Hi. New to this site but not to gen III's. Have a situation that I think I need help with. My neighbor recently passed away and I purchased his 86 Z28 from his estate. He drove the car pretty regular until the trans went toast shortly before his passing. I pulled the motor and trans and have found something I did not expect. The motor is a 5.7 roller block date coded E263 (I'm thinking 1993?), The TPI is an 86 corvette with center holes drilled to use on later heads, it has the not so great 624 heads, Edelbrock headers and the block has been decked (at least it looks that way, no ID # on front tab but fresh machine marks). I have not had a chance to check the cam or see if it was bored but my confusion is that he was running 30lb injectors from a Volvo. ???? Can i just put 22lb injectors back in and run it? I guess I should pull the heads and timing cover but It is my understanding that 30lb injectors are for really high HP motors. Why the poor heads on it then? It seemed to run pretty good when he drove it. Any ideas.

 

Probably overkill on injectors but might open the ecm and see if the chip has been tuned.
If it’s a aum,amu code it’s stock 305 tune . A piggyback green adapter it has some sort of tune.

 

I opened the ecm and the chip has an AXKS code from a stock 305

 

That’s not right axks is a 89 tbi 305

 

That makes sense. He cobbed this motor together and it ran. I just took off the heads and the block was decked to .002 piston in hole clearance and pistons show 4.010 and the heads were reworked. Slightly milled and 2.02 and 1.60 valves. Everything is fairly clean inside, good cross hatch. do you think I can get a 350 chip and run 22lb injectors? I have not looked at the cam yet but I imagine it has also been upgraded

 

What service number is the ecm 1227165 ? The prom letters are confusing.
it really depends on can but a 350 tune would be a good start with 22#hr injectors.
just have to get a custom tune or one from 87 tpi f body with iron heads . Late 88-89 has vats enabled and a different a/c pressure switch.

 

All the numbers on the outside of the case are gone, maybe i will just purchase a new ecm and go with that

 

If the chip access is in the center of the ecm it’s a 1227165, if on one side farther from
The ecm plug it’s tbi 1228746 I don’t see how it could run with that calibration and wiring differences.

 

That is why I am confused. The cam looks more aggressive than stock. My thoughts are that with the 305 chip and all the upgrades it should not run but it did. By the way the chip is on the left hand side of the board. I am thinking of a cam just a little more aggressive than stock and getting a 350 ecm and going from there. I don't want to be doing a lot of diff crap just to get it dependable. If I have to I will just carb it.

 

Sounds like it wouldn't be much more work to extract the cam and look for an identifying part number. That way you have the most information to inform your decisions.

 

I am pulling the cam tonight. I have an ID on the ecm, it is 1228746, these were for tbi not tpi right. Is there a diff? The date code on my TPI is 1988. Looks like all kinds of stuff was thrown together but it did run pretty good.

 

Just checked my intake and TPI part #'s. Both off of an 89 corvette. I did not see an MAP.

 

I’d get a 1227165 ecm and custom tune it would of had to of been in limp home. Surprised the injector driver could work the tpi injectors.

 

Thanks for all the info. The cam is stock so going to get the proper ecm and take it from there.