C-85 Rocker Arms

[flyguy]

What is with the off-center rocker to valve tip interface/position on the exhaust valve on my C-85?

First--the Continental manual lists different part numbers for the exhaust and intake rocker. Then I find the only part number available from suppliers is the number listed by the manual as the exhaust rocker, but going thru 10 rockers from the local engine shop I find they all center fine on the intake and off-center on the exhaust.

This is a replacement cylinder from the shop, but another original cylinder on the engine I checked has the indentical situation. Exhaust rocker looks same as the intake and is offset on the valve stem face. The wear pattern on the original rockers indicate the same wear pattern for the cylinder replaced.

This is a little flaky, even for an engine designed in the 1930's.

Any of you engine guys have any input for me on this bit of weirdness?

Darryl

[N96337]

Re: C-85 Rocker Arms

The main reason for the different part numbers was the exhaust rocker has a drilled oil passage for cooling. Just try an intake rocker on an exhaust valve... it doesn't last long without that oil spray. They just decided it would be easier on the mfg as well as the shops if there was just one rocker, so now both intake and exhaust have the oil passage. As far as offset, I don't remember it being significant enough to be very noticeable...but it's been a few years since I've done much small Cont. work.
John

[flyguy]

Re: C-85 Rocker Arms

Thanks John.
That certainly makes sense. I suspect that there is something going on there with the location of the centerline of the exhaust valve on the C-85. Just an interesting little item that I am going to check on a bit. I think I will take a look at the alignment of the exhaust rocker on a 65 jug as it uses the same rocker. Interesting.
