Knuckle head gaskets

[46CHF]

What are thoughts on using copper head gaskets on 74” knuckle motor

[T. Cotten]

What are thoughts on using copper head gaskets on 74” knuckle motor

Just from experience, 46CHF,...

I would seriously avoid the "corrugated" ones.

(Actually, I would avoid copper altogether.)

....Cotten

[bobphd]

I have been riding 61 and 74 knuckleheads for 45 years now. I still put about 10,000 miles a year on and in the past had 20,000 mile years. The only time I had a head gasket problem on a 61 was when I had 36 4 fin cylinders on my 40 motor and used 5 fin head bolts. I didn’t know at the time there was difference. The too long head bolts bottomed and tightened without completely tightening the stock type head gasket. I got about 500 miles from home on a break in run when one of the front head bolts broke and the head gasket blew. I was in Canada just north of Warroad Mn. I made it to Roesou Mn. and found a guy who worked at the Polaris snowmobile factory. It was Sunday but he called a machinist friend who came in and made me a couple of head bolts. I had a spare head gasket and it took all day but got the bike back on the road . I finished the ride in the next few days putting about 2000 miles on without further problems.
74s had have been more head gasket problematic for me though. In the past I used stock type and blue Teflon type and probably have blown at least 6 over the years usually on long road trips. About 10 years ago I blew one on the way to the Knucklehead Company anniversary party in January. I always carry a spare so was able to replace it at a gas station and make it to the party. Someone there told me about using copper head gaskets so I started using them. I have been using them exclusively on both 74s and 61s since and have not had a problem in over 100,000 miles of real world use.
Everybody has there own opinions and preferences but this is what works for me in keeping my old junk on the road.

Bob Patza

[govmule84]

I have used the graphite ones with the blue PTFE coating on mine and it seems to work out OK. I'm not putting near as many miles on as Bob is up there, though.

I find it a little tricky to do those with the engine in situ simply because of the lack of fire ring makes it easy for the gasket to slip around!

I use a torque wrench, and even though no values are supplied for Knucks, I take a little solace in knowing the heads are tightened at least similarly at each fastener. (Yes, this part is often a pain in the ass.) I take it in steps, too, usually approaching final torque in three stages. I also believe in a torque check and retorque after a few heat cycles.

I know you didn't ask all that, but I feel that the method is just as important as the product and in many cases more so. FWIW, I use copper gaskets in my flathead, and they seem to do just fine, but I think with the smaller sealing area of the OHV, I would not use them there.

[T. Cotten]

Did the MOCO make copper Knuck gaskets, Folks?

(I never encountered any real ones, just "Felpro-style" asbestos composites.)

Thanks in advance as always,...

....Cotten
PS: Next question: Do you want the gasket to conduct heat, or insulate?

[46CHF]

That’s a good question Cotten what are your thoughts on insulation or heat transfer

[T. Cotten]

That’s a good question Cotten what are your thoughts on insulation or heat transfer

If I had an easy answer, I wouldn't ask it, 46CHF!

....Cotten

[Chris Haynes]

The MoCo always used copper head gaskets until the war time restrictions on copper during WWII came into effect. It was at that time that they started using asbestos gaskets. Copper gaskets can be annealed and reused. A thin later of aluminum spray paint makes a great sealer.

On a side note I recently bought a 1921 Ford Runabout. I was surprised when I pulled the head and found an original FORD script copper head gasket still in use. Being as it is only 99 years old I am going to reuse it.

[T. Cotten]

The MoCo always used copper head gaskets until the war time restrictions on copper during WWII came into effect. It was at that time that they started using asbestos gaskets... .. A thin later of aluminum spray paint makes a great sealer...

That's great info, Chris!

But why should they need a sealer?

Insulation?

Why didn't they go back, when it was surplus?
Just wondering, since they obviously went to ordinance brass for manifolds and stuff.

....Cotten
PS: I couldn't get some 'corrugated' (probably Eversure) coppers to seal, with paint of course,... cold. Never fired.

[41craig]

I've always liked the asbestos clad steel gaskets. They seam to be more forgiving on not so perfect gasket surfaces. I bought a bunch of these type for Big Twin Flatheads when Ballak & Co. went out of business in the '70's.
Craig

[ihrescue]

The MoCo always used copper head gaskets until the war time restrictions on copper during WWII came into effect. It was at that time that they started using asbestos gaskets. Copper gaskets can be annealed and reused. A thin later of aluminum spray paint makes a great sealer.

Chris - When I saw your mention of annealing a copper head gasket I did a browser search on the keyword "anneal copper head gasket." One item that turned up I think is interesting in that this Brit bike enthusiast had even new copper head gaskets that were somewhat hardened and he recommended even annealing new copper head gaskets. I for one would like to hear how others react to his observations and comments. Here is the link https://www.classicbritishspares.com...ys-anneal-them

Mike Love

[ihrescue]

That's great info, Chris!

But why should they need a sealer?

Insulation?

Why didn't they go back, when it was surplus?
Just wondering, since they obviously went to ordinance brass for manifolds and stuff.

....Cotten
PS: I couldn't get some 'corrugated' (probably Eversure) coppers to seal, with paint of course,... cold. Never fired.

Tom: One reason I have heard for using the spray lacquer with suspended aluminum dust in it is that the aluminum fills in and helps seal any irregularities between the head gasket and the head. A friend of mine who had been a H-D master mechanic for 30 some years swears by it to give that extra sealing edge. Of course the use of a soft metal like copper and torquing was also probably to account for the irregularities in cast iron. It would be interesting to know if H-D ever had a service bulletin to recommend this procedure.

Mike Love

[T. Cotten]

It sure didn't help the 'corrugated' gaskets at all, Mike!

Paint's good for composite gaskets, as it makes them much easier to clean off next time.

...Cotten
PS: Irregularities like tool mark are good. They hold the gasket.
Irregularities like the common warpage of flatties over the intake port are more than I would like to trust to a band-aid.

Oh yeah, aluminum OHVs suffer from that too!
Knucks not so much.

PPS! Heat-Paint upon vintage productions of asbestos or cardboard-like head gaskets should be worth the gamble.
Please do NOT use it upon modern adhesive-impregnated gaskets such as from my preferred supplier, JAMES.

That means manifold gaskets, too.

[duffeycycles]

From Chris:The MoCo always used copper head gaskets until the war time restrictions on copper during WWII came into effect. It was at that time that they started using asbestos gaskets. Copper gaskets can be annealed and reused. A thin later of aluminum spray paint makes a great sealer.
The 1940 parts books show11-36,cylinder head gasket for cast iron head 45" 1936-1940
11-39 for 1939 WLDD & 1940 WLD, aluminum heads
The asbestos/composite gasket was for aluminum head 45" models, starting with the first 45" aluminum head models
11-39 does not appear in the '39 book so maybe problems appeared in '39 so they made the asbestos then
No mention of different gaskets for ULH UH models

[T. Cotten]

Copper for cast-iron, Folks,..

And composite for aluminum for all marques was the way I was raised.
(Too many mentors to remember.)

So that explains my original question, as we are talking Knuckles.
Were OEM iron-head Sportsters' copper?
(Gotta ask, because they were all trashed long before they reached my benches.)

....Cotten
PS: I preferred composite no matter what. Cost, sealability, and insulation seems to make most sense.