Question On Piston/Head Combo

[Drg racr]

I picked up a set of KB191 pistons for my 360 at the Indy swap meet. The guy told me he had a .560 cam, stock smog heads and with these pistons he had over 12.1/1 compression and made tons of power. He said the stock heads didn't hurt power at all. I tend to disagree with that. I have a set of stock 360 smog heads (4051's I think). Should I try them or still hunt for a set of J or X heads? 12/1 compression? The domes don't look that big!
The heads I have are stock rebuilds, no porting. I could send them out for a little work, but would it be worth it?

 

[moper]

Those pistons in a non-blueprinted block will be just under 11:1. If any of the heads you want to use have what I've found for average chamber volume they will be larger than 72ccs. Compresion has a little effect on power. Heads and valves have a much larger effect. If it was me I'd take whatever heads you want, have some bigger valves put in with a modern 5 angle valve job, and gasket match them to the intake manifold (don't touch the exh ports). Leave the chambers as big as you can, and run a thicker head gasket. I calculated with the .043 Felpro deal but there are others that are a little thicker for similar money. Then run a cam with at least 240° @ .050 and with careful setup of your timing and carb you should be fine for pump high test.

 

[IQ52]

If he means the stock heads didn't hurt the power because the engine gained power when he went to more compression, that's true. If he means the heads wouldn't give more power if they were ported, that's bologna. The stock 360 "smog heads" as you call them, if properly worked, will make as much or more flow than the J or X head. Any 360 head is as good as a "X" head. You just have to be smarter than your cylinder heads.

Worth it to port them? Hard to say as that is a relative term. Anything done properly will be of benefit horsepower wise. You just have to chose what you can afford.

Go aluminum if you can afford it.

 

[Drg racr]

At this point the 360 is gonna be a cheap build because I'm seriously considering going big block next. I'll talk to a few machine shop guys and see what they can do with the heads I have. If I can spend a few hundred and get these to perform well, I'd be happy.