i am rebuilding a 360 and the heads i took off the motor had different casting numbers. one 3769974 the other 3671587-4. i know the valves are the same. this motor has ran before but are there any major problems with new mods(.040 over, cam, higher compression piston)?

 

your heads are the same valves the first is 75-76 yr and the later is 76 yr most likely the vehicle was assembled at the factory with the heads maybe they where running low it's not a big deal for the factory, or the heads where re-manufacturer and one was replaced.
have your machine shop double check to make sure one wasn't modded

 

There is no "problem" with the mods you have in store but it will require a mock up. Always check for piston valve clearance.

 

so i got the heads back and i need to get new valve springs. i cant find specs on a stock replacement. not sure of what to get. cam is a 278/288, Lift .421/.444... not going to be a high reving engine.

 

I use this one with the 901 springs, retainers and locks recommended in the truck and very happy.

http://www.compcams.com/Company/CC/c...?csid=625&sb=2

 

Is that cam a comp if so get the recommended kit
when i bought my comp cam K20-418-3 it had everything needed except the push rods and i also ordered those from comp

 

summit racing brand cam

 

send it back your going to get lousy mileage and low power
the MP purple cam 284 dur 488 lift
the same lunati cam advertised Duration (Int/Exh): 276/284
Duration @ .050 (Int/Exh): 234/242
Gross Valve Lift (Int/Exh): .513/.533
LSA/ICL: 110/106

hell even my cam with shorter duration has a higher lift
if you haven't installed it return it summit is great
and get a kit

 

its already installed. im just trying to find out what valve spring to use.

 

Comp Cams 901-16