Alright guys, i have done searches but i need personal and exsperienced opinions. I recently aquired an 85 Trans Am shell with the performance suspension package. It had an LG4 i think. It will be mainly a cruising car that will be taking long distance trips. What i need to know is some of the most basic of questions about chevy engines which i dont have experience with exept for V6's: What block would be best-305,350,383? With your opinion on blocks please let me know what heads you use, cam's, rockers, Carb or FI? Any info about your knowledge with these engines would be appreciated. Remember, gas is an issue since i will be traveling mainly freeways but i am ok sacrificing milage for performance. Thanks guys. Anthony

 

FireDragon,

I'm not THAT experienced but I think I can supply SOME good/valid information. The eighth digit of the VIN will tell you what the motor WAS.

Engine Codes 85-86
2 = 151 ci L4 LQ9 (1985)
1 = 173 ci V8 LB8 (1985)
S = 173 ci V6 LB8 (1986)
F = 305 ci V8 LB9
G = 305 ci V8 L69
H = 305 ci V8 LG4

My son an I are currently installing a 350 into the location a 305 was. Ours is a LOT more complicted as we're going from cross-fire to CC Carb (Computer Controlled). That is our personal preference and since we need to change the entire wiring harness anyway..... we could do as we pleased.

However, you will find that most of the guys on this board would prefer the TPI first choice (Tuned Port Fuel Injection) or TBI (Throttle Body Fuel Injection) over the Carb.

From all the input we've received on the boards it seems clear that changing from 305 to 350 is seamless. However, the 383 is apparently NOT as compatible with the computer control and one of the other guys will have to explain those differences. There will be a number of different opinions on the choice of block and heads and I don't have enough knowledge to highlight the differences. We chose a 350 to gain few Cubes and HP over the 305 and use a stock computer system that didn't need lots of programming to handle the change.

If you have the original wiring harness in good (or repairable shape) IMPO (In my personal opinion): Stick with the intake system that came with the car and upgrade to the 350. You may still have emissions to worry about on an '86 in your state and that will make inspection MUCH MUCH easier. It is also my understanding that the TPI and TBI can be a "little" better on fuel than a carb set-up.


The best I can do..... HOPE IT HELPS.

 

EFI is going to be more fuel efficient, whether TBI or TPI. It really needs to be understood, though, what rigor of emissions inspection you will need to comply to. If you go with a complete system from a donor car, that is the best way to accomplish the swap. However, you will need to assume some modifications to either system for best performance, and assume you need to learn to do your own PROM tuning.

If the engine was in fact originally an LG4 or L69, and the harness hasn't been chopped up, it isn't too hard to find the parts necessary to get it going again. That would be the least hassle and probably the least expensive to do, would give great power regardless of engine, and decent fuel economy.

For a block, I'd look for an '87-later one-piece rear main seal, roller cam 350 block. You can keep it a 350, or make a 383 out of it. Roller cams are more expensive than flat-tappet, but arguably better. Get a computer-compatible type from Comp, Crane, or any other "major" cam manufacturer. Factory roller lifters are re-usable if the engine was treated to decent maintenance.

Heads, if you don't have anything to start with, aftermarket replacement heads such as World Products or Protopline are relatively inexpensive, well-equiped, and perform well. Comp Magnum rockers are pretty good.