Optimum Quench for HI-COMP 69 427 ?

[Ironangel]

My JE forged domes are .012" in the hole. They are custom closed chamber domes made for the cast iron 3964290 106cc closed chamber heads. Heads have 106cc combustion chambers. I'm using three layer MLS gaskets that are .039" because that's what George at Clay Smith Cams said I needed. The pistons boast a CR between 13-0 to 13.5.1, that's yet to be determined. I'm running a solid flat tappet cam w/.615 lift, 304 advertised duration, 258 @ .050" w/108 LSA with .020" Howards EDM solid lifters.....Anyway, am I correct in adding the piston to deck clearance (.012") to the Head Gasket thickness torqued? (.039") for a total of .051" thousand's?...Thanks in advance, cams 4 degrees retarded which brought it to 107 LSA ...

[68Gold/white]

.051 is the correct quench distance.

Lots of theories about quench...lots of folks know very little about it.
With a hi compression (make that any engine...)you need the best quench possible. A general rule of thumb is no more than .060, but you are close to that...The smallest recommended quench distance (to be safe...) is .035.
Cometic and likely others make thinner head gasket for your engine. I'd shoot for somewhere between .035 and .040. The tighter quench helps with octane sensitivity and overall engine effeciency...

Decking the block does same thing... Has it been decked??? You likely won't want to deck the block if you've got this thing together.. Decking is a good thing, also, getting head surface square and flat....

Have you clayed up the piston domes, to check the dome to chamber clearances??? another important spec.

I'm guessing this monster is a racer??? Sounds like one!!!

[Ziegelsteinfaust]

Things I have played with is polishing the pistons, and chambers. Or going with coatings. Plus matching your pistons to the cylinder head.

Polishing reduces hot spots do to rough edges, and the like.

The coatings do the same thing but much better. I polished since I had more time then money, and the tools to do it.

Out of curiosity what do you plan to run for fuel in the engine. Also what is your intended use of the engine?

I built a 12.8-1 SBC almost 20 years ago for E85 which never materialized in my area during that time frame. So I ended up running it on a mix of race gas at great financial pain. Yes I really jumped the gun on that one. I would love to do it now, but damn it was loud. That is by my standards even.

[Ironangel]

Thanks for the reply's guys...I do plan to race this motor in a 72 LWB C/10. I plan on using 110 octane race gas, the 454 block was decked .008" and the heads had .005" taken off to clean and true the surfaces. I'm going to install a pair of checking springs on the #1 valves and use a dial indicator with the degreed balancer to get an exact valve to piston clearance on each valve opening and closing event before and after TDC. I de-shrouded the intake sides of the bores, polished up the chambers a bit and the pistons and stainless valves are polished. I still need to find out what the plug clearance is as well. I had plenty of room in there with the 396 22cc domes but these JE 39cc 1.765 domes are crowding the 106cc chambers...Here's a couple of pics...

[Ziegelsteinfaust]

Forgot to ask, but have you thought about running E85 to be a cheaper fuel?

I have heard where you are there is alot more of it at the pumps.

[Ironangel]

I have gave it some thought and haven't ruled the idea out, it would certainly be cheaper at the pump. It would entail a new carb with huge jetting but that may be a real option in the future...As soon as I get all my clearances checked out I'll be ready to drop the motor in the truck. I'm installing a fuel cell and electric fuel pump and installing an electric fan on the radiator...Another pic...439ci BBC I used a lot or David Vizard's recommendations on building a big block on a budget like re-using factory truck 454 connecting rods, ARP main and head studs as well as ARP Wave Lock rod bolts. Grooved the lifter bores and used Howards EDM solid lifters, Comp steel roller rockers with Magnum 80 3/8" push rods. Weiand Track Warrior single plane for iron oval port heads. I didn't have to touch the intake as far as port matching, all eight holes matched up dead nuts. Some of those old school Weiand molds were very good!