Fel Pro 1020 or Cometic MLS

[aj]

Soon bolting heads on.  Iron heads and block. Machine shop sent Cometic MLS (.060 x 4.400) 5 layer head gaskets that puts CR at 9.7.   It occurred to me I could also use FP 1020s (.041) that would result in 10:1.   That said,  I’m looking for most fool proof combo...not max HP.   The 1020 seem simpler which is good thing for my simple mind. 

I believe either route puts me in the realm of 93 pump gas. 

I’ve read through posts re: the Cometics and seems the benefit is for high CR or forced induction scenario (definitely not me).  I’m not sure why machinist set me up with Conetic but I assume it was to get the CR well into the mid 9 range...although it seems 10:1 would do 93 octane.

Questio 1  for the resident experts:  FP 1020 or Cometic MLS. 

BTW: machine shop put smooth surface on block and heads.  I noticed on block the area directly between cylinders to very smooth...smoother than rest of surfaces (which are pretty darn smooth). 

Question 2. Can the FP 1020 be used where the RA is smooth enough for Cometics.

TIA

[blykins]

How far are the pistons above/below deck?

[aj]

Ranges from .007 -.011 below deck

[blykins]

Without knowing the entire combination and assuming the entire system can handle 10:1, there’s no way I’d run a .060” gasket with the pistons .010” under. 

[machoneman]

Quench distance would be poor too (.060 + .007 to .011)

[aj]

Machine shop (Kuntz Co) advised to keep CR down around mid 9’s since build is for longevity rather that max performance.  Perhaps that’s reason for .060 gasket and .010 in the hole.  At any rate,  I’m not married to Cometic gaskets if I don’t need to be. 

[blykins]

A .070” quench can be worse than high compression.

Post up all your specs and we can discuss.  I don’t see any reason why the 1020 would not be a wise choice.

[blykins]

With 10:1 and that cam, I would feel comfortable. 

Cometic makes a 4.360" x .036" gasket.  I would even consider running that over the 1020, although paying $180 for another set of Cometics when you have 1020's on the shelf would be a tough call.

With a 1020, you're looking at around .048" quench distance.  You're fine there.  If you wanna go pick some money off the tree, I would look at the .036" Cometic, which would put you at around .043".  Not necessary, IMO, but it's a possibility.

[Falcon67]

I only have one specific experience with Cometics and have no reason to use them again.  I'll stick with Fel-Pro performance items.  Otherwise, echo Brent.  Too much compression distance could/will make issues with potential detonation worse.  Keep it tighter than .050 and work the other items in the build. 

[chris401]

With 10:1 and that cam, I would feel comfortable. 

Cometic makes a 4.360" x .036" gasket.  I would even consider running that over the 1020, although paying $180 for another set of Cometics when you have 1020's on the shelf would be a tough call.

With a 1020, you're looking at around .048" quench distance.  You're fine there.  If you wanna go pick some money off the tree, I would look at the .036" Cometic, which would put you at around .043".  Not necessary, IMO, but it's a possibility.

The one set I checked was .041 as advertised. What is the typical variance on 1020s?

[blykins]

The .048" I was referring to was total quench distance.  That includes the gasket thickness and how far the pistons are in/out of the hole.  His pistons are .007" down.

[aj]

I’m going with the 1020s and will try to sell the new/unused Cometics MLS .060 at a bargain price.  Thanks for advice.