I have searched and found only some specifics on the L05 350 engines....hp/ft lbs namely.

I am curious what is the compression ratio on these beasts? I know its not very high and the power stinks but I am using a 1987 A code(heavy duty, whereas the K code is *more powerful*) L05 from a mini-school bus for an engine build. I know the hp is 190 and ft lbs 300(forget at what rpms, its a moot point I guess). But the compression is going to remain the same for my motor unless its too low for my liking then something will change....

I am led to believe the compression is 9.0 to 1 but have seen 9.2 and 9.3 as well....hopefully not any lower than 9.0 .

Anyone have some official stats on these things?

 

I think you have the vin codes backwards. The K is the heavy duty one and the A is the lighter duty. The K is the HO version that puts out its power at a lower RPM. Peak horsepower on the A is 190 @ 4,000. On the K it is 210 @ 3,600. The K has less compression and dished pistons too. My uncles 1994 1/2 truck has the A code 350 and the 1992 1 ton G30 van that I got my 350 from had the K code 350.

 

Here is the information I recently looked at: http://users.apex2000.net/whardie/horse.html

It states the 190hp version as being in the *heavy duty* applications, which the mini bus would be....engine is a 4 bolt, not that it means that was only in the heavy duty vehicles but it helps the case. I originally thought it was a K code VIN but don't recall now, pulled the engine last summer and the bus is long gone....

I do know it has dished pistons but was under the impression the pistons are probably the same in each motor. Feeling I'm getting is the heads are the main difference, the ones pulled off were even more crappy than the standard high swirl heads , 3/8 valve stems, etc....another site lists the 87' 210hp L05 as having 9.3 compression.....which would make me happy. The plan is to leave the current pistons in, engine is in good shape, just dumping the horrendous cam and heads for some Vortecs and a nice Isky roller cam as well as a nice clean up job/seals & gaskets.

Not trying to sound skeptical or that I doubt you but do you know for a fact that the K engine has lower compression and/or different pistons? I'd assume both the A and K are dished. Just trying to get some light shed on it....thanks!

 

My K code had the heads with the 3/8 valves originally. It was also 4 bolt main and came with an advertised 8.3:1 compression. I swapped the heads for 305 TPI heads and then to regular 350 TBI heads that I ported (after I broke a piston while towing)

A is 9.3:1 compression and the K is 8.3. My K came from GM with a roller cam that speced out the same as far as lift as the 305 TPI peanut cam.

I think the A's use a flattop piston with 4 valve reliefs but I cannot confirm that? I know the K does.

 

Was yours a crate motor, or what year was it? The 87' I'm using didn't have a roller cam but it is a roller ready block...not saying that affects the compression but the fact the motor might be different in some ways....hmm.....

 

It was the stock motor out of a G30 before I sent it to the machine shop. Mine was a 1992 engine that was the originol one from the G30. It had a tiny roller cam in it. It also had the 65 lb/hr injectors in it to begin with and a strange TBI with the throttle cable bracket attached to it. It now has a set of 90 lb/hr from a 454 along with a custom chip(took me 4 burns to get mostly right) to match the LT1 cam(was a $25.00 upgrade from a local performance shop), edelbrock intake, and ported 193 heads(done in my garage).