North Texas Third Gen Assocation
1982-1992 Camaro and Firebird Enthusiast Club for IROC-Z, Z28, GTA, Trans Am, TTA, RS Formula, SE, LT, Sport Coupe, Berlinetta
kd5icr
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*Please note*
This is my first tech style write up. I will get better as I do them. Please keep this in mind before you rip on me.
What I write is based on what I know as well as several tech books I have. My goal is to help people make sound choices when doing a swap or build.
If you don’t know what you want to get out of the engine you need to think about that
long and hard before you start any build. Money is tight for all of us, so build it smart and build it right.
And the GM small block can last years with little to no problems.
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Just a few years ago parts interchanges on a small block Chevy were simple and uncomplicated. These days however you have to alter your way of thinking and learn some new tricks.
Begin any interchange with one question: are we talking about
a generation 1 or a gen 2 small block? There have been a number of important changes. From 1955 through 1991 Chevrolet small blocks engines have used the same configuration and these are now considered gen 1 motors. In 1992 with the introduction of the 350 LT1 in the Corvette with reverse flow cooling the gen 2 family of SBC has begun. This design had many changes, like the 2 way thermostat and the front mount opti spark dist as well as a cam/gear driven water pump. And because of these changes the timing cover is cast aluminum, so these can not
interchange between The gen 1 and 2 engines.
Include the 1992 (Corvette) to '97 (Camaro) 350 LT1, '96 350 LT4 and the '94 4300 SFI 4.3 V-8. The LT1 350 was used in the 92 to 96 vette 93 to 97 camaro, and the firebird with aluminum heads and in the impala SS with cast iron LT1 heads. The gen 2 LT4 350's came in on the 96 vette. The gen 2 4300 265cid was used on 94 and 95 caprice sedan, wagons and Pickups. (Note 93 Pickups had a gen 1 motor) This is why it is important to know what the engine came out of, It would stink to think you are getting a 350 just to find later when you get it home that you got a 265cid.
Other changes include the harmonic balancer, on gen 1 they have the timing mark on the harmonic balancer, on the gen 2 they do not so as you can see there would be no pointer for timing as it is all done by the computer, called either ECM on Chevy and PCM on Pontiac
So what can we interchange between gen 1 and 2? First know that the gen 2 was dropped from production in 1998. But all is not lost, you can use the roller cam on 1987 and later gen 1's as long as they are machined for a roller cam. The'94 and later L-99 and the 95 and later LT1 have to have a center pilot hole in the cam. The one piece rear seal matching oil pan and crank shaft interchanges with other 1 piece rear seal blocks.
You can also use the 5.7 rods, pistons and valve train parts between gen 1 and gen 2. Engine blocks are different so if you use an aftermarket intake for a carb and rear mount dist, you will have to find and mark the balancer for TDC timing as well as fab a pointer. You will also need a different oil pump drive shaft if you change to rear mount dist and carb manifold.
The Gen 3 small block will not interchange with any thing but a 3rd gen engine but this may have changed, but as of now I have not been told otherwise. So in short you can interchange all the inner parts (cam's, etch) and not external ones (water pump ign dist) from 1st to 2nd gen engines. I hope this helps.
I tried to keep it short and to the point. Writing these things can go on and on. I just wanted to cover the things you will run into.
If you need something made clear to you just ask, I or any of the fine people here
will have or will find the answer.
Bill.
Update supplied by Kevin Hicks
87' is when they started machining blocks for the "spider" that holds the factory roller lifters in place keeping the roller from rotating on cam.
One can however run a roller cam in pre 87' blocks not machined for the "spider" by using after market roller lifters that are paired together and do not need the spider.
Here is an article to reference.
http://www.chevyhiperformance.com/techarticles/148_0307_converting_hydraulic_roller_cam/index.html
Update supplied by Big Jon
"Include the 1992 (Corvette) to '97 (Camaro) 350 LT1, '96 350 LT4 and the '94 4300 SFI 4.3 V-8. The LT1 350 was used in the 92 to 96 vette 93 to 97 camaro, and the firebird with aluminum heads and in the impala SS with cast iron LT1 heads.
The gen 2 LT4 350's came in on the 96 vette. The gen 2 4300 265cid was used on 94 and 95 caprice sedan, wagons and Pickups.
(Note 93 Pickups had a gen 1 motor)
This is why it is important to know what the engine came out of, It would stink to think you are getting a 350 just to find later when you get it home that you got a 265cid.
Other changes include the harmonic balancer, on gen 1 they have the timing mark on the harmonic balancer, on the gen 2 they do not so as you can see there would be no pointer for timing as it is all done by the computer, called either ECM on Chevy and PCM on Pontiac"
The Gen 2 engines were never used in pickups. They used a TBI engine until 1996, when the Vortec engines came out. The Vortec engines were still using gen 1 architecture, but with updated heads and port fuel injection.
The LT4 was also available in a select few '97 Camaros.
Also, ECM (Engine control module) was changed to PCM (Powertrain Control Module) with OBD II. It is not brand specific.
