Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties UL valve seat width

UL valve seat width

Post Thu Feb 15, 2007 12:31 am

Posts: 42
Location: Finland
What is the proper valve seat width in big flat cylinders?

I have read all my books and also done some search here...
And all I found was confligting information.

original width information found was 0.15625" 45deg angle(pretty wide)
and Palmer book tells to narrow to 0.0625" (suprisingly narrow)

basic aircooled OHV engine seats are around 0.09"..but this is flathead.

Any opinions why this much difference in information? Or is this only
result of 60 year development and people still can't agree?

My old seats seems to be on narrow side,,but needs resurfasing.

Post Thu Feb 15, 2007 7:42 am
panic

Last edited by panic on Fri Feb 23, 2007 5:24 pm, edited 1 time in total.

Post Thu Feb 15, 2007 11:25 am

Posts: 42
Location: Finland
Thanks for fast reply/correction. Exhaust is critical for contact but so is the seat pressure.
In intake I consider 0.08" - 0.09" enough for width.

Normal street use is what they get.

Post Thu Feb 15, 2007 3:45 pm
panic

Last edited by panic on Fri Feb 23, 2007 5:24 pm, edited 1 time in total.


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