Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Head Gaskets & Generator

Head Gaskets & Generator

Post Thu Jul 12, 2018 8:40 am

Posts: 8
OK, Couple of questions;

1. Which head gaskets are best, blue paper types or the copper type
2. If copper type, do they need to be annealed before fitting
3. I don't have anything to anneal them with, can I put them in the oven? do they have to be cherry red?
4. If blue paper type, does anyone use addition gasket glue?

I have the Cycle Electric 12v generator fitted to me UL, on a recent trip one the securing bolts sheared;

a. Has anyone else suffered this problem?
b. If so what caused it and how did you fix it?

Thanks in advance for any replies.
1941 UL

Post Thu Jul 12, 2018 4:15 pm

Posts: 3488
Location: Central Illinois, USA
Welcome Barnsyuk!

Aluminum heads do best with composite gaskets.
Cast iron heads can accept copper gaskets, if the gaskets are quality.

New copper gaskets should already be annealed (softened).
The common recipe for a used gasket (in an emergency) is to heat it cherry red for a while, but I never bothered,.. because I prefer composite, by my experiences.

I would really avoid the embossed copper productions from India.

On to your CE, (which should be a great unit, but terminally ugly if you got the endmount regulator...),
Its case was tapped for 5/16"-24 bolts through the camcover and case.
Often simple ¼"-24 Helicoils are directly installed to convert for original bolts. Unfortunately many many more motor cases were hogged out oversize.
If it was not drilled out squarely, certainly issues arise.

Please disassemble and inspect quite closely:
Are the securing bolts 1/4" or 5/16"?
Are their any cushioning shims at all beneath the generator, resting upon the motorcase?


Post Thu Jul 12, 2018 6:09 pm

Posts: 100
Why do aluminum heads do best with composite gaskets?

Post Thu Jul 12, 2018 7:47 pm

Posts: 1731
Location: Interlaken, NY USA

I've had good luck using copper with aluminum heads and Iron cylinders over the years. I don't know if mine are the indian ones or not. Had them 6 or 7 years now. In truth, I don't bother to anneal them, just keep reusing them. Apparently the 16-18 horsepower developed within the cylinder isn''t enough to force it's way out :D
There was a lengthy discussion on the merits and appropriate usage on the different styles of gasket awhile back, and I don't remember there being any definitive resolution to the question. Just opinions.

Post Fri Jul 13, 2018 7:52 am

Posts: 3488
Location: Central Illinois, USA
LarryP wrote:
Why do aluminum heads do best with composite gaskets?
Aluminum is soft, Larry!

I have seen impressions of copper gaskets beaten into the head.


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