Ok guys, i have a 87 gta, till now i havnt know for sure whether it was a 5.0 or 5.7. I could never reach the block codes. I overheated the car recently, and ever since it has run terrible. It would idle high, and low, my voltage would always fluxuate, somtimes it would lack power, and sometimes it would have alot of power. It sounded terrible and was very neglected. So i m tearing it down to see whats up.

It sucks, its a 5.0 as per the block number, but heres the funny thing. The block number is as follows: 10243878 and according to the web, this is a frekin vortec motor from 1996. WTF?

heres some pics,







So im curious as to what this frekin motor is and wtf did it come out of. Josh

 

Morec.com confirms what you found... '96-98 Vortec 5.0 block. Its basically the same shortblock as what the roller cam 5.0 TPI had, just a different cam. It would have the LT1 powder-metal rods and possibly a steel crank as well, if its all stock Vortec motor stuff inside.

The heads are not Vortecs though.

 

Ill pull the code off the heads tomorrow to find out what they are, im guessing they are the stock 305 tpi heads. thanks Josh

 

They could be TBI heads as well. FWIW, some of the later 1995 TBI 305 trucks had the same block casting as the Vortec trucks and had 187 swirl ports along with a roller cam.

 

My question is I hope you didnt pay alot of money thinking it was
a matching factory GTA, That would make me mad as all hell!

 

Yeah, the heads turned out to be stock 305 081's. Heres the plan to fix this neglected 5.0.

New timing chain
all new gaskets (already purchased)
new valve seals
all new sensors, (i already purchased the tps sensor)
and a new throttle body since mine broke upon removal. Anybody have one?

new vacuum lines
and everything will get a real good cleaning.

Does anybody have any while you in there suggestions? this is my only car so im getting rides to work, i only have 500 to spend, and i should probably get this thing back together ASAP. Thanks, Josh

 

New valve springs. Easily the most neglected wearable part on an engine. Go to GM and get a set of LT4 springs to put in. They are a bit better than what your 305 heads had when they were new, and certainly better than the worn out springs that are there now.

You have to pull the springs off to do the valve seals anyway, and LT4 springs will go right in with no problem and no mods req'd. They are cheap too.

I wouldn't bother with changing all the sensors if they aren't giving you trouble. O2 sensor would be OK, but if your TPS, CTS, etc are not giving you trouble, you're just wasting money replacing them. "If it ain't broke, don't fix it"

 

If you are in to the motor that far, you might want to consider a different cam. You can pick up a used LT1 cam on ebay for $20-$40. You are changing everything else anyway- seems a waste not to change the cam. I just did that swap, and it really wakes up the motor.

You might want to consider a new water pump as well ($40). Depends on how long since the last change, but it is cheap insurance.