reusing composite head gasket?

[snowbeard]

ok, I know I'm poking the proverbial hornet's nest on this one, and I did my searches here, but I was not here for the earliest part of the conversation where we were told if reusing the composite gaskets was verbotten? 

I have what I can only assume is a pretty old composite gasket.  I thought it was solid on first glance, so I didn't replace it, and now my head is due back soon and I either need to order up a new one post-haste, or possibly consider reusing this one?

can I anneal the thin copper faces without destroying the composite? do I need to?

I must say my head leaked between the cylinder and head before, so I don't know why it would be good to reuse this one, but I really just had to ask...

thanks again!

[Brian]

Definitely no.

Get a new gasket. Personally I will only use solid ones and I anneal them even if new. 

[RichardL]

Snowbeard,

I agree with Brian. As you know, I made a personal cause of beating this issue to death. The internal material, asbestos or otherwise, will no longer provide the pushback needed to create an even seal. The thin plates cannot be annealed while the internal material is in place. You can, and will, get a variety of opinion here from those using both solid and composite gaskets successfully.

After a bout of leaking head with a poorly annealed solid gasket, I got a new solid gasket and made a point of doing the best annealing I could. Now, dry as a bone at the barrel/head joint. I also used a good thick layer of Permatex Copper Spray-A-Gasket.
Again, there are people here who will tell you of their successes using grease or, maybe, spit and getting good results. I can't and would not say they are wrong, just that my cylinder head is not leaking anymore (to the best of my knowledge).

Whatever gasket you settle on, I would not waist the time it takes to put together the top end, knowing that you will, almost assuredly, be taking it appart and putting it back together again in a short time. Just get the new gasket.

Yes, I know last weekend's three feet of snow will melt quickly and you need to be out in the Colorado mountains, but I think you will enjoy it more while not leaking from that freshly rebuilt head.

Richard L.

[snowbeard]

you're both right, I will put my order in tomorrow.  thanks!

and while I did get to ski three days in the 44 inches we got over the weekend, I was able to ride my suzi to work in the dry and warm on MONDAY, and all of the week so far!!  that's just how we roll out here! 

[LJ.]

Crikey are you guys out West still getting snow? Anyway... Solid copper gasket for me, I even threw away good composite ones in preference to solid. Take your time with it and job will be a good un!

[RichardL]

Snowbeard,

I'm just Just covering my bases here.

I know it was not the very best way (several others were mentioned in the "Reusing Solid Head Gasket" topic) but I did my annealing with a MAPP/Oxygen torch, because that's what I had. Propane, alone, did not get a good enough glow going. I just wanted to warn that the MAPP/Oxygen combo will melt the copper if you get too close. I had a tiny area of melting that, fortunately, did not ruin the gasket. Get a red glow started and keep it slowly moving until you've finished the whole area.

Having posed this warning, perhaps you could advise what you intend to use so that any advice or warnings for that approach can be offered by other members.

Richard L.

[snowbeard]

oh, good point.  I have both propane and a cannister MAPP gas burner. not MAPP and Oxygen, nor is it adjustable, just a little straight shot propane head made for MAPP.

For a gasket, I figured I'd try to get a solid one, and use the propane clamped in a vice to get the gasket started, and try to reproduce your moving red glow using the MAPP too. 

thanks for the warning, I didn't realize I could melt the copper with the MAPP!!

[beezalex]

Snowbeard,

No, a propane torch will not do a good job of annealing a solid copper gasket (The high conductivity and large suface area let it cool very quickly), but a propane grill will.  I've been annealing copper gaskets with a propane grill successfully for years.  Yes, be careful with MAPP around copper.

[snowbeard]

ah, good idea!  maybe I'll get the old campstove out, sounds like it does a proper job! 

[A10Boy]

I know we all know this, but its worth reminding ourselves that composite head gaskets should only be used with Alloy heads, and used once only. Solid copper gaskets should only be used with cast iron heads and can be annealed and re used.

[RichardL]

A10Boy,

I don't really know for sure if your recommendations for gasket types were once the norm, but now, it seems solid is almost universal. Certainly, used by SRM exclusively for both head materials.

Richard L.

[A10Boy]

Yes, that was the convention back in the day, although I wouldn't question what SRM do with modern copper alloys. But certainly composite gaskets cannot be re-used.

[beezalex]

Not sure where this bit of lore started but..Yea...ummm...even originally, BSA and other makers supplied solid copper gaskets as replacements for machines with alloy heads and barrels.  I can say with a fair amount of certainty both from experience and from a materials science point of view that use together with aluminum isn't a problem.

[snowbeard]

great, I have placed my order for a top end set with Domiracer, should be here by the time I return next week!  solid copper it is, since I know that I will likely do (something to?) the cylinders next year.  for now it was running well enough that I'm not going to mess with them until I get the super rocket together!

thanks again for the help!!

[A10Boy]

Um Err, some background to this.

When I left school in 1975, I did a mechanical apprenticeship and worked for six years with a very experienced and knowledgeable chap who was in his late 40s at the time who was a British Bike enthusiast and expert, and I have a great deal of respect for him and his memory.

He taught me that composite gaskets are better with alloy heads and solid are better with cast heads due to the rigidity of alloy verses cast iron and the compressibility of the gaskets.

Cast iron is more rigid and therefore can compress the solid gasket, while alloy is more prone to warping and heat distortion and therefore a softer [composite] gasket is more suitable as lighter torque settings can be used. That's not to say, solid copper cant be used with alloy heads cuz obviously they can.

I dare say someone will come up with some coefficients of expansion or something to prove this wrong, but that is what I was taught and that's what I believe as it makes sense.

Snowbeard, the main thing is you aren't reusing the old composite gasket and I'm sure solid copper will be great.

Now I've had my rant I'm off for a beer.