I am helping to put a 350 in an 86 and i noticed today that the engine has 601 heads on it. I checked mortec and it is a 87-96 350. It is just a replacement engine from advance auto parts, rebuilt to factory specs. 601 heads are 305 heads with 58cc chambers right? will that make the cr too high?

 

it depends on the pistons used...601 heads are really good when ported/polished though...

 

they are dished. i just wonder why they put those heads on a 350.
i also noticed that i could turn the pushrods when the valves were open. i guess they didn't feel like setting lash. i wonder if they checked the internal parts???????????

 

when the valves where open? even with loose lash, if the valves are open, then the pushrods are tight becuase of the pressure...your guess is as good as mine on that one

 

any guesses on what the cr will be with dished pistons and 58cc heads?

 

I would guess that the 350 will need something higher than 87 octane. It is difficult to know without CCing the chambers and knowing the specs of the pistons and how far down they are in the hole.

If he is hoping to run 87 octane fuel then he would be well advised to use at least a .040 head gasket, and a thicker one would be even better.

If he ports and polishes those 601s, and enlarges the intake valve out to 1.94", he will pick up good hp. Maybe more than 30 hp, which is a nice gain. Tell him to follow the link at the end of my sig for the low down on the 601s

 

went thru that same bad trip with advanced auto!
the pistons had a 31cc dish!compression was about 8.4/1.it was also bored .040 over making it very diffucult to find good pistons to bring the compression up.
now for the good part!
three of the main bolts were finger tight!also one bent pushrod!
advance's policy is that if you can't show proof that a certified technician installed your motor,the warranty is void!
go over that thing with a fine tooth comb before you put it in!
if you haven't installed it yet,consider returning it and either having one built or going thru jasper or g.m.
recon is the company that builds their engines(or used to) and if they still do,keep away!
i have since traded or sold every piece of that motor.
best of luck!
Eric B