Intake swap thought

[Pinger]

Its not the dog house thats in the way. Its the metal body structure under the wiper cowl. Posted this picture earlier. That bonnet is really sandwiched in there. Dumb on GMs part not to have just put a LT1 in these vans. Could have used a B-car engine, low mounted compressor and all. Then again I do not know why all these trucks did not get a TPI or a LT1 except that GM likes to cheap out and fall behind. The spider was trouble when they first came out with it in the 92 4.3L CPI and GM was well aware by 94 much less 95 they had problems with them. My uncle lemon lawed his 92 S10 Blazer because of the spider when it was new.

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Can you fit additional feeder ducts to the side of the cowl? Like auxiliary exhaust ports on a 2-stroke cylinder, either side of the main exhaust port.

 

[tayto]

GM could have easily changed the rear-end gearing to get the TPI to where it needed to be to pull the truck down the road. Like I said it was a cost thing. GM kept the Q-Jet after other manufacturers had gone to EFI. Then they kept the TBI well after other manufacturers had port fuel injection. Then the spiders. Took until 1999 to get a proper EFI system on a GM truck with the new GMT800s and until 2003 for them to put a decent fuel system on the V8 vans (except for the 01-02 8.1Ls). GM had sequential port fuel injection and distributorless ignition in about 1985 on some of the V6 cars.

I think the LT1 got abandoned because of the GenIII myself. With the B/D cars getting phased out in 1996 and the Corvette going to the LS1 in 1997 that only left the F-cars with the LT1 for the 97 model year.

Right, you've mentioned before about the TPI powerband, good to know gearing is a possible solution for it. i have a complete setup in storage would like to try it one day on my TBI headed 350 i built.

 

[L31MaxExpress]

I was able to get my hands on the intake manifold today. Casting quality is pretty darn good. A little port matching and sanding roll cleanup should make it more than adequate for my sub 6,500 rpm 383. $368 to my door with fuel rails, mounting hardware, even came with a distributor hold down and a throttle cable bracket. The water outlet is grooved for an o-ring and I think a Caprice TBI water neck may just squeeze in to allow for the stock upper hose if I use a Banjo 90 to AN fitting on the end of the fuel rails. Headed to the shop to grab some stuff here in a little bit.

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[yevgenievich]

I was able to get my hands on the intake manifold today. Casting quality is pretty darn good. A little port matching and sanding roll cleanup should make it more than adequate for my sub 6,500 rpm 383. $368 to my door with fuel rails, mounting hardware, even came with a distributor hold down and a throttle cable bracket. The water outlet is grooved for an o-ring and I think a Caprice TBI water neck may just squeeze in to allow for the stock upper hose if I use a Banjo 90 to AN fitting on the end of the fuel rails. Headed to the shop to grab some stuff here in a little bit.

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Where did it come from? Wondering if there is a bbc version available.

 

[L31MaxExpress]

Where did it come from? Wondering if there is a bbc version available.

Ebay

 

[L31MaxExpress]

Have a little customization to do. FiTech 92mm overlaps the 90mm entrance a bit. True to form the clone has Edelbrocks dumb 4 bolt throttle body pattern rather then the GM one. Will have to grind the 2 bolt holes on the bottom of the throttle body a bit too. Its a known issue using a Pro Flo intake with a GM 4 bolt throttle body. Marine T-Bar map is a direct fit.

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[L31MaxExpress]

One thing I did notice that I really like on this Fitech throttle body is that the lower bore has a bit of a ridge smoothly machined into in that shrouds the lower side of the throttle body at low throttle angles. Under ~25% throttle the air solely enters from the top of the bore, then at higher angles the lower plate starts to open. That should help with some of the jumpiness of a 92mm throttle body on an engine that loves throttle opening.

Also the caprice thermostat housing its both the bottom of the Fitech throttle body and the throttle body flange on the intake. It hits in an area that it looks like should be no issue to lightly clearence. Banjo bolt will definately be needed for the fuel cross over.

I am not sure how I am going to do the fuel pressure regulator yet. It will either be a Corvette filter regulator in place of the stock filter or perhaps a bypass regulator up top. If I do the bypass regulator it will likely get bolted to the ac compressor bracket where the extra hole is between the compressor mounting bolts. In that case my rail will be rear crossover, the thermostat side will get a cap and the fuel inlet will be on the passenger side front.

I actually have pictures from when I mocked up a bypass regulator and Caprice thermostat housing on the 383 when I briefly considered putting a Q-Jet on it to break the engine in. Fuel feed would be to the front with a 180* fitting, the return off the bottom with a 90* fitting and the regulated feed the the rail off the back with a 90* feed facing the passenger side. Same as it would have been and has been before with a carb. The old 350 ran for a year with a 650 cfm spreadbore double pumper on it for a project I was working on using an 0411 to control the ignition and transmission on a carb setup on a LS. I wanted to work the bugs out on a running vehicle before I could tune a couple buddies street/strip cars that wanted to swap to a carb LS engines with a 4L80E, without buying $1,500 in ignition and trans controllers.

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[Supercharged111]

One thing I did notice that I really like on this Fitech throttle body is that the lower bore has a bit of a ridge smoothly machined into in that shrouds the lower side of the throttle body at low throttle angles. Under ~25% throttle the air solely enters from the top of the bore, then at higher angles the lower plate starts to open. That should help with some of the jumpiness of a 92mm throttle body on an engine that loves throttle opening.

Seems a little more complex than a progressive linkage or that lame ass lip GM saw fit to install stock on the throttle blades of all but the 454.

 

[L31MaxExpress]

Seems a little more complex than a progressive linkage or that lame ass lip GM saw fit to install stock on the throttle blades of all but the 454.

The factory small block throttle bodies have a tapered bore as do the LS ones. They just added the lip for even more. CFM Tech used to bore them straight through to the size of the blade.

The linkage on this 92 looks progressive as well. The throttle cam has somewhat of a D-shape to it.

 

[L31MaxExpress]

On to the bad news. It looks like the TPS and the compressor my try to occupy the same area. Just looking at pics and the manifold. I will know more once I mock the intake up on the old 350 in the shop and throw a spare bracket and the old compressor on it. I may have to fabricate a bracket out of like 1/4 " plate steel to move the compressor slightly outboard.