Hi, I am new to this forum. I just recently purchased a 1986 chevy iroc z. It has 220 000kms on it. The engine has been rebuild 2 years ago. Runs good, but has a slight knock when you give it some gas. I know i have a exhaust leak by the cat. Not sure if this is the source, haven't pursued it much. Just bought the car and its been sitting in the garage since then for the winter. I plan on fixing the knock/exhaust leak and possibly putting in a better cam, instead of the peanut one.

Since i have a 350 avaliable, is it worth bolting my 305TPI intake/heads onto one of the 350's, with a mild cam. Or is it a waste of my time with these 350s and i am better off with the LB9 305. (One is from a 1974 chevy caprice with 75 000 km's and one is from a 1986 chevy van with 60 000kms on it. These are not rebuilt, complete, and in running condition.)

I just want a fun summer driver thats has got some guts.

Thanks Vern

 

Welcome aboard.

A slight knock under acceleration could be a simple ignition timing adjustment, or a problem with a bearing or piston. It seems a bit like overkill to replace the shortblock to solve a pinging problem, when it will do it with the 350 if the timing is again improperly adjusted. However, if it is a bearing or piston, you're on borrowed time.

Typically, the 350 shortblock is a good way to go. The chances of being disappointed are pretty slim if you pick the cam properly. The Caprice engine will be the older style 2-piece rear main seal and driver's side dipstick, so the van engine would seem a more natural choice (doesn't hurt that the van also has fewer km's on it, although it's probably had to work harder during its life).

 

i don't want to replace the engine because of the slight knock. I was just wondering if its worth swaping a 350 block in, with the 305 TPI intake and heads. Or is it a step backwards???? From what i understand, i would need a 350 knock sensor, 350 injectors(24lbs?), new computer(MAF). Not sure. I need to do more reading.