jeef84

Like the title says, LS2 block (stock 4.000" bore), LS1 heads (3.898" I believe?)

I've searched, and from what I've come up with, I need a head gasket with at least a 4.000" dia., but I shouldn't use the using the 1041 due to too much open space. So the question is, should I go with the GM MLS for the 6.0 or the 5.7? Or does it matter? I'm not sure what the sizes are on those gaskets.

99mongooSS

iTrader: (4)

I think you need to go with the bore size of the block...Or at least thats what I would do.

99mongooSS

iTrader: (4)

are you doing a head and cam package? If so call the people who sold it to you.

HEMIETR

iTrader: (2)

Gasket the block not the head. You cannot have gasket in the bore.

405HP_Z06

iTrader: (11)

You need to consider both, fire ring inside either isn't good. Your choice on gaskets, as long as they have a bore diameter bigger than cylinder block bore and cylinder head combustion chamber width.

jeef84

Sweet. Thanks for the great info, guys.

XtraCajunSS

iTrader: (2)

6.0 MLS gaskets unless the chambers have been opened up to more than 4.030"... unless they are early LS1 castings (with the notches in the deck.) In that case you will need early 6.0 truck graphite gaskets. As 405HP_Z06 stated, the gaskets MUST be slightly larger than the larger of the two, the bore or the chamber.

Thanks,
Shane

Black Goat

iTrader: (3)

Quick follow-up.

Is it possible to have the gasket too large for the bore? I've searched and haven't found a definitive answer.

Example: Stock bore LS1 (3.910"), 243 heads w/ a stock 64.45 cc chamber. Can you use a gasket such as the Fel-Pro 1041 w/ a bore size of 4.1"? Is the combustion path fouled up with the slight gap?

405HP_Z06

iTrader: (11)

Within reason, no. The only thing you lose by using a gasket with a larger bore than required is compression. As long as the gaskets are designed to fit within the specifications of the block you are okay.

Cometic offers custom gasket services with a short turn around time. This is an option if you can't find something.

Black Goat

iTrader: (3)

I probably wouldn't need custom cometics. I would go with the standard 3.910" .040 cometic gaskets. My only concern is the price!

That's why the Fel-Pro 1041 is attractive. It's a .043 gasket, but for about 1/3 the cost. The only problem is the bore size. I'm just wondering if that additional space in the oversized gasket bore is going to mess up the combustion path/power production/etc. The amount of additional cc's in the chamber from the oversize gasket is pretty small.

Fel-Pro bore = 4.135"
Cometic = 3.910"

Head gasket volume of the 3.910 bore = 7.87cc
volume of the 4.135 bore = 8.8 cc

This equates to a difference of CR of .01 !

So..... It looks like the only real difference would be in the flame path/travel???

BAD2000TA

iTrader: (6)

Why not just stock GM MLS gasket for the LS2? LS2 uses 243 castings, which were previously installed on the LS1 in the Z06. Shouldn't be an issue. Plus, they're WAY cheaper than Cometics.

Black Goat

iTrader: (3)

Because the stock gasket is .053 thickness compressed.

The cometic is .040 thickness compressed.

The thinner gasket increases compression from 10.34 to 10.67 on a stock-cube LS1 with 243 castings (64.45 chambers).

That could result in 5 hp more at the crank.

If the Fel-Pro .040 gasket would work, that's a pretty good deal for $ per HP.

405HP_Z06

iTrader: (11)

I completely understand the cost issue. The affects of head gasket bore size on flame front propegation is probably an argueable subject; however, for our purposes here there is not an issue that will cause a catastrophic loss in combustion efficiency. The only other small issue is the difference in head gasket technology when comparing the Fel-Pro 1041 v. a MLS. Assuming the gasket surfaces are properly prepared, the MLS is a better gasket than the graphite/composition core of the 1041.

Unfortuneately, there is no perfect head gasket out there. Compromises are made in the interest of product coverage and commonality which ultimately affect the user. I had the same delimma a short while ago on my head/cam swap.....

Black Goat

iTrader: (3)

A few thoughts:

"for our purposes here there is not an issue that will cause a catastrophic loss in combustion efficiency"

- Maybe not Catastrophic, but enough to negate the additional power from the higher compression?

"the MLS is a better gasket than the graphite/composition core of the 1041."

- Where does the Cometic come into this discussion? It's got a reputation for poor sealing quality if both surfaces are not perfect and copper spray isn't used.


Is the bottom line for this discussion that the priority should be placed on proper sealing vs. better quench?

(Sorry to beat a dead horse, but the MLS costs $30, and the Cometics are $180. That's a big difference!)

405HP_Z06

iTrader: (11)

No

I personally think the Cometic got a bad rap from people that didn't properly prepare the deck and head surfaces and subsequently ended up with leaks. Nothing is manufactured perfect and some instances may be attributable to manufacturer defect, but I haven't seen any comprehensive proof either way.

Cometic isn't the only company that manufactures MLS head gaskets for the LS1 engine. The Fel-Pro 1041 is NOT a MLS gasket.


Both factor into the equation and IMHO carry the same weight. The issue is what I stated earlier, to get the perfect combination of both either you can get lucky with the combination and an MLS gasket from a manufacturer you prefer fits the specs you need or you spend more money for exactly what you want.

In the above case, the $30 gasket you reference and the $180 Cometic's are both MLS. The question is whether the gasket dimensions fit your needs.

BAD2000TA

iTrader: (6)

I was faced with this same issue when doing my head/cam swap. The Cometics would have produced better quench, but the price was just way too high for my taste. I felt that the GM MLS gaskets were fine, that losing a few horses that you'll never feel wasn't worth the extra cost. Also, the Fel-Pro head gaskets didn't have a strong following on here. Many had problems. Whether they were good or bad didn't matter; they weren't an MLS design and GM's price was hard to beat. I went with the GM MLS and didn't have any problems.