My 454 Rebuild

[Spareparts]

Oh, man. Sounds like short-compression-height "rebuilder" pistons. Even with full compression height, they tend to be .020--.025 below deck; which is not a good thing. The earliest of these engines--the way they were designed--they had .020-ish embossed-steel-shim head gaskets. .025 below deck, plus .020 head gasket = .045 quench/squish distance, about as big as you'd really want.

Add the typical .040 head gasket to .035 below deck piston tops, and you're deep into detonation territory at .075. Between about .050 and .100 or so of squish/quench distance, detonation is common due to the restriction of flame-front, and an excess of end-gasses that get heated and then spontaniously combust. Below .050, there's enough squish/quench to speed combustion, and a reduction of end-gasses 'cause they've largely been squeezed-out; what little there is, is cooled by proximity to the head surface. Above .100, the chamber becomes "open", there's heaps of fuel-air a long way from the spark plug, but the flame front can get to them before they detonate. The "open" chamber has a somewhat lazy burn, requires additional spark advance, but at least it doesn't have the terrible detonation characteristics.

Yeah, i was looking at that also but i wanted to wait till i could check piston to valve clearance. I'm sure i have way more than enough but i want to check to be sure.
Thinnest head gasket i can find is an all copper .021 compressed head gasket. Worth it or not im not sure.
The more im finding out and the more im learning, the more im leaning to just putting it together the way it is.
For sure not what i wanted, but better than no engine at all.

 

[BeXtreme]

Here is a shot of the pistons for ya. At TDC they sit .035 below deck. I checked 3 and they all were the same.

I hadn't seen this post before. That is super weird. Those are engine tech pistons, but they are supposedly the correct ones for the Gen VI. I have Sealed Power H749CP pistons and they went .020" over on my rebuild. My measured deck clearance was .010" on mine. They did not mill my motor, just surfaced the deck about .005". The spec sheet on my pistons gives a compression height of 1.625" and the engine tech data says yours should have 1.627", so you should actually have had LESS deck clearance than my setup, not more. The dumb thing is that the Engine tech piston set costs at least $25-50 MORE at every online retailer I could find, and none of the big names like summit or Jegs carry it. The only place that came up with them for sale was ebay and amazon.

 

[BeXtreme]

Wish i could have got Com Cams on the phone today. I just discovered these. Looks like all three will work just need to figure out what one would work best for me.

Tri-Power Xtreme 210/218 Hydraulic Roller Cam for Chevrolet Big Block GEN VI

HYDRAULIC ROLLER-Optimized horsepower with good torque & average fuel economy.

www.compcams.com

Tri-Power Xtreme 202/212 Hydraulic Roller Cam for Chevrolet Big Block GEN VI

HYDRAULIC ROLLER-Exceptional torque with good horsepower & moderate fuel economy.

www.compcams.com

Tri-Power Xtreme 194/206 Hydraulic Roller Cam for Chevrolet Big Block GEN VI

HYDRAULIC ROLLER-Optimized fuel mileage with good torque horsepower.

www.compcams.com

If you are thinking about any of these, you might as well just get the stock one reground. Next best thing would be the 454 HO cam. Last choice would be one of these. It will cost you more and have less power with any of these three than the previous two options.

 

[Spareparts]

Talked to Comp cams just now. Not really helpful i think. The dude just asked What year, what's it in, what engine, stock or modified.
Told him stock more or less a stock rebuild keeping the stock FI, bored .030 over and i plan on getting a tune. He recommended 1 cam. 01-410-8 and there was no other cam he could suggest.

 

[Supercharged111]

Talked to Comp cams just now. Not really helpful i think. The dude just asked What year, what's it in, what engine, stock or modified.
Told him stock more or less a stock rebuild keeping the stock FI, bored .030 over and i plan on getting a tune. He recommended 1 cam. 01-410-8 and there was no other cam he could suggest.

STOP TALKING TO COMP! ! ! Dude doesn't know$h!t* about fvkc just a nutless monkey reading off of a computer screen.

 

[Spareparts]

I hadn't seen this post before. That is super weird. Those are engine tech pistons, but they are supposedly the correct ones for the Gen VI. I have Sealed Power H749CP pistons and they went .020" over on my rebuild. My measured deck clearance was .010" on mine. They did not mill my motor, just surfaced the deck about .005". The spec sheet on my pistons gives a compression height of 1.625" and the engine tech data says yours should have 1.627", so you should actually have had LESS deck clearance than my setup, not more. The dumb thing is that the Engine tech piston set costs at least $25-50 MORE at every online retailer I could find, and none of the big names like summit or Jegs carry it. The only place that came up with them for sale was ebay and amazon.

