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Old 05-13-2009, 12:38 AM
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machine shop guys, a question about aluminum heads and head gaskets.

OK, as a retired mechanic i've always done cast iron head engines. the question i have is about head gaskets with aluminum heads. i have installed both composition head gaskets and have installed steel shim head gaskets with KW coppercoat sprayed on them and never had a failure. my questions are-
can you use a steel shim head gasket (.021) with aluminum heads?
should you spray them with KW copporcoat?
if not, which gaskets would you install and how? KW, non KW. i'm looking for gaskets of about .021 compressed height.
any tips about head gaskets (the thinner the better) with aluminum heads is wecome from you machine shop guys. or you old hotrodders with experience with aluminum heads on iron blocks. part #s for gaskets are welcome.

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Old 05-13-2009, 08:09 AM
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Any head gasket will hold good with Cast Block and Alum heads as long the block been resurface. Copper coat or Hylomar will work fine. But you need to retorque the heads after the engine cool down on the first start up.
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Old 05-13-2009, 08:28 AM
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Technically it is not recomended to use a steel shim style head gasket with aluminum heads. Not so much becasue it is thin, but because it is of dissimular metal. When two dissimular metals are in contact, a galvanic action takes place.
(Rust) The weaker metal (aluminumn) becomes the "sacrifical metal" and corrodes. Some racers use the thin gaskets for short term racing where the engine is torn down often but for long term use, you are going to get this galvanic action sooner than you think. For aluminum heads you want to use a head gasket with a softer or preflattened fire ring so the head does not "brinnel"
Get a deep impression in the deck surface from the gasket fire ring.
Felpro makes various gaskets intended for aluminum heads.
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Old 05-13-2009, 11:53 AM
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I used the Felpro 1010 with my Trick Flow heads on a SBC. Go to the Felpro web site for info or give them a call for specifics....Good luck.
ZAPPER
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Old 05-13-2009, 02:20 PM
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Right on the steel shim

Hylomar is the s#%> Another excellent H/G sourse is Cometic.
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Old 05-13-2009, 07:02 PM
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Quote:
Originally Posted by techron
OK, as a retired mechanic i've always done cast iron head engines. the question i have is about head gaskets with aluminum heads. i have installed both composition head gaskets and have installed steel shim head gaskets with KW coppercoat sprayed on them and never had a failure. my questions are-
can you use a steel shim head gasket (.021) with aluminum heads?
should you spray them with KW copporcoat?
if not, which gaskets would you install and how? KW, non KW. i'm looking for gaskets of about .021 compressed height.
any tips about head gaskets (the thinner the better) with aluminum heads is wecome from you machine shop guys. or you old hotrodders with experience with aluminum heads on iron blocks. part #s for gaskets are welcome.
You've got two problems beside keeping hot gases in, that's aluminum moves a lot compared to iron so the head gasket has to decouple that or it busts up. The other is corrosion, so a stable non reactive metal and insulation coatings are needed.

My numeral uno choice is the Cometic MLS5325 for zero decked blocks to stock high blocks. This sucker is three layers of stainless steel with a flouroelastomer coating, they call it rubber, I call it Teflon. This guy is .040 thick.

Next comes some GM gaskets I have two faves and one all-right.
The faves are 14096405 stainless on one side and graphite impregnated composite on the other at only .028 thick. The other is 10105117 stainless foil on the outside and something synthetic on the inside this sandwich is also only .028 thick.

The so-so it's all-right is the 12557236 classic GM cast iron to aluminum sandwich .051 thick, comes from the old L98 'vette needs TLC with some re-torquing after initial use. Not bad, but you gotta remember to visit the head bolts.

Another very nice one is the FelPro FEL1094, now I never used this on a street engine only race so I have no experience as to how long this will keep a seal on a daily commuter that never gets the heads popped till something goes wrong. This gem is a stainless shim with a "rubber" coating on both sides. At only .015 inch thick it's great for helping pump up compression, it doesn't like warped parts, but then who does. It also demands a really smooth finish from the machinist.

Keep in mind you've gotta compute compression ratios piston to deck clearance with these things, a couple are pretty thick, a couple in the middle and one's mighty thin. So watching the ratio and also where the piston is at TDC to the squish/quench deck needs to be on one's mind.

Bogie

Last edited by oldbogie; 05-13-2009 at 07:03 PM. Reason: too many letters in of them words
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Old 05-13-2009, 07:46 PM
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Is the engine a SBC?
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Old 05-13-2009, 07:52 PM
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yes it is cobalt.
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Old 05-13-2009, 08:05 PM
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I use fel-pro rubber coated steel shim gaskets with aluminum heads, no problems.
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Old 05-13-2009, 08:49 PM
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i used a multi layer steel on my aluminum heads, haven't had problems with them. I gotta say though when it comes to gaskets "fel pro performance" is the only way to go.

Racecar100: I know this isn't my post but I would like to know more info on why you re torque the heads.
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Old 05-13-2009, 09:23 PM
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Cometic, ROL, and FelPro are my three go-to brands.

Bogie has it right... that FEL1094 looks like a really fine part. I just installed that same type in a 2.7L Dodge Intrepid and knew it was going out the door and not coming back.

.... well, at least its been three weeks later and its not back yet, anyway.
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Old 05-13-2009, 09:35 PM
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well, at least its been three weeks later and its not back yet, anyway
LOL not for that anyway. The dreaded two seven...
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Old 05-13-2009, 09:52 PM
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Quote:
Originally Posted by Deez
LOL not for that anyway. The dreaded two seven...
Tell me about it... any engine that you have to pull the heads to change the knock sensors is not my friend.

But I am pretty proud that I took an engine that had been sitting outside for three months with no oil pan, gave it a bottle-brush hone rebuild, new bearings, and a good cleaning, and its still running strong after three whole weeks.
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Old 05-13-2009, 10:49 PM
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i the past on head gasket replacement jobs with aluminum heads we always have used the ordinary oem replacement fel pro blue head gaskets and never have had any issue at all.

razor blade the gasket surfaces real good and thats it

no problem at all.


have fun
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