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1934 Indian 4 valve seats

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Post Mon Aug 20, 2001 4:35 am

Posts: 607
Location: Menomonie, Wisconsin, USA
I am getting to the top end of the motor on my 1934 and was wondering if anybody has ever put exhaust seats in a pocket valve motor cylinder - preferably an early Indian 4 cylinder.

I am somewhat of a machinest but would like some outside information such as how much press fit. What seat might work etc.

If somebody is tooled up to do this, I would not mind farming it out either.

Thanks Jerry

Post Mon Aug 20, 2001 7:44 am

Posts: 1319
Location: State College, Pa.
K.O.LEE has a great catalog to select seats from. You'll have to figure what seats you'll need tho. 605-225-5820 (1988 catalog)
They should offer the interference fit too.


Post Mon Aug 20, 2001 2:05 pm

Posts: 3010
Location: Central Illinois, USA
The only 4our I have played with was a 438, but I assume yours also has the intakes in the "heads", and the exhausts in the castiron "cylinders"??

I believe the exhausts were seated directly upon the matrix iron, and installing a seat insert would merely require cutting an appropriate counterbore. Soft castiron seats need only a couple of thousandths interference (.002"), since they will have the same expansion coefficient as the cylinder. Hardened inserts(necessary?) would require slightly more (.0025"-.003"), as they tend to shrink if overheated.

"Clinching", or rolling the edge of the counterbore over to retain the seat insert is always adviseable.

The decisions you must make are:

Are the seats really that sunken as to need replacement?
Will the machine see such service as to require hardened seats?

Availabiltiy of seats specifically for this application are probably available from Max Bubeck or Dennis Young, but they are most likely to be a Martin-Wells offering for a modern vehicle that has been cut to size. With H-D's, it is very common to custom-cut nearly every seat OD different, in order to save matrix for the next installation. K.O.Lee even offers un-finished blanks for this reason. And lathe-cutting the OD and depth of the insert AFTER cutting the appropriate counterbore insures a proper fit, as the counterbore is the difficult cut to be accurate with. And an insert is a lot cheaper to scrap than a 4our head or cylinder!

Conducting heat away from a hardened seat is critical. Silver Seal Corp. makes "Seal-Lock", a white goober that not only chemically welds the seat in, but fills the insulating voids. Good stuff.
Or you can let Wilson Plank oven sweat and silver-solder them in!

Post Tue Aug 21, 2001 12:11 am

More about Seal Lock? Where to get? Thanks!

Click here to see my Pages-O-Tech-Stuff

Post Mon Aug 27, 2001 3:04 am

Posts: 3010
Location: Central Illinois, USA
Did I get a direct post out to you on Seal-Lock?
It's made and marketed by the SilverSeal corp, and is the goober used when doing pinning repairs. (Where you drill holes and tap and peen them with overlapping plugs for a stitch effect.)
Naturally all of my addresses are at the shop.

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