350 TBI interchangability

[Marcos Beltran]

I have a 95 chevy with a v6 tbi that i want to upgrade to a V8 350 tbi. I have a tired 350 tbi with over 250k miles on it and i have an 88 camaro 350 long block. Are the long blocks the same? I had a buddy years back pull out a stock 305 tbi ojt of his 89 firebird and put a 94 truck 350 tbi in it and claimed it ran well. Is that possible?

 

[PlayingWithTBI]

The 350 has bigger injectors, of course. You may find your TPS connectors are different but, you can buy an adapter for that. Make sure you the same number of vacuum ports too. Or you can simply swap injectors from the 350 to the 95 4.3 and ship it

 

[Marcos Beltran]

The 350 has bigger injectors, of course. You may find your TPS connectors are different but, you can buy an adapter for that. Make sure you the same number of vacuum ports too. Or you can simply swap injectors from the 350 to the 95 4.3 and ship it

Let me clarify a little better. I have a suburban parts truck that has a complete 350 tbi in it but it has well over 250k on it. I also have a 350 tuned port out of an 88 camaro. The tuned port parts are long gone but i still have the long block. My question is could i transfer all the parts off the 350 tbi and put them on the long block camaro 350 and replace the v6 in my stepside.

 

[PlayingWithTBI]

The tuned port parts are long gone but i still have the long block

Ahh OK, I don't think the TPI heads have the same intake bolt pattern as the TBI but, I may be wrong... I guess you can always get a 4BBL intake manifold and a TBI adapter plate.

 

[Schurkey]

Ahh OK, I don't think the TPI heads have the same intake bolt pattern as the TBI but, I may be wrong...

Fairly sure the heads are NOT the same bolt pattern as the TBI intake--the center two bolts are at a goofy angle on the TBI.

I guess you can always get a 4BBL intake manifold and a TBI adapter plate.

I did this on my '88 K1500. Getting the EGR to work was a nightmare; I had to use a home-made adapter plate on top of a store-bought adapter, otherwise the EGR valve interferes with the IAC valve.

Had to make a simple adapter bracket to bolt-up the ignition coil.

Had to use some hardware-store pipe thread adapters to get the brake booster vacuum tube, and the quick-coupler for the heater to work. The booster vacuum tube had to be cut, re-bent, and generally dicked-with.

Needed a TBI-to-Q-Jet manifold adapter to mount the throttle body. Good news was that my chosen manifold (same unit used on the ZZ-series crate engines) places the mounting pad at almost exactly the same height as the TBI manifold--just a little bit higher and a little farther forward. I didn't need to replace the throttle cable, trans TV cable, or the cruise control cable. I did have to re-adjust the TV cable; and the bracket that holds those cables fit the new manifold just fine.

The alternator support strut and the belt tensioner support strut fit perfectly. There's no place to attach the A/C compressor strut, and I had to get creative with the mounting for the MAP and ESC controller.

Yeah, it's do-able, but the EGR especially is no fun at all.

If I were doing this again, I'd buy the Summit aluminum TBI heads, and use the TBI manifold instead of using the older aluminum heads (old-style intake bolt pattern) I had on the shelf, and the ZZ manifold.

 

[Frank Enstein]

Bolt it in and go. The cam might not play nice with the TBI computer.

The intake manifold bolt pattern changed in 87 EXCEPT for corvettes. They retained the older bolt pattern up through 1991.

 

[Frank Enstein]

A Brief History of Small Block Chevrolet Cylinder Heads


1st Design 1955 to 1986

Perimeter Bolt valve covers.

Top valve cover bolts are closer together than the bottom bolts on 1955 to 1958 heads.

Six intake manifold bolts per head 90 degrees to the gasket surface.

Many heads made prior to 1972 Have no accessory holes.


2nd Design 1987 to 1995

These are NOT Vortec heads.

Center Bolt Valve Covers.

Six intake manifold bolts per head center two straight up.

Front and rear bolts remain 90 degrees to the gasket surface.*

*Exception 1987 to 1991 Corvette Aluminum (L98) heads

retain the 1955 to 1986 bolt pattern For the intake manifold.



3rd design 1992 to 1997 LT-1/LT-4

Center Bolt Valve Covers

Six bolts per head for intake manifold 90 degrees to the gasket surface.

No water or exhaust crossover passages "Dry Intake Manifold".

LT-4 has raised intake ports.

Raised "D" shaped exhaust ports.



4th design 1996-1999 Vortec Truck

Center Bolt Valve Covers

Four intake manifold bolts all straight up no bolts in the center.

Raised intake ports based on the LT-1/LT-4 design.

No exhaust crossover provision.

Conventional square port exhaust.

 

[L31MaxExpress]

It will bolt right in. Will need to set the timing at 6-10° BTDC with the timing wire disconnected. The TPI heads require ALOT more timing than the swirl ports. My old TBI ran great with a LT4 cam. L98 cam is smaller than a LT1 or LT4 cam and also came in the TBI 9C1 cop cars.

 

[1993GMCC2500SLX]

Fairly sure the heads are NOT the same bolt pattern as the TBI intake--the center two bolts are at a goofy angle on the TBI.


I did this on my '88 K1500. Getting the EGR to work was a nightmare; I had to use a home-made adapter plate on top of a store-bought adapter, otherwise the EGR valve interferes with the IAC valve.

Had to make a simple adapter bracket to bolt-up the ignition coil.

Had to use some hardware-store pipe thread adapters to get the brake booster vacuum tube, and the quick-coupler for the heater to work. The booster vacuum tube had to be cut, re-bent, and generally dicked-with.

Needed a TBI-to-Q-Jet manifold adapter to mount the throttle body. Good news was that my chosen manifold (same unit used on the ZZ-series crate engines) places the mounting pad at almost exactly the same height as the TBI manifold--just a little bit higher and a little farther forward. I didn't need to replace the throttle cable, trans TV cable, or the cruise control cable. I did have to re-adjust the TV cable; and the bracket that holds those cables fit the new manifold just fine.

The alternator support strut and the belt tensioner support strut fit perfectly. There's no place to attach the A/C compressor strut, and I had to get creative with the mounting for the MAP and ESC controller.

Yeah, it's do-able, but the EGR especially is no fun at all.

If I were doing this again, I'd buy the Summit aluminum TBI heads, and use the TBI manifold instead of using the older aluminum heads (old-style intake bolt pattern) I had on the shelf, and the ZZ manifold.

Tuneport motor has a specific intake manifold bolt pattern and center 4 bolt holes on the tbi are a specific type they are angled not straight, and a pain in the ass to line up.. other than that don't use the distributor from the suburban the tuneport f body motor is roller cam,you don't want those problems trust me lol.. other than that and the ignition coil bracket the short blocks are pretty close.