So here is the thing. Wanting to know more this morning i went and got a dial micrometer with a mag base. because i did not trust the feeler gauge method.
I found my piston to deck height varied by what i consider a lot!. I did make sure pistons were sitting .000 at 4 points at TDC so piston rock was not a factor.
1: .035
2: .025
3: .034
4: .027
5: .027
6: .022
7: .020
8: .020
I went reading about what is acceptable variance and it seems that a stock block can be all over the place and finding this is a normal situation. It seems most machine shops just do the bare minimum like .005 when they surface a block and do not check for things like core shift and the fiddly measurement stuff.
It also seems when engine manufactures like gm/ford mass produce engines there is only 1 thing they really have a tight tolerance on. The relation of crankshaft to bell housing surface is as close to 90deg as possible.
So sense i did not specify anything they did not check anything and just did the normal .005 surface job to make sure it's flat.
If i had said i wanted the pistons to sit say .010 below deck then im sure all would be.
After researching all this i still wonder if i have some tolerance stack up happening?. Are engine tech pistons junk? rod stretch?
Now that i think about it, i should have measured how much piston rock each piston has. If they vary a bunch i would call the pistons junk because the bore is 4.280 as i measured them all this morning also.
Then again maybe im way over thinking this and running off on rabbit trails.

 

[BeXtreme]

So here is the thing. Wanting to know more this morning i went and got a dial micrometer with a mag base. because i did not trust the feeler gauge method.
I found my piston to deck height varied by what i consider a lot!. I did make sure pistons were sitting .000 at 4 points at TDC so piston rock was not a factor.
1: .035
2: .025
3: .034
4: .027
5: .027
6: .022
7: .020
8: .020
I went reading about what is acceptable variance and it seems that a stock block can be all over the place and finding this is a normal situation. It seems most machine shops just do the bare minimum like .005 when they surface a block and do not check for things like core shift and the fiddly measurement stuff.
It also seems when engine manufactures like gm/ford mass produce engines there is only 1 thing they really have a tight tolerance on. The relation of crankshaft to bell housing surface is as close to 90deg as possible.
So sense i did not specify anything they did not check anything and just did the normal .005 surface job to make sure it's flat.
If i had said i wanted the pistons to sit say .010 below deck then im sure all would be.
After researching all this i still wonder if i have some tolerance stack up happening?. Are engine tech pistons junk? rod stretch?
Now that i think about it, i should have measured how much piston rock each piston has. If they vary a bunch i would call the pistons junk because the bore is 4.280 as i measured them all this morning also.
Then again maybe im way over thinking this and running off on rabbit trails.

How are you measuring this? If you don't have a piston bridge and dial indicator, you are going to have suspect numbers. Basically you rotate the motor on the stand until the deck face is flat. Place the bridge and dial indicator across the deck surface so that both feet and the dial indicator are on machined deck surface. Zero out the gauge. Now you are ready to measure each piston deck clearance by putting the feet on either side of the piston on the deck surface and the dial indicator on the piston.

Some people like to measure both top and bottom of the piston while rocking it and use the average reading. I personally just took the measurement from the middle and moved on, mine is just a stock rebuild and I was doing verification only for my piece of mind.

Your numbers make me think your deck just isn't quite square, which is common. If this was a high performance max effort build, I would say to have the shop line hone it and square the block decks. Since you aren't, it isn't a big deal. The bigger concern for me is that the piston compression height given by engine tech seems to have either been wrong or very loose tolerance. It probably still isn't enough to matter for your application though. I would just run a chevrolet performance .022 compression height head gasket and send it.

 

[Spareparts]

It is far from a max effort rebuild. Was thinking a copper .021 head gasket but i sure like the price of the one you mentioned WAY better!
Thanks my friend!

 

[Schurkey]

As said--you need a deck-bridge. A mag-base and dial indicator doesn't have a repeatable "zero" between the deck and the piston. Piston rock is not a significant problem if you're measuring in-line with the piston pin.

Any automotive machine shop with reasonable equipment will deck the block square to the crankshaft saddles. In other words, the "machine" centers the block on the crank saddles, then the block is tipped 45 degrees either way, and the decks are milled. They end up "square" to the crank centerline, flat, smooth, and exactly 90 degrees apart. Thus the usual name for this process--"Square-decking" the block. The machine shop will generally take the minimum cut needed to clean-up the surfaces. The smart person tells the shop to "Zero-deck" or nearly-zero-deck the block; enough material is removed to get the piston tops level with the top of the block, so that the typical and inexpensive .040 gasket leaves a perfect quench distance.

If your deck clearance varies, it "shouldn't" be variations of deck height IF the machine shop centers the block on the main saddles. However, I had the engine block currently in my K1500 decked at a shop with prehistoric equipment. The block is crammed into the milling machine so that the existing deck is more-or-less horizontal, and then the machine cuts it. The set-up relies on the OEM machining which is almost always flawed to begin with, along with operator skill; and gets worse as the block is stress-relieved over two hundred thousand miles of heat- and vibration cycles. (i.e., the block warps in service.)

Next up is the center-to-center distance of the connecting rods. Aftermarket rods can be expected to have tight C-C tolerances; OEM rods not-so-much. And "resized" rods in most cases will have shorter C-C distance than stock because of the remachining done. A mix of "short" and "long" rods will cause the deck clearance to vary.

