Vortec chamber size?

[88bluestar]

My EQ vortec hybrid heads were cced at 63cc but to keep decent quench(squish) it would require getting to 66cc. Is it possible to roll back the chamber edges enough to account for 3cc or would I better off keeping the chamber intact and running a shim with my head gasket?

4.030 x 3.50 stroke
4.125 head gasket bore .039 thickness
-4cc piston
0.015 below the deck

Rule is under 10.0:1 compression

[CGT]

My EQ vortec hybrid heads were cced at 63cc but to keep decent quench(squish) it would require getting to 66cc. Is it possible to roll back the chamber edges enough to account for 3cc or would I better off keeping the chamber intact and running a shim with my head gasket?

4.030 x 3.50 stroke
4.125 head gasket bore .039 thickness
-4cc piston
0.015 below the deck

Rule is under 10.0:1 compression

Are you saying that you want to decrease your piston to head clearance, but keep the compression ratio the same?

[frankthetank]

Sounds like he is trying to increase chamber volume 3 cc to get under 10 to 1. at 10.3 or so at the moment.

[Newold1]

What thickness head gasket was installed when your cc's were measured at 3cc.

A thicker head gasket increase could lower compression but if it gets to thick it starts hurting quench between the head surface and the edges of the piston.

Another solution if the engine is out and can be broken down would be to pull the pistons and have the valve reliefs cut by someone like Rebco to increase the increase the overall cc's and not affect quench.

www.rebco-machine.com

[88bluestar]

Trying to figure a balance between quench/squish and get compression ratio as close as possible to max for my rules.
Figured .039 head gasket and .015 shim plus .015 below the deck to make a total .069 and keep the vortec chamber intact so the chamber stays as efficient as possible. Does this sound like the best route? Only plan to smooth any sharp edges on the chambers but nothing beyond that. Heads were cced by a shop

[Newold1]

A .069" gasket will pretty much kill the quench. Don't round the edges of the chambers unless you are softening things for nitrous. Just have the reliefs in the piston tops joined with a trough instead of seperate reliefs and you drop the compression and kept the quench with a .039" gasket.

[88bluestar]

Requires a rebalance?

[Newold1]

No , the piston cut will only probably remove 1-3 grams and that won't affect balance enough to change the existing balance and all pistons will still be matching weights.

[mag2555]

Heck, I would go for matching even 5 more CCs into the chamber which would let me run a longer plug closer to the center of the chamber!

[88bluestar]

Heck, I would go for matching even 5 more CCs into the chamber which would let me run a longer plug closer to the center of the chamber!

?

[88bluestar]

Unfortunately after looking at the piston which is a Lightweight type, it’s molded as such that any such machining would not be possible. SRP 157072 357 4.030 3.500 6.125 -4cc
Have no choice but to shim it, budget dictates such.

[Keith Morganstein]

The OP wanted to know if they can remove 3cc from the chamber.
Why not? (If rules permit grinding in the chambers)

OP, take a look at the chamber photos in this Larry Meaux thread.

https://www.speed-talk.com/forum/viewtopic.php?t=22571

[88bluestar]

Keith, I'm just wondering if Ill be able to get 3cc of material without having to really roll back edges everywhere. They are already put together as you can see in the pic.

[88bluestar]

pics

[88bluestar]

The OP wanted to know if they can remove 3cc from the chamber.
Why not? (If rules permit grinding in the chambers)

OP, take a look at the chamber photos in this Larry Meaux thread.

https://www.speed-talk.com/forum/viewtopic.php?t=22571

Do you think a clean up and roll back of the spark plug boss can make 3cc?