Copper headgasket? Good/bad? Thoughts

[racerdave]

If I actually get it built, I'm thinking of 700cc, Shell #1 cam and appropriate valve springs, with rebuilt stock head, maybe just clean up the castings. Omar's 1/2 mile pipes with the inserts on both ends. Fuel used would be 91 octane pump ethanol blend premium. More than likely a base gasket, to keep compression at 10-1 or preferably under? Is copper a good choice on a 700 cc motor?

 

[dwyatt]

I'm running a copper head gasket with stock on my 700cc motor and it's working just fine. I went slightly thinner to bump the compression closer to 11:1 on a race motor with a Lillie head and Megacycle cam. No problems.

 

[I am Carbon]

I have one haven't used it yet.
I have used them in racing engines and they are great and reuseable too.
I am pulling my engine apart in my build and I will be using it.

 

[racerdave]

This is the gasket I cam across on Ebay:
http://www.ebay.com/itm/160681231833?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
It's .032 thick and 78mm bore.

What is a oem head gasket thickness? Is that 78 mm bore gonna work with a 700cc?

 

[I am Carbon]

Thats the one that I have.
I think You could open it up.
But If You ask him I'm sure he will make the one that You will need

 

[danfr]

What type of treatment are people doing with copper head gaskets?

Anyone annealing them?

And is anyone using copper spray-a-gasket or similar?

Cheers

 

[ANLAF]

danfr, there seems to be a range of quality to head gaskets for these bikes. Copper seems the obvious renewable resource. I would have to find out how to do the annealing process.

Welcome to the forum.

Anlaf

 

[grizld1]

To anneal any copper part, heat it cherry red and quench it in water. With a copper gasket, use a tough sealant like Permatex Ultra Black or Ultra Gray. To remove the gasket without damage, thread a needle with monofilament fishing line to get under the gasket, and use the monofilament to cut the sealant.

Dave, sorry this response is way late. I've run a 78 mm. gasket over 77.5 mm. high compression pistons without trouble, but a tad more clearance wouldn't hurt. The OE gasket thickness is about .046".

 

[ANLAF]

Grizld1, what does heating the copper do to it - say a crush washer is annealed, will it return to the shape it had pre-crushing, or ar ethe changes more at the molecular level?

Anlaf

 

[jay760]

I've had a couple of copper gaskets from Copper Gaskets Unlimited, who quite often lists them on ebay, ones been in my 710 for a couple of years with no problems, did put a bit of Blue Hylomar on it,

He will make them to any size and thickness, had it made slightly bigger for the 710 as this is 78mm bore.

I did contact Dwyatt before I bought my first one as I had read he uses one, just to find out if they were any good and how he fitted them.

 

[jd750ace]

Annealing softens the metal by opening up the molecular chain with heat. Quenching preserves this softened state, which allows the softened metal to compress and meld with the variances between the head and the barrel. It is highly recommended to re-anneal copper gaskets before re-using it because copper alloys work harden readily, and there won't be any compressibility left. This is a good reason not to use copper tubing on things that vibrate. The vibration cycle sends the part through compression and tension cycles and hardens it, normally at an attach point or stand-off, and it eventually breaks at the edge of the hardened material. That's how my CJ-5 spit all it's oil all over my feet with a copper line to a direct reading gauge. Broke off at the firewall and I got an oil bath on my feet. Burnt ankles are a BITCH.

 

[racerdave]

Will a hand held torch with mapp gass heat a copper head gasket enough to do as grzld1 recommends?

 

[XS1961]

I tried copper gaskets on my 840's when the 'proper' oversize composite type became unavailable here after the demise of Tony Hall, they always failed after a few months (or weeks!) despite annealing.. Had the same trouble with copper on my Triumphs..

 

[jd750ace]

Will a hand held torch with mapp gass heat a copper head gasket enough to do as grzld1 recommends?

Between 700 and 1200 degrees, depending on the exact alloy. You should be able to get it that hot with map gas, but you have to get the whole thing that hot, so it may require 2 people and 2 torches. Rosebud tips would be good, and a heat sink plate of steel to help keep the heat canned on the bottom of the part. you can pre-heat the steel to around 500 degrees (bright blue) and then lay down the gasket and start working it till the whole thing hits a dark cherry. If you prepare a cold water (metal pan required!) quench and put it off the edge of the steel sheet you can get it in quick and uniform. My dad used a 9 X 13 cake pan for it. The goal is for the part to hit the water as fast as possible after the heat is removed. You can even use the torch to push it in, just make sure the whole thing is uniformly hot, and goes in the water as flat as possible and quick. It'll quench out in about a second and a half, but let it rest for 10-15 seconds in the quench. You want the quenching water to not rise to 80 degrees or more during the quench, but if you have a full cake pan, it can't bring 60 degree water up to 80 with something the size of a head gasket. Part book stuff, part aircraft metalworking for 27 years, part watching old guys who could make an engine run off nearly no resources.

 

[TwoManyXS1Bs]

A few thoughts:

Various thicknesses, can build for specific compression ratio.

The copper is less compliant than composition, mating surfaces must be excellent, will hold compression ratio within more predictable range.

Reusable, dimensionally stable, an advantage in field fixes during races (when not using sealer).

Better thermal conductivity (when not using sealer), composition acts like insulator, risk of dissimilar head/cylinder heat expansion.

We used them in many 2-stroke race engines. Never tried them in 4-strokers, unless factory equipped.