O-ringing cylinders to replace head gaskets by Zippers

[gryphon]

I've gathered up most of what I will need to convert my 97 inch 4" bore motor to a 107ci. One of the things I'm trying to decide on is if I should have Zippers machine the tops of my cylinders for hi-temp 0-rings to replace the head gaskets. This will drop my heads by .045" and raise the CR from 9.5:1 to approx 10.2:1. The cost is pretty easy to live with and it's way cheaper than changing pistons and I'd rather not shave the heads by that much since there's no going back and cylinders are cheaper to replace than heads. Has anyone here had this done. S&S says no problem since they figure you can safely drop .06" by shaving the heads.

[Billy]

What is the deck height? If 0, squish clearance will have to be adjusted with the base gasket. You can run a tight .025" squish if you warm the motor before flogging it. This will net .020" tighter squeeze.

or you use a .030 HG and net .015.

gotta have squish clearance

[gryphon]

Squish is a term that I never heard much in the past. Maybe cause it just doesn't come up much with Shovels. I don't know. I would appreciate it though if someone could explain exactly what is meant by "squish".

[FSG]

Squish, have a read here http://www.rbracing-rsr.com/squishcalc1.html

[Buddy WMC]

Sounds like a plan.
BTW, just how mant engines to you have? I'd like to start building a spare for my FXR.

[gryphon]

Using the calculator I come up with a stock squish of .146. So, with the cylinders o-ringed it would reduce the squish to .101 This is asuming I used the calculator correctly. For the measurement from piston pin center to top of the deck I used the same as the 113". Even though my cylinders are .125 shorter, my stroke is .250 shorter so the piston pin sits .125 lower at tdc. If these figures are correct, and S&S is correct this will still give me a very safe margin. My understanding is that no metal is actually removed from the cylinder tops other than what is cut out for the o-ring. The effect of o-ringing would be similar to leaving out the head gasket.

[shovelbill]

gryphon, in '89 or so i ran the o-ring setup in my 80" nutso motor. it had zipper's angle top pistons and headwork. absolutely beat the sh** out of it and never had a problem(with the motor anyway). one less gasket to blow out as long as everything is nice and flat and torqued to specs.

[fergy1940]

gryphon

My old 97 inch was o ringed and never had a problem.

Fergy

[Billy]

gryphon, disregard my previous reply. Your first post didn't mention you were talking about a shovel, I assumed it was an EVO because you posted your question on the EVO board.

[gryphon]

No, it is an evo. I only mentined shovels because squish is not a factor with their heads.

[Hillside Motorcycle]

I'd cc/cut the heads, and gasket/ride.

[stroker800]

  My motor guy likes the O rings,,,my pan has them ,,his Harmann engine too. You could cut in a few Sighn Grooves into the squish area of the heads,,,,,I was thinking of tryin this myself on my evo too lower the comp ratio,,,I might be goin a little deeper and wider than the norm on the groove(have my own ideas)...I do like the O rings and I think my motor guy gets them thru McMaster Carr...
Dave