What is it for 601 heads and whats the compression ratio for those heads on an LG4?

 

LG4 has normally 8.5:1, depending on the year right? So about 9:1 with 601 heads, as they typically have 52cc chambers vs 58cc.
Head flow is similar to 416 heads. Not many members have flowed them as stock, do a search I think someone has.
They really start to shine when they get ported however.

 

I found an old post that says they flow somewhere around 215 and the compression is 10:1. But I cant find anything to verify that.

 

Being production line castings, they can vary somewhat... typically 205-215 on the intake side, and 150-160 on the exhaust side.

As for CR.... depends what year. The early LG4 had 8.5:1, later ones had 9.5:1 stock, so it really depends what year the motor is.

 

The engine is an 86. I read somewhere that the CR was 10 but read somewhere else it was 9.5.

 

No, definately not 10:1 from the factory. Not going to happen with carb during the '80s.
9.5:1 was on the TPI engines. I would think it would be less. The 601 heads came on trucks/vans, which probably had dished pistons. When you put it on your car, well, then you need to do the math.

 

I found an online dyno and wanted to get an estimate on the hp. It asks for head flow numbers, CR, cam specs and a few other things. Thanks for the info.
http://www.speedwaybids.com/tech/ezonlinedyno.html

 

'86 sounds right for the high compression LG4. They used the same flat top pistons as the L69 and TPI engines, which had 9.5:1 compression as well. Changing to 601s would bump it to roughly 10:1 or so, maybe a little bit more.