Squishy, squishy (quench distance)

[Doober]

So I'm getting close to being ready to put the Vortec heads on my truck, but I'm not 100% sure what I should be looking at for quench distance. Currently it's 3.75"x4.020", not decked, and the heads are near 64cc (both current and Vortecs). The current gaskets are stock replacement Fel Pro, I think about .040" compressed. Would I be better off to go with a thinner gasket since the block hasn't been decked? Would I be close to clearance issues? The cam is 212º/218º, .487"/.495", 110º LSA, pistons are flat top/dished w/ 2 valve reliefs, compression with 64cc head is supposed to be ~9.6:1.

I think that's everything

 

[nillabu]

Had mine zero decked (factory was about .025" in the hole) with similiar cam specs. Lift was about the same but alittle more duration. I used the .040" compressed head gaskets and 22cc dished pistons and 67cc open chamber World Products S/R heads. Gave me 9.3 compression. From the looks of your pistons I doubt you'd have a clearance issue.

Steve

 

[tiedyemike8]

Since the block hasn't been decked, and if that is out of the question, I would go with the thinnest gasket you can find. .040" quench would be great to get, but there's no way to get there without decking the block, no matter what gasket you use. But regardless, you are losing some of the benefit of a tight quench area by using dished pistons anyway.

 

[Doober]

I'd read some more about engine dynamics (scr vs dcr, quench, etc.) after I'd built the engine (go figure :roll. It wasn't very easy to find a set of .020" over 3.75" stroke pistons :roll: Plus had I known a little more about quench, etc. I would've probably just gone .030" and opened up my piston options. I've hit detonation with a bit less timing than I expected, so I was kind of thinking there's too wide of a quench area.

 

[SSedan64]

Sure you can, use a .015" Embossed Shim Gasket and .025" Deck = .040" Quench. http://www.summitracing.com/parts/FEL-1094/
You want the Quench tight as possible with those Bowl Dish Pistons. You wont have any Piston to Valve problems either.

 

[Doober]

I kind of guessed I wouldn't have valve issues, being a near-stock type piston. Funny thing is it's $8-9 cheaper per gasket at Autozone/Oreilly's. Are most decks around .025" high?

 

[bracketchev1221]

Since the block hasn't been decked, and if that is out of the question, I would go with the thinnest gasket you can find. .040" quench would be great to get, but there's no way to get there without decking the block, no matter what gasket you use. But regardless, you are losing some of the benefit of a tight quench area by using dished pistons anyway.

I agree with this completely.

 

[tiedyemike8]

Sure you can, use a .015" Embossed Shim Gasket and .025" Deck = .040" Quench. http://www.summitracing.com/parts/FEL-1094/
You want the Quench tight as possible with those Bowl Dish Pistons. You wont have any Piston to Valve problems either.

You could certainly try using an embossed shim, but with the deck not being surfaced (have the heads been resurfaced?) I would be worried about leaks. Those gaskets don't give you much wiggle room.

 

[Doober]

No surfacing has been done.

 

[nillabu]

Sure you can, use a .015" Embossed Shim Gasket and .025" Deck = .040" Quench. http://www.summitracing.com/parts/FEL-1094/
You want the Quench tight as possible with those Bowl Dish Pistons. You wont have any Piston to Valve problems either.

I agree with SSedan64, any time you can tighten up the quench and drive more of the fuel mix toward the flame source, combustion efficiency increases. Yes, pistons are down an average of .025" in most sbc virgin blocks.

Steve