Stock 1979 360 with Speedmaster head question

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moparmandan

moparmandan

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Let's say a guy was gonna just throw a set on out of the box. After proper inspection, of course.

What head gasket would you use and why?
Most compression?
Best made?
Guess we'd be going from about 73cc +/- to 65cc chambers?

Thanks!
 
With that low compression bottom end, I would run the thinnest head gasket that I could, which is the Mr Gasket 1121G. The new heads should be good and flat, and if the deck is checked for flatness and is OK, then these ought to seal OK. (And you can always put on some copper coat spray or Hylomar.) Even with the smaller chambers, that old low compression bottom end is not going to push much past 9:1 static CR.
 
Fel-Pro 1008 for head gasket is the most common go to. But, how far in the hole are you pistons? I'm assuming they are 0.030 or more, so no head gasket will get you into good quench territory. You'll need to deck the block and/or replace the pistons to really take advantage of the closed chambers.

There is more to just putting them on, a push rod check and rocker geometry/wipe checks should be in order plus degree whatever cam is in it.
 
fklskv said:
Mopar Performance steel shim head gaskets. They are .020 thick. I run them on my 440.
Click to expand...
Wedge motor only, No embossed steel shim gaskets are available for small blocks unless you use MLS like Cometic's.
 
dano said:
But, how far in the hole are you pistons? I'm assuming they are 0.030 or more, so no head gasket will get you into good quench territory. You'll need to deck the block and/or replace the pistons to really take advantage of the closed chambers.
Click to expand...
More likely close to .100" in the hole for a '79 LA360.....!
 
I run the MLS 27 thou 64cc open chamber heads I don’t think they go any further down than that. You can call and ask.
 
An MLS gasket requires a certain RA on the heads and block so.....

I had a conversation with my machinist this week about the surface ony block and heads. The mls meed a smoother surface than a composite gasket
This engine had run FP 1008 but is getting Cometics.

My advice? Don't mess with the engine. If it runs good why mess with it...I'll leave my opinion of those SM heads out of it.
 
Krooser said:
An MLS gasket requires a certain RA on the heads and block so.....

I had a conversation with my machinist this week about the surface ony block and heads. The mls meed a smoother surface than a composite gasket
This engine had run FP 1008 but is getting Cometics.

My advice? Don't mess with the engine. If it runs good why mess with it...I'll leave my opinion of those SM heads out of it.
Click to expand...
Yes it's the RA that had me ask the question in the first place. If and when I try aluminum heads I would probably stay away from MLS in my case. As to why mess with it? It runs good but could be better. I mean, why do we wrench on anything that runs good? A cylinder head swap is down the list of improvments, though.
 
moparmandan said:
Yes it's the RA that had me ask the question in the first place. If and when I try aluminum heads I would probably stay away from MLS in my case. As to why mess with it? It runs good but could be better. I mean, why do we wrench on anything that runs good? A cylinder head swap is down the list of improvments, though.
Click to expand...
In my usual "run what you got world" I would never bother with what RA the heads have... just drive it.

But in today's "perfection" world where everything must be perfect or I can't sleep, I guess I got a little carried away. I've seen so many race motors fixed with garbage can parts (and run GOOD) that I should have shut my pie hole.

Some if my fixes over the years makes UTG look like Dick Landy Enterprises.
 
nm9stheham said:
With that low compression bottom end, I would run the thinnest head gasket that I could, which is the Mr Gasket 1121G. The new heads should be good and flat, and if the deck is checked for flatness and is OK, then these ought to seal OK. (And you can always put on some copper coat spray or Hylomar.) Even with the smaller chambers, that old low compression bottom end is not going to push much past 9:1 static CR.
Click to expand...
Isnt the 1008 thinner than the 1121?
 
Personally I like the 8553 gaskets they seal and will last forever I know they are a little thinker but how much performance are you really giving up to gaining with a .4 cr difference? I'd rather have an engine that is sealed good and reliable
 
dartfreak75 said:
Isnt the 1008 thinner than the 1121?
Click to expand...
The Fel Pro 1008 is a 4.180 bore .039 compressed thickness
The Mr Gasket 1121G is 4.140 bore with a .028 compressed thickness
.011 isn't much but it all adds up at the end.
 
Krooser said:
In my usual "run what you got world" I would never bother with what RA the heads have... just drive it.

But in today's "perfection" world where everything must be perfect or I can't sleep, I guess I got a little carried away. I've seen so many race motors fixed with garbage can parts (and run GOOD) that I should have shut my pie hole.

Some if my fixes over the years makes UTG look like Dick Landy Enterprises.
Click to expand...
It's good to look at it from both sides. I'm not scared to do it. We're running MLS on my son's 318. And he scraped that with a razor blade. LOL
So far no issuues.
 
dartfreak75 said:
Personally I like the 8553 gaskets they seal and will last forever I know they are a little thinker but how much performance are you really giving up to gaining with a .4 cr difference? I'd rather have an engine that is sealed good and reliable
Click to expand...
It matters more when you're bumping 8 than 10. Lol
 
moparmandan said:
It matters more when you're bumping 8 than 10. Lol
Click to expand...
Yea that's true. With the 8553 I should be at 9.6 with the 1008 It would put me at 10.1 im not aiming for a particular number so the difference to me is the price of the gasket! Lol I will re cc the heads and all that before I put it together to get a better number but I'm happy with 9 point anything lol
 
toolmanmike said:
The Fel Pro 1008 is a 4.180 bore .039 compressed thickness
The Mr Gasket 1121G is 4.140 bore with a .028 compressed thickness
.011 isn't much but it all adds up at the end.
Click to expand...
My bad I had the two backward! I was thinking the 1008 was .28 and vice versa!
 
no fel pro is .028
what nm just said after I wrote the above
the tighter quench (if that's what you are doing) will cover the slight compression bump
no quech and you have to drop at least half point
(excpt with a race only race gas build where you never give it throttle at lower revs and shift down going up hills)
 
Wyrmrider said:
no fel pro is .028
what nm just said after I wrote the above
the tighter quench (if that's what you are doing) will cover the slight compression bump
no quech and you have to drop at least half point
(excpt with a race only race gas build where you never give it throttle at lower revs and shift down going up hills)
Click to expand...
What is quench exactly?? I see you mention it alot help me understand
 
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