I put some 75 305 heads on my 85 Iroc in late Feb. They were fully ported and polished by a friend's shop for his 327 small block drag car. I put them on and checked everything. All was well but man it pings, bogs and over heats now. I thought that the vaccum lines might be causing my bogging but nope nothing. It can't get out of its own way. I hit the gas and it pops bogs and then goes but slowly. As I am on the freeway it is not a smooth run it is stutering all the way(I can hear it as a I pass other cars).
Now it is overheating somewhat, by that I mean it gets hot after 20-30 minutes of driving.
I am thinking of rechecking the plugs to see if that helps the bogging out. I know I NEED TO GET A NEW PROM but thats outta my range for now. I have seen countless guys run ported heads and not get a performanc prom. I checked the lash, valves, everything yet it still does it.
I am about to take off the heads and throw the stockers back on but before I do that any ideas? I would rreally like to keep the heads on but if not oh well. Thanks in advance.
Paul

 

What is your distributor advance set to, EST unplugged, at idle?

 

Hell I had to advance it as much as 10 degress to make it run at the least crappy. It was based set to 6 degrees unplugged.

 

What harmonic balancer are you running...the one that came on it from the factory, or a replacement?

There are at least two different balancers that will fit on the crank snout of a 305/350, each with the TDC marker in a different location. Buy the wrong one, put it on, and you'll never get the spark advance right.

 

To me it sounds like a sensor is unplugged, maybe bad fuel pressure, TPS not set right, a bad ground, bad coil, got the right firing order. I almost want to put money on the idea that it's something simple. Then again did you consider the compression ratio with the new heads?

 

I had the engine rebuilt back in November. It was a stock replacement balancer. The engine has 5232 on it right now.

 

I would check and recheck and recheck timing and firing order again. Something is not right with the timng if you had to advance it 10 degrees just to get it started. Is it possible you got it one tooth off when you put the distributor back in?