ISU-WS6

I've been researching into head gasket thicknesses that I should use to optimize my CR when I put on a set of stock 243s.
Basic setup I will have will be:
-'02 LS1 with ~100k miles
-GMPP ASA cam 226/236 .525/.525 110 LSA
-7.4" Manley pushrods and LS7 lifters
-plus all of the bolt ons that don't matte for this question.

I will be putting a set of 243s from an 80k mile GTO on it. They will be hot tanked/bead blasted at a local shop to clean them up with new seals, etc. OR if funds become available, I MIGHT send them to AI for their performance rebuild. Not looking to have them ported, so don't try to convince me otherwise.
At either shop, they will probably be milled somewhere around .003 to clean the surface and ensure flatness, otherwise "unmilled".
So my questions are should I use the stock .051 GM MLS gaskets and not even worry about it?
-Should I use .041-.045 Cometic or Fel-Pro to tighten the quench and increase compression? (Somewhere around .034-.039 quench is ideal from what I've gathered).
-Or should I just have the heads milled .01-.015 and use the stock .051 gasket?

The bump in compression would greatly help my low end with this cam, somewhere around 11:1 would be great. I only have access to 91 octane around here, with BP probably being the highest quality. Most places are a 10% ethanol blend as well. I calculated somewhere around 7.66:1 DCR with the 10.5:1 SCR 243 rating using one of the Wallace Racing calculators. I've never heard of PTV clearance issues with this cam, even from guys who have heads milled .040. Any input from guys with real world experience would be great.

A.R. Shale Targa

iTrader: (2)

Mill .003"-.005" or so and run the .040" Cometic gaskets for the most efficient quench. Should put you right around eleven to one and run strong with that cam

ISU-WS6

Running the thinner gasket won't affect intake manifold alignment will it?

Darth_V8r

iTrader: (4)

Not at all

ISU-WS6

I didn't think so. I guess Fel-Pro doesn't make a 3.9" bore gasket that I can find, only 4.1 or bigger. Anyone have any part numbers for Fel-Pro 3.9" gasket?

A.R. Shale Targa

iTrader: (2)

Texas speed has your .040" by 3.910" Cometics

ISU-WS6

http://www.texas-speed.com/p-182-cometic-ls1-mls-head-gaskets-3910-bore.aspx

http://www.texas-speed.com/p-2258-cometic-ls1-mls-head-gaskets

http://www.texas-speed.com/p-3839-cometic-ls1-darton-mid-sleeve-3910-bore-040

Which is the "best" cometic to get? I've heard that cometics have problems sealing sometimes if the heads and deck aren't super clean, and fel-pro is more forgiving on imperfect surfaces.

chumaniel

I guess Fel-Pro doesn't make a 3.9" bore gasket

ISU-WS6

Bump.

onebadapple98

iTrader: (1)

Fel-Pro makes a 3.945 bore part number 1160L41 left side and 1160R41 for the right side. I was thinking about using these, and found no one carried them. Would be a special order item . http://www.summitracing.com/parts/fel-1160l041 http://www.felpro-only.com/wp-conten..._Line_Card.pdf

speedtigger

iTrader: (16)

I like the 1160 series FelPros. I have the 1161 041s on my current build.

ISU-WS6

I wonder what (if any) effect the bigger .045 size on the bore would have. Cometics and GMs are .005 bigger than the bore.

hodberta

I've heard that cometics have problems sealing sometimes if the heads

ISU-WS6

The concensus seems to be that if you don't clean the deck and the heads very well, the cometics tend to leak. I'm pretty confident that I can get my surfaces smooth enough, and maybe I will use copper spray too.

ISU-WS6

Does anyone think I will have piston-to-valve clearance problems with this setup? Obviously I should measure, but this install is 4months away and I'm just researching.

redbird555

iTrader: (14)

When in doubt use copper spray. Also if you search most of the issues were with arp bolts for whatever reason? I had everything really cleaan on my last build used new cometics sprayed the gaskets with copper and used arp bolts. never had an issue

ISU-WS6

After researching more and looking through almost every relevant thread I could find, I'll definitely use copper spray. I did notice the trend of having problems with ARP hardware, but I was planning to use the stock TTY bolts anyways.

speedtigger

iTrader: (16)

What problems are these?

ISU-WS6

Leaking coolant/oil from the studs it seems.

speedtigger

iTrader: (16)

That is not a fastener problem. That will either be a gasket problem or a damaged block problem.