Anybody out there have any experience good or bad with the steel type thin head gaskets by Mr. Gasket ? We are putting 98cc closed chambers on my 0.030 over 396 with L2240 pistons (0.180 dome) We checked the cam lift with dial indicator and looks to be about 0.525", will there be any valve to piston issues with the thin gaskets ?

My mechanic thinks they look like junk and is recommending 0.040 Felpro's, is it worth using the thin ones for the extra compression (est. 10.5 to 1 with thin gaskets / 10:1 with 0.040)

Thanks!

What is your quench going to be with the thin vs the thick? That's more important than the few tenths of compression.

not sure.

Check the valve to piston clearance and quench area with some green florist clay on top of the piston.
Those steel shims are about.016-.018, right?
Just use a feeler gaueg of that size under each end of the head to simulate the gasket so you don't ruin the new ones.
I've run the shims often with never a problem. Just use "copper coat" sealer or aluminum paint on the steel shims for sealer and re-torque the heads after the first couple of heat cycles.

Randy

BBB,

I think you are going to need to know what the piston to deck height is before you can determine what thickness head gasket to use.

Dan

SS3964spd,

As far as we can tell the block has never been decked, and the piston has a 21 cc dome on it, which obviously is proud of the deck at TDC. I have heard/read that the standard in the hole distance is 0.020", can anyone confirm this ? The piston dome height is 0.180", as they are L2240N's.

Thanks!

BBB,

I am also rebuilding a 396 that is .030 over and have done the valve clearance test with a non-decked block and trying to keep the DCR down. I am using the .022 shim gaskets from gmpartsdirect. These I am going to put on with the coppercoat spray and will keep my quench down for pump gas! Here is the info on the shim gaskets. I do not know anything about the Mr. Gasket shims and I was steered to the GM ones by someone else on this board. Hope this helps!

The steel shim gasket you referenced is not for my bore 4.125. Here is the info off GM parts direct:

14015351


Steel Shim Head Gasket 1965-90



This beaded steel head gasket has a compressed thickness of .022". It is recommended for blocks with 4.250" diameter cylinder bores. LS-6 gasket.


Technical Notes: For cast iron heads only; do not use with aluminum cylinder heads. Install with head gasket sealer or aluminum paint. Mark IV use only. **Big-block V8 cylinder head gaskets are available in a variety of materials and thicknesses to suit different applications. When selecting a head gasket, keep in mind the engine's intended usage and the minimum piston-to-head clearance required. Use Gen. V for 1991-92 usage.

Originally posted by BigBlockBeaumont:
SS3964spd,

As far as we can tell the block has never been decked, and the piston has a 21 cc dome on it, which obviously is proud of the deck at TDC. I have heard/read that the standard in the hole distance is 0.020", can anyone confirm this ? The piston dome height is 0.180", as they are L2240N's.

Thanks! =
If the pistons are truly .015-.020 down (the flat area not the dome) you should be fine with the shim gasket.
I haven't used them on the rats but used a lot of FelPro shim ones on small blocks with no issues. (For info these don't use any sealer, they are coated)
Both the head & deck surface need to be pretty smooth for the shim as they are not as forgiving as the composition gaskets in regards to surface finish.
If it looks like the heads were surfaced with a body grinder like some I have seen you don't want to use them :D
I would hold the minimum quench to .030 but you need to check all the cylinders to be sure one isn't higher at this quench. It is best if the piston doesn't smack the head :D

As was posted previously by Randy,, use a sealer like copper coat or aluminum paint.
I personally like spray Hylomar but any of them will work just fine

I just used the .020" (.018-.020" compressed) Mr Gasket gasket your talking about. Worked fine, I did spray both sides of the gaskets with copper coat from the local parts store.

The motor is a '67 396, with 206 heads (96-97cc) and stock valves (2.06/1.72") and I didn't run into any valve clearance issues. cam is a comp cams grind, 226/234 at .050, 270/278 adv, .544/.564 int/ext on 111 lsa.

Also, listen to these guys about the quench! I did alot of research when I built my motor. With a true 10.5:1 SCR, if your deck hasn't been decked its safe to assume .020-.025" down the hole, with a generic .039-.040" Felpro the quench would be way out of the desired area for a "high compression" motor IMO (.065") and would cause more detonation/require a higher octane rating then a motor with a quench in the .035"-.45" with the same compression. I'm running about 10.6:1 is my 396 on the steet now, with about 3000 miles so far no probs smile.gif

Good luck!