What year engines will work on my '89 Silverado?

[sandlapper]

I have a 1989 Silverado with a 350 TBI engine that is seized.A friend of mine has a 1983 Camaro with a good 305 engine.Will this engine work on my Silverado and if so what will I need to do to it before I put it in?

 

[Wade]

It will not work easily.

The earlier 305 motors in the Camaros had the pre 87 heads with all the intake bolts at the same angle, the intake manifold on your TBI has the 87-95 TBI/TPI bolt pattern. This means you will need a new intake manifold that can bolt to the older pre 87 heads, and an adapter that goes from a carb mounting flange to TBI. That will run you around $200, and having to figure out EGR.
The tune on your factory TBI 350 computer will not run right. You will need a custom chip burned for the smaller engine, or a computer out of a similar year and optioned truck with a 305 TBI.

I would recommend finding an 87-95 350 motor, that way you won't have to deal with that.

 

[wheelman]

The 350 TBI uses bigger fuel injector,s.you would need two 305 injectors switch out.buy a 350 crate motor.it would have the TBI heads.or you could change it all to old school.engine.and carb.do away with fuel injection.that deal would need mechanical fuel pump.and HEI distributor.

 

[Ken K]

Although the 350 ci. in. engine w/ refi may use larger fuel injectors, I would use what you have and try them as is. The ECM will use the O2 sensor(s) to adjust fuel trim to achieve the correct air/fuel ratio. Yes EFI is a little more complicated but using EFI will allow for better cold start, controlling fast idle and warm idle. I have rebuild every carburetor built, even ones not supposed to be repaired, but with you ability, you have to decide how far to go. As a carb guy, who pulled distributors for tune ups on Sun machine, HEI will work great, but vacuum to advance, heat transfer grease under the ignition module and don't forget the ground strap inside the cap, base timing, running advance and proper jet size and adjustments to the carb...I will admit, as emission controls came by the bucket load under the hood, I was glad to see them disappear along with all of the vacuum hoses. Early 80's not so much, but I prefer EFI since working on them in 1976 using a 4 gas analyzer, before scan tools. the 76 Datsun 280Z and Cadillac Seville were the only two on the market with true electronic fuel injection and went from there forward. The rest where CIS injection with sensor plate, fuel distributor and fuel poppet injectors that spray continuously. Those system kept me busy in the early 80's.

 

[c1500deathtrap]

Junkyard shortblock, throw your heads and intake on it.

 

[1989GMCSIERRA]

Just rebuild yours. A rebuild kit isn’t less than 350 bucks. Machine work can’t be much more than 4/500 bucks and that's if you need major machining

Or you can get a brand new crate for 16/1800. I have a 89 with a tbi 350 and it’s starting to burn oil at 395,000 miles. I’m gonna throw a crate 350 motor and rebuild the old one intona 383

 

[Schurkey]

The older 305 is a bad idea. If you go ahead anyway, you'll have to use a flywheel/flexplate for the older engine, in whatever diameter matches your existing starter motor. (153 tooth, or 168 tooth)

 

[c1500deathtrap]

It will not work easily.

The earlier 305 motors in the Camaros had the pre 87 heads with all the intake bolts at the same angle, the intake manifold on your TBI has the 87-95 TBI/TPI bolt pattern. This means you will need a new intake manifold that can bolt to the older pre 87 heads, and an adapter that goes from a carb mounting flange to TBI. That will run you around $200, and having to figure out EGR.
The tune on your factory TBI 350 computer will not run right. You will need a custom chip burned for the smaller engine, or a computer out of a similar year and optioned truck with a 305 TBI.

I would recommend finding an 87-95 350 motor, that way you won't have to deal with that.

Making a 87-95 intake work on older heads is pretty easy. Just open up the hole and use a thick washer under the bolt.... alternatively, search craigslist for and intake for the older heads and buy the 20 dollar adapter plate. Even an old 2bbl intake will work and i can usually find those for damn near free in a junkyard.

 

[Schurkey]

Making a 87-95 intake work on older heads is pretty easy. Just open up the hole

Have you actually done this? I looked at my 1988 intake, oblonging the four holes for older heads would require a long slot, and that slot goes into a hollowed-out area of the manifold (no strength). The hollowed-out area is on the under side, you can't see it unless the manifold is removed.

I didn't think it would work, so I got a different manifold. Maybe I was wrong.

and use a thick washer under the bolt....

Thick, TAPERED washers, or you're going to put stress on the four bolt heads they weren't designed to take.



Going the other direction--modifying an older manifold to fit the newer heads is very do-able, but still requires the four tapered washers. I never found a source for the washers, but I'd expect them to be available...somewhere.

 

[Wade]

Have you actually done this? I looked at my 1988 intake, oblonging the four holes for older heads would require a long slot, and that slot goes into a hollowed-out area of the manifold (no strength). The hollowed-out area is on the under side, you can't see it unless the manifold is removed.

I didn't think it would work, so I got a different manifold. Maybe I was wrong.


Thick, TAPERED washers, or you're going to put stress on the four bolt heads they weren't designed to take.



Going the other direction--modifying an older manifold to fit the newer heads is very do-able, but still requires the four tapered washers. I never found a source for the washers, but I'd expect them to be available...somewhere.

They come with the 55-95 dual pattern manifolds, but I haven't seen them for sale alone. Sort of an oval spacer that goes into an oblong hole. They could only adapt a pre 87 manifold to 87-95 pattern, not the other way around.