Another issue is the stroke of the crankshaft. OEM cranks rarely have "perfect" stroke length, and they're often not at perfect 90-degree intervals as they should be. So IF (big IF) the crank stroke is correct...it may be at the wrong angle in relation to the other crank throws. The 1--2, 3--4, 5--6, and 7--8 crank throws should be exactly 90 degrees away from each other. In practice, this could be 90--89--91--90 or some such. In this case, given a knowledgeable and CARING crank grinder operator, and equipment in reasonable condition, I'd trust a reground crank more than an OEM "standard" crank because minor problems with the original crank machining can be "ground out" during the undersizing process.

Lastly, there could be variations in piston compression height. Realistically, this is the last thing I'd check in your situation. Even pistons from India seem to be pretty uniform these days.

Since so many things affect piston-to-deck clearance; tolerance stack-up is a genuine issue. A guy can pisss-'n'-moan and spend hours selecting "short" rods to go with "tall" pistons, or long rods to fit the high parts of the deck. No, thanks.

My most-recent 5.7L has returned from my favorite machine shop having been square-decked. Instead of milling excess material from the decks to get to "zero deck", I had the standard/standard crank offset ground on the rod journals to gain .020 of throw (.040 of stroke, .020 "up" and .020 "down") Now the pistons go up far enough to be level with the block, instead of cutting the block to become level with the pistons. I gain almost four cubic inches in the process, and I get to claim my engine is a "stroker".

Copper head gaskets are not suitable for long-term use. Fine on a "race" engine, not suitable for street-driven, "ordinary" rebuilds. I just looked-up the .022 gasket
www.summitracing.com/parts/nal-12555728/make/chevrolet

CHEVROLET Chevrolet Performance 12555728 Chevrolet Performance Head Gaskets | Summit Racing

Free Shipping - Chevrolet Performance Head Gaskets with qualifying orders of $109. Shop Head Gaskets at Summit Racing.

www.summitracing.com

Looks like a winner. Not so thin as to cause a problem with your "tighter" cylinders, and about as good as you can hope for with your problem cylinders.

 

[BeXtreme]

Any automotive machine shop with reasonable equipment will deck the block square to the crankshaft saddles. In other words, the "machine" centers the block on the crank saddles, then the block is tipped 45 degrees either way, and the decks are milled. They end up "square" to the crank centerline, flat, smooth, and exactly 90 degrees apart. Thus the usual name for this process--"Square-decking" the block. The machine shop will generally take the minimum cut needed to clean-up the surfaces. The smart person tells the shop to "Zero-deck" or nearly-zero-deck the block; enough material is removed to get the piston tops level with the top of the block, so that the typical and inexpensive .040 gasket leaves a perfect quench distance.

If your deck clearance varies, it "shouldn't" be variations of deck height IF the machine shop centers the block on the main saddles. However, I had the engine block currently in my K1500 decked at a shop with prehistoric equipment. The block is crammed into the milling machine so that the existing deck is more-or-less horizontal, and then the machine cuts it. The set-up relies on the OEM machining which is almost always flawed to begin with, along with operator skill; and gets worse as the block is stress-relieved over two hundred thousand miles of heat- and vibration cycles. (i.e., the block warps in service.)

Next up is the center-to-center distance of the connecting rods. Aftermarket rods can be expected to have tight C-C tolerances; OEM rods not-so-much. And "resized" rods in most cases will have shorter C-C distance than stock because of the remachining done. A mix of "short" and "long" rods will cause the deck clearance to vary.

Another issue is the stroke of the crankshaft. OEM cranks rarely have "perfect" stroke length, and they're often not at perfect 90-degree intervals as they should be. So IF (big IF) the crank stroke is correct...it may be at the wrong angle in relation to the other crank throws. The 1--2, 3--4, 5--6, and 7--8 crank throws should be exactly 90 degrees away from each other. In practice, this could be 90--89--91--90 or some such. In this case, given a knowledgeable and CARING crank grinder operator, and equipment in reasonable condition, I'd trust a reground crank more than an OEM "standard" crank because minor problems with the original crank machining can be "ground out" during the undersizing process.

Lastly, there could be variations in piston compression height. Realistically, this is the last thing I'd check in your situation. Even pistons from India seem to be pretty uniform these days.

Since so many things affect piston-to-deck clearance; tolerance stack-up is a genuine issue. A guy can pisss-'n'-moan and spend hours selecting "short" rods to go with "tall" pistons, or long rods to fit the high parts of the deck. No, thanks.

My most-recent 5.7L has returned from my favorite machine shop having been square-decked. Instead of milling excess material from the decks to get to "zero deck", I had the standard/standard crank offset ground on the rod journals to gain .020 of throw (.040 of stroke, .020 "up" and .020 "down") Now the pistons go up far enough to be level with the block, instead of cutting the block to become level with the pistons. I gain a couple of cubic inches in the process, and I get to claim my engine is a "stroker".

Copper head gaskets are not suitable for long-term use. Fine on a "race" engine, not suitable for street-driven, "ordinary" rebuilds. I'm not familiar with this .022 head gasket--got a link? This isn't a steel-shim unit...right?

I hadn't even thought of the offset grind! I had my 350 decked .020" on the most recent rebuild.


The headgaskets I was talking about are chevrolet performance composite gaskets. They use the Permatorque material. I have the same style on my 350 and they work great.

https://www.summitracing.com/parts/nal-12555728/make/chevrolet