Ok heres the deal, I just bought an 89 Iroc with a replaced 305 TPI, when I got the car it smoked on start up, cool valve guide seals, turns out all the guides were bad to, I had really good compression so it seemed who ever replaced the motor went thru the bottom end and not the top, so we picked up a nice set of matching heads all redone, we took our time and did it in about 3 days, not fun to do with the motor in the car, we get it all back together start it and it runs like crap but no more smoke, now since then i have been playing around with the timing alot seeing where it likes to run, i have a bad manifold and I just picked up another. But here is the situation, before the job the car was set to 4 degrees of timing, the egr and some other vacumm wasnt even hooked up, but the car was fast, now i am lacking serious power, i tried flooring it off a hill and it cant even break the tires loose. I keep checking all the vacumm lines, i am about to fix my manifold, but i dont think a little leak in the manifold would cause all this power loss. Anyone have any idea??? Any input would be much appreciated.

 

There isn't enough info here for us to tell you anything. What number heads did you install? How's the compression now? What's the vacuum at idle? What's the timing now? Any codes set?

 

The valve size were 188's i believe and the last 3 casting numbers were 416, Compression is the same, lowest is 155, highest is 175 average 165, timing is set to 8 degrees right now which is where it wants to run, no codes that i know of but i will double check. I went from metal head gaskets to the fel-pro gaskets and someone told me they increased the cc's of the chamber, but I still dont believe it cuts the power to where my 2.8 will run with it.

 

Some more info on the car, oil pressure is good, engine temp is normal, all vacuum lines (that i am aware of) are hooked up, there are no vacuum leaks, now heres the deal, when I got the car the EGR celenoid wasnt even connected, we hooked it back up as we were putting the motor back 2gether, and its been running crappy, at low rpm's it struggles, it runs rough, and if im in stop n go traffic and i give it a little gas to inch forward it stalls when i let off the gas, and it just lags overall power. Does anybody know if these cars have limp mode in the ECM? I am just scratching my head, ive had a thousand people look at including someone who worked for GM on these cars. We cant find anything to explain this. Please if anyone has any suggestions please let me know, thanks.

 

Well here was the problem, turns out that tan exhaust valve had a bad guide which dropped the valve at an angle, there was a decent sized gap about 1/3 of the outside egde which you can barley make out in the red circle. The machine shop fixed and installed my new springs for free. I started to get the car to run pretty decent before I figured this out, not bad for a 7 cyl car, now with the peanut cam gone and the new cam in this car should run pretty good.