Cylinder Head facing

southpw · Post by **southpw** » Mon Sep 12, 2016 5:55 pm

Good evening guys. I am having a real hard time removing all the gasket material on my head. When I think I have it all removed by using gasket remover and scraper, I let it sit, which then lets it dry completely and I see there is more material left and not a smooth surface. I have gone through 1 and a half spray cans of the gasket remover product.
So Im thinking of getting head faced but unsure how many times the head has already been faced. Is there a spec as to how shallow the bowl can get? I measure the depth at .460" currently.
Brad

4x4M38 · Post by **4x4M38** » Mon Sep 12, 2016 6:31 pm

You've got some rust there too Brad. That won't help.

Wonder if 0000 steel wool with a light oil would help?

southpw · Post by **southpw** » Mon Sep 12, 2016 6:48 pm

Hi Brian. Those rust areas seems to be where the gasket remains. The other areas(where the dotted areas are) are the amooth areas but look like the gasket surface.
I would feel better if I could just resurface it without any issues. Unsure what original head thickness was and what the min thickness allowance is.
Brad

OKCM38CDN · Post by **OKCM38CDN** » Mon Sep 12, 2016 8:04 pm

Have you thought about using a BRASS wire brush on a grinder... brass should not hurt the head but take off the extra gunk...

4x4M38 · Post by **4x4M38** » Mon Sep 12, 2016 9:07 pm

Have it bead blasted, magnafluxed, and checked for straightness.

If all that pans out I think you should be ok.

4x4M38 · Post by **4x4M38** » Mon Sep 12, 2016 9:10 pm

I did check the M38 engine manual. No out of tolerance numbers
for the head. You might find something in one of the civvy manuals.

Take care,

Post by **wesk** » Mon Sep 12, 2016 11:40 pm

I've never seen a minimum height spec for the L134 head.

You are limited on shaving amount by valve contact with the head and excessive compression ratio.

The easiest way to put your mind at rest is to drop the head at the auto machine shop and await their notice to pick it up.

mbullism · Post by **mbullism** » Tue Sep 13, 2016 5:23 am

I have seen discussions on head thickness vs compression ratio. Fairly certain it was measured from top of the rib to mating surface.

Will try and find a link-

ETA: this is not what I was thinking of, but see item #4

http://www.classicmilitaryautomotive.com/tag/l-134/

(it sure sounds like a lot... just passing it on)

Post by **wesk** » Tue Sep 13, 2016 9:23 am

As I said above, Part 2 / Par 4 of that link restates what I said, Over shaving of the head can result in too high a compression and valve interference. Also the info posted there is only what they assume to be original approximate factory head thickness as we do not have any factory published data available. I can hardly imagine that removing nearly a 1/4" from a 1/2" head could be considered an option. Also the head helps remove heat from the engine so the more meat you remove from the head the faster it will get hot and the less heat it will wick away from the engine.

My advice remains the same, take the head to your auto machinist and see what they have to say.

southpw · Post by **southpw** » Tue Sep 13, 2016 10:08 am

Will do. Thanks for all the advice and info
Brad

mbullism · Post by **mbullism** » Tue Sep 13, 2016 1:15 pm

Took me a while to track this down... lol- work gets in the way:

The standard 6.48:1 head dome volume was about 90.5 cc. It’s important to know if your head has already been milled (for reasons I outline later) before you have it milled. You can tell by measuring the thickness of the head from the mating surface to one of the machined head stud bosses on the corner of the head. A standard head will be around 2.1406 inches (plus or minus a few thousanths). If you want to go for the 7:1, then you want the total thickness of the head to be around 2.109 in., which should not be exceeded unless you know what you are doing. (Jim Allen)

The quote above pulled from the links below, and the 2A page link has interesting photos comparing a 6.48 head with a supersonic head and an industrial low compression head.

http://www.thecj2apage.com/forums/going ... 27294.html

http://g503.com/forums/viewtopic.php?f= ... 39#p717838

YMMV...

southpw · Post by **southpw** » Tue Sep 13, 2016 3:19 pm

Thanks for that info. My head thickness measures 2.095" so I may be best to just keep working this material off and not face it again.

4x4M38 · Post by **4x4M38** » Tue Sep 13, 2016 3:38 pm

Sounds like you've got a hot rodded head!

Might try some mineral spirits with your scraper. Or as I suggested
bead blast.

Take care,

mbullism · Post by **mbullism** » Tue Sep 13, 2016 7:30 pm

I'm not saying don't take it to a machine shop, only that you get as much info as possible to make an informed(?) decision is all...

On another note, x2 on the brass wire brush, just watch out for the gold colored wire wheels that are actually stiff steel. A magnet wont lie-