valve seat depth what isoptimum?

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recentjester
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valve seat depth what isoptimum?

#1

Post by recentjester »

I just bought some heads, (1950) they are brass and look like they have meat left in them. On page 75 of the old pan manual they show a gauge u could use to check the amount the valve stem is actually sticking up. because of different valve guides, (Rowe, Manley, after market) this distance is not really in the book. In order to have the valves opening at the absolute correct moment in the stroke of the engine how do to u determine this? This is my primary concern in getting these valve seats cut and lapped. Would valves that are seated to deeply (sunken valve seats) make starting tough? Jester
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Re: valve seat depth what isoptimum?

#2

Post by fourthgear »

There are those here that will know what the min/max measurements are , but if you want to take the seats (if they are OEM bronze)back to spec's. Head Hog builds them back up to spec's .

Its not cheap , but worth it if you want to start over with the heads to spec. My 65 heads came out perfect.
1950Panhead
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Re: valve seat depth what isoptimum?

#3

Post by 1950Panhead »

Insert a valve in a head with no seat wear, use a depth micrometer to measure distance to center of valve face. Insert same valve in any other head, repeat measurement. The difference in micrometer readings is an approximation of valve seat wear. Use trig if you want an exact measurement (micrometer and valve stem are on different axis).
Jerry
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Re: valve seat depth what isoptimum?

#4

Post by George Greer »

fourthgear wrote: Head Hog builds them back up to spec's . Its not cheap , but worth it if you want to start over with the heads to spec. My 65 heads came out perfect.
Not all of the heads with original seats still left can be repaired by him. I know, he has a set of mine and that's what he told me about them.
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Re: valve seat depth what isoptimum?

#5

Post by Cotten »

Jester!

Kitabel would best tell you if there is an optimum depth for flow, etc.,
But most of us are concerned with either Factory zero, or making do with what we have.

When installing a fresh seat, the valve stem protrusion should be the minimum as shown in the Service Manual chart.
(I found that seats as little as .010" proud of minimum can cause valves to hit each other with a mild performance cam.)

"Making do" must often use tricks tailored to each individual valve assembly.
But oversized valves must have their seats cut to the minimum stem protrusion as well.

Quality replacement guides have a shoulder of similar height to OEM.
Inspect, however, for previous free-travel cutting, and whether there is a gasket in place.

Good luck!

....Cotten
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