Panhead Valve Seats

I've noticed on the earlier (1948, '49) cylinder heads, when the factory cast the aluminum head itself, there is not much material under the valve seat area.  The kept the port open as possible(maybe for air flow?) If you machine(bore) out the original valve seat for replacement, you don't have adequate "support" for the new steel seat on some of these heads . . .
The head above appears to have adequate support needed (without welding up the head, which can cause warping, cracks, etc.) which is a good thing.
These steel seats are an improvement.  All seats require a heavy press fitment.  If seat fitment is not tight enough, the head expands(from the heat) and the seat falls out.  I have the original bronze seats still in my panheads, stock from the factory.  Hopefully I can get a few more miles on them before they need replacement?  Old Harleys just keep on runnin' - 'til they don't !

5 comments:

  1. BradTuesday, September 26, 2017

    When I had my ironhead heads done he said my seats were getting a little low and time for new seat inserts. The guy, that he knew, with the equipment to do this, wanted 800$ per head to put in new seats. My bike isn't a race bike, so I left it alone (except for new valves and dressing the seats). Now, if I just had a million dollars to spend on tooling & equipment...

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  2. NootWednesday, September 27, 2017

    Just use larger valves and move the seat out. Some people get carried away grinding seats 'til there ain't no meat left !

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  3. BradSaturday, September 30, 2017

    For sure. The motor only has about 20k on it. I had the valves done in Houston back in the 70's and once more. I've seen people (youtube) put grinding compound on the valves and spin away like they expect to do a full on valve job with that. All they end up doing is grinding a step into the valve. A couple of times around to check the seat..done.

    When I re-did my 175 head I called a shop in the big O and he wanted 200$. I said no, no...it's apart and I'll put it back together....just clean the seats (4) up with a stone, the valves are brand new. Yup, 200$. I won't say how I did it...you'd hate me..but they looked good, they sealed and the bike runs great.

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  4. NootThursday, October 05, 2017

    I love your comments Dave. Seriously, you've done it and been there, and I like that 'cause that's how it is. Thanks Dave. Have a good week, and make some time to go for a ride !

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  5. JayTuesday, October 10, 2017

    I spoke with the guys over at branch engineering in Signal Hill california. They in no uncertain terms told me that when you replace the valve seats on panheads you need to leave a little "cushion" of the original bronze seat. Otherwise they will eventualy just fall out. If you take them heads that have had the seats changed the "wrong way" they wont even touch them.

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