Teutonic Speedracer

iTrader: (20)

Well, I'll start off by saying that I HAVE been reading this post which is kind of related to my question:

https://ls1tech.com/forums/advanced-engineering-tech/397179-how-critical-piston-deck-height-quench-distance-ls1.html

I just got a call from my head porter and he mentioned that my combustion chambers were at 68.8cc which with stock gaskets equates to about 9.7:1 compression ratio....I'm curious to how much I can mill the heads/shrink the head gasket without worrying about PV clearance (if I have to even worry at all). I'd like to get the CR back upto the 10.2-10.7 range. My block has never been decked before, and this is the first time my heads have been off (241 castings). Also, how much can the quench distance shrink before the intake gasket sealing will have issues?

My cam is:
224/224 .568"/.568" 110LSA 106ICL (1.7 rockers, LS6 Valves)

Oh, and I'm on travel for work, so I can't measure my piston to deck height.

Ed Wright

iTrader: (1)

The only way you are going to know is measure it. Don't take anybody's guesses, that could be fatal.

Good luck, Ed

J-Rod

ok, this isn't an advance tech thread, so along with trying to answer it, I'll end up moving it as well to internal engine....

Ok, I'd look at milling the heads. Like Ed said, I'd obviously check everything. Many folks will tell you that a mild cam like what you have doesn't require checking. But, I'm one of those guys who doesn't like to chance things...

Using "generic" ls1 specs...

If your pistons are .006 out of the hole, you can run a .040 Cometic, and your compression will be 10.11.

You could basically do a clean up mill on the heads (.006 mill shrinks chamber volume approximately 1 cc). If you milled .006-.007 off the heads and ran a .040 gasket you'd end up with ~10.23

Mill the heads .030 and you'd be at approximately 63.8cc chamber CR would be 10.73

Mill the heads .052 and you'd be at 60cc chamber. CR would be 11.25

PREDATOR-Z

.020 with .040 gaskets (.034 total) no fitment issues on intake side. PTV "should" be measured (I'll bet it is comfy though)

Teutonic Speedracer

iTrader: (20)

Well, I finally got around to measuring my PTV clearance today. I used a dial indicator. It turns out there was so much on the exhaust that I didn't even measure it (.200-.300"+). The intake though unfortunately had a few degrees where there was only .034" to .042" of clearance. Looks like I will be flycutting about .050" or so on the intake side.

PREDATOR-Z

Did you measure 10* BTDC/ATDC ?

Do you have an adjustable timing chain? If so try retarding the cam 2* (would be better than flycutting IMO)

Teutonic Speedracer

iTrader: (20)

No, I don't have an adjustable timing chain. I checked it throughout the valves range of motion, focusing on the close spots which I mentioned above. Everything to do with timing chain, cam cover is buttoned up. I'll flycut the intakes...not that big of a deal. I'm trying to get a hold of Redmist to let him know he may have issues too. He has the same cam, unsure on valves, milling, and stuff but was going with a much thinner gasket.

BOTTLE ROCKET

iTrader: (4)

TS
How much did you wind up milling, and which gasket did you use??

Teutonic Speedracer

iTrader: (20)

.030 mill, and an .053 stock gasket.