, I do not love this… If I roach my brand new transmission in 5,000 miles, I’m gunna be pissed…)
If you’re considering a a T56 Magnum to Gen 1/Gen 2 small block, I’d strongly recommend evaluating MANY bell housing options before you buy. I had hoped to use an OE bell housing, but I couldn’t positively identify which, if any, GM parts would connect a pre-LS engine to a T56 Magnum, with the right housing depth to package a conventional flywheel/clutch/pressure plate assembly. (The F-body bell housings use a compact “reversed” clutch setup which requires a special flywheel, etc.)
If anyone has any knowledge and good recommendations on this topic, please feel free to share them.
After all of this screwing around, I eventually got around to measuring the run-out of the bell housing. I used a cheap magnetic base and digital indicator from Harbor Freight. The short story is that I needed to pound out the factory installed dowel pins and replace them with 0.007” offset pins that moved the bell housing down and to the left. The offset of both pins was clocked to approximately 7 o’clock. Once installed, the total indicated run-out was less than 0.003”. Jackpot!
The transmission I chose is the close ratio variant of the T56 Magnum (p/n TUET11009), which has a 2.60 first gear and an 0.63 6th gear. Second through 6th are quite evenly spaced (unlike the OE transmissions in F-bodies and mid-aughts GTOs). The tire sizes I’m considering all have a circumference near 90”, which means an axle ratio of about 4.10:1 should be appropriate.
The gears in the truck currently are mileage-maker 3.08:1, so I’ll have to do something about that, eventually. In the sheet above, the chart shows 4.11 gears.
Some clutch details coming up in the next installment.
I opted for the Holley/Lakewood cast aluminum bell housing because of the modest power levels. It looks like a pretty nice piece, but a couple of attributes left me rather unimpressed.
First, the bell housing fits to the engine very nicely, but it wasn’t until I had the flywheel installed that I figured out that the stamped steel inspection cover was designed for a 2-piece rear main seal (pre-1986) engine. I sent a note to Holley customer support, and they confirmed, as follows:
"It looks like it was designed around a 2-Piece Rear Main Seal. We do not offer a Shield for the One Piece."
Thanks, Holley.
It would be nice if they merely explained this in the product description. 'Dust cover is designed for (1985 and older) 2-piece rear main seal engines and will require modification to fit (1986 and newer) 1-piece rear main seal engines.'
If they felt particularly generous, they could even provide a small paper pattern of what needs to be cut away for use with a 1pc RMS engine. But, no. Not Holley. They just left it a mystery.
Rather than try to undo the flywheel bolts I had just Loc-Tited into the crankshaft several days earlier, I made a paper doll model of the inspection cover and measured as best I could with a machinist scale and a flashlight between the flywheel and engine block to determine how much needed to be removed from the inspection cover. Then I cut away my paper doll model with scissors until it fit. From there, I measured and laid out what I needed to remove from stamped steel inspection cover.
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In the end, about 3/16" was trimmed from the arc that passes around the rear main seal carrier, as well as 2 notches that started out as 9/16” holes on either side of the RMS cut-out. The cutout clears the fasteners that hold the RMS carrier casting in place.
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With that sorted out, the bell housing and inspection cover fit to the engine.
The next order of business was to measure the run-out of the flywheel relative to the bell housing. I took measurements every 15-degrees and set up a spreadsheet to determine if I needed to adjust the bell housing with offset dowel pins, and if so, what offset and direction I needed.
It was during this process that I first realized the Lakewood bell housing was missing 1 transmission-side mounting hole. Furthermore, it maintained a mounting hole from the original (non-Magnum) T56 used on the Viper, etc.
Here you can see the location of the missing mounting hole and the "legacy" mounting hole.
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Here is a side-by-side comparison of a pre-Magnum (Viper, specifically) T-56 and a current T-56 Magnum transmission.
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Now, I understand that Holley/Lakewood is trying to make their parts fit as many applications as possible, but it doesn’t appear that there is any reason not to include the Magnum mounting hole just before the 9 o’clock position. This would not preclude the bell housing from working with the pre-Magnum transmission case, as far as I can tell. It appears that independent bell housing manufacturer Quick Draw (of Ohio) makes a bell housing that has all of the mounting locations for the pre-Magnum and Magnum generation of Tremec 6-speeds. Furthermore, another Holley brand (Quicktime) makes an SFI rated steel bell housing that has all the bolt holes for both generations of Tremec 6-speed. Com’on Holley. Can’t you find a way to take the best attributes from all of the designs you now own and incorporate them more broadly?
The omission of a transmission mounting bolt had me very nervous, so I reached out to both Ram Clutch and American Powertrain and both confirmed that this same bolt hole is omitted on several (but not all) aftermarket bellhousings and does not appear to cause a problem. So, I proceeded with the bell housing I already had. (To be clear, I do not love this… If I roach my brand new transmission in 5,000 miles, I’m gunna be pissed…)
If you’re considering a a T56 Magnum to Gen 1/Gen 2 small block, I’d strongly recommend evaluating MANY bell housing options before you buy. I had hoped to use an OE bell housing, but I couldn’t positively identify which, if any, GM parts would connect a pre-LS engine to a T56 Magnum, with the right housing depth to package a conventional flywheel/clutch/pressure plate assembly. (The F-body bell housings use a compact “reversed” clutch setup which requires a special flywheel, etc.)
If anyone has any knowledge and good recommendations on this topic, please feel free to share them.
After all of this screwing around, I eventually got around to measuring the run-out of the bell housing. I used a cheap magnetic base and digital indicator from Harbor Freight. The short story is that I needed to pound out the factory installed dowel pins and replace them with 0.007” offset pins that moved the bell housing down and to the left. The offset of both pins was clocked to approximately 7 o’clock. Once installed, the total indicated run-out was less than 0.003”. Jackpot!
The transmission I chose is the close ratio variant of the T56 Magnum (p/n TUET11009), which has a 2.60 first gear and an 0.63 6th gear. Second through 6th are quite evenly spaced (unlike the OE transmissions in F-bodies and mid-aughts GTOs). The tire sizes I’m considering all have a circumference near 90”, which means an axle ratio of about 4.10:1 should be appropriate.
You must be registered for see images attach
The gears in the truck currently are mileage-maker 3.08:1, so I’ll have to do something about that, eventually. In the sheet above, the chart shows 4.11 gears.
Some clutch details coming up in the next installment.
Last edited:
nineno
Newbie
I've been meaning to drop a reply to a few comments/questions for awhile. Before I forget (or procrastinate) again...
If the starter craps out on me, I'll transition to something a bit more "boutique" and/or "domestic."
Below are two pics with the OE (Corvette) manifold held loosely in place.
Looking down...
Low angle, looking forward...
Also, a quick update: I re-installed the fuel rail and a set of rebuilt and flow-matched Bosch III injectors from CS Performance Fuel Injection. Price was excellent. It took a couple of tries to get a hold of someone for some tech support, but once I reached them, everything went smoothly.
The flow rate is the same as the OE injectors, but with (supposedly) better atomization. They are slightly higher impedance (eg: lower current draw), so that can only help the PCM.
At the end of the day, the injectors that were on the engine had stale fuel sitting in them for several years. While they worked enough for the engine to start, idle, and rev, I can't imagine they were working well. The cost to have them re-built was about the same as buying the Bosch IIIs. (Now, I have one full set of Vette injectors and one full set of F-body injectors that came with the engine, as well. Maybe I can sell these off to a rebuilder or someone doing a resto...)
Dang, the saturation on that picture makes the intake manifold look way worse than it looks in person! Yuck...
I have a couple of random questions for the folks following this thread:
Question 1
Has anyone come across pictures of OE Gen 2 (LT1/LT4) Vette manifolds used in a c1500? I suppose this would be about the same as using Rams Horn-style exhaust manifolds in a c1500. Is that do-able?
There was some conversation about it in these two threads (https://www.gmt400.com/threads/ram-horn-applications.65522/ & https://www.gmt400.com/threads/ram-horn.43188/). It seems like the general consensus is "No, they won't fit."
If I can't make the OE Vette manifolds fit (cleanly), I may look into the Hooker cast manifolds shown in the first linked thread. (They may not work with LT1 heads, though!)
I'll test-fit the powertrain sometime soon so that I can punch a hole in the floor for the shift lever. Worst case scenario, I'll check the manifold fitment at that point.
Question 2
Any handy links to good overviews of exhaust routing on a C1500 from the bottom-up, or with the bed off? There are lots of shots showing sections of exhaust, but I'd like a bit more of an overview of what folks have done.
As always, thanks for the feedback and for following along!
Thanks, Sean! Different is absolutely one of the objectives. (Cost-consciousness and drive-able are, too.)
The confirmation on the choice of mini-starter is much appreciated, Richard.
If the starter craps out on me, I'll transition to something a bit more "boutique" and/or "domestic."
Fair question based on the picture I shared, ScooterWrench! That pic is sort-of an optical illusion, though. The plug wires are following the same path (using the same wire retainers) as in the original application.
Below are two pics with the OE (Corvette) manifold held loosely in place.
Looking down...
You must be registered for see images attach
Low angle, looking forward...
You must be registered for see images attach
Also, a quick update: I re-installed the fuel rail and a set of rebuilt and flow-matched Bosch III injectors from CS Performance Fuel Injection. Price was excellent. It took a couple of tries to get a hold of someone for some tech support, but once I reached them, everything went smoothly.
The flow rate is the same as the OE injectors, but with (supposedly) better atomization. They are slightly higher impedance (eg: lower current draw), so that can only help the PCM.
At the end of the day, the injectors that were on the engine had stale fuel sitting in them for several years. While they worked enough for the engine to start, idle, and rev, I can't imagine they were working well. The cost to have them re-built was about the same as buying the Bosch IIIs. (Now, I have one full set of Vette injectors and one full set of F-body injectors that came with the engine, as well. Maybe I can sell these off to a rebuilder or someone doing a resto...)
You must be registered for see images attach
Dang, the saturation on that picture makes the intake manifold look way worse than it looks in person! Yuck...
I have a couple of random questions for the folks following this thread:
Question 1
Has anyone come across pictures of OE Gen 2 (LT1/LT4) Vette manifolds used in a c1500? I suppose this would be about the same as using Rams Horn-style exhaust manifolds in a c1500. Is that do-able?
There was some conversation about it in these two threads (https://www.gmt400.com/threads/ram-horn-applications.65522/ & https://www.gmt400.com/threads/ram-horn.43188/). It seems like the general consensus is "No, they won't fit."
If I can't make the OE Vette manifolds fit (cleanly), I may look into the Hooker cast manifolds shown in the first linked thread. (They may not work with LT1 heads, though!)
I'll test-fit the powertrain sometime soon so that I can punch a hole in the floor for the shift lever. Worst case scenario, I'll check the manifold fitment at that point.
Question 2
Any handy links to good overviews of exhaust routing on a C1500 from the bottom-up, or with the bed off? There are lots of shots showing sections of exhaust, but I'd like a bit more of an overview of what folks have done.
As always, thanks for the feedback and for following along!
Yeah,you've got plenty of plug wire/exhaust clearance,looks good.
I don't think center dump manifolds will work on a T-400. You may be able to bolt the manifolds on but I don't think you would be able to get the exhaust up on them. Why do you want to run iron logs?
I'll be building my exhaust in the near future,I'll take pics!
nineno
Newbie
That's the impression I was gathering. I'll probably have a closer look with the powertrain resting in the truck, but I'll also start considering some other options.
The short answer is "because I already have them, and the Vette LT1 manifolds actually flow reasonably well."
(I also have a set of F-Body LT1 manifolds...they do not flow well, though they may actually fit in the truck just fine.)
Awesome. Thanks!
Check out L31Max's budget build. He just proved that headers will out perform even good aftermarket iron logs.
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