I Bought a 1987 Trans Am In March the person i bought it off of stated the 5.0 had been swapped to a 350 out of a Corvette. I have been doing some work on the car to get it ready for the road. I had a problem with the mass air flow sensor which i fixed but i still have the same problem of the car not wanting to stay running and backfires if you step on the gas pedal. I was wondering if there was an easy way to tell which engine is actually in this car and what the correct timing would be for which ever one is in it. The stickers under the hood are for the 305 and the belt routing shows a sepentine belt i have seperate belts under the hood for the accessories. Any help would be appreciated.

 

You need to bee more spesific... tpi ? tbi? crossfire? carb?

Try seting the base timing to 0* and start advancing from there...

 

It has TPI injection on it. I Forgot to include that in my posting

 

Get the casting number off of the block. It is conveniently located in the most conspicuous and accessible place possible; behind the driver's side head, on top of the bell housing flange.

 

The last 3 digits of the casting number is also on the bottom sides of the block.

 

The only number i can find on the engine block on the back of it by the distributor is a 1 cast inline with the cylinders like the #4 is in the picture. there isn't any other #'s in that location.

 

So... what is it?

 

Tried looking with a mechanics mirror for numbers on the bottom side of the block also unable to find anything that states what engine it is.

 

There's nothing on it "that states what engine it is".

The number I told you about is the casting number of the block. It's definitely there, it always is, the space aliens did not visit the factory and erase the numbers from just your one block, you can count on that. It is the one identifying mark about an engine that cannot be changed (at least, not easily at all). It's easy to look up and find out what bore diameter it had. Since the 305 had one bore diameter all its own, and the 350 had another (which it shares with the 302 & 327, but those are far less common these days), it's usually possible to immediately determine which one of the 2 common ones you have.

I know it's a hassle, but it's the only way to tell, short of a teardown. Get that number, at least the last 3 digits of it if you can't get the whole thing, and post it.

 

Also don't forget that in those years GM started casting displacement numbers in the blocks as well, near the casting numbers. Yours should have a "5.0" or a "5.7" cast in to it on the rear of the block as well, presuming the engine is an '87 up block.

 

Couldn't find any numbers on the block found one on the cylinder head itt crosses to an 87-95 305 engine. I set the timing to the specs under the hood and it still runs rough and stalls and backfires.

 

Your not digging hard enough !!! I had the same problem with the same car trying to find the casting numbers. Like RB says....It's there !!! You have to actually get inside the drivers side engine bay and scrunch yourself right up against the firewall.......take a flashlight and aim it down behind the head till you see the top of the bell housing. You might have to pull some of the wires out of the way to see down there. I couldn't see anything because of the caked on grease and oil, so I gave it a couple of shots of degreaser until I could finally read the numbers. Just takes a little effort and body yoga but is really quite easy to see if you are looking in the right place. The numbers will be upside down as your looking at them....so you will only need the last three numbers to the left of them if you are having difficulty. Post the numbers back here and these guys will be more than happy to tell ya what you have. Happy Hunting !!!

 

That's not caused by the timing. Leave the timing alone and concentrate on troubleshooting the car.

A great place to start is with a tune-up. Spark plugs, wires, cap, rotor, maybe an O2 sensor, send the injectors off to www.cruzinperformance.com for cleaning and flow-matching, and a scan for codes to see if the computer is unhappy with the engine somehow. If the 305 injectors are still in it and it's really a 350 instead, get a set of 350 ones.

After that, if you still haven't found the problem, I'd suggest a compression check.

None of this, inculding the timing, is really significantly different between a 305 and a 350. Besides, if this motor is really which is of course the single most popular lie in the world about a motor swap, it's a 350 with a 683 block just like a TPI 350 out of a Camaro or Firebird, and none of that has anything to do with the issue at hand. Personally, if I didn't personally witness the motor coming out of the Corvette, I would not believe that sucker line; and even if it had been in a Corvette at one time or another in its life, no special spiritual properties will have magically wafted out of the fiberglass and permeated the cast iron and made it into something any different from any other cast iron.

 

Head Casting # is definitely for a 305. I might be able to get a 350 4 bolt main engine with 2.02 heads on it for free from some one i know i was wondering if the transmission will bolt up to it and what other changes i would have to make to get this to work in the car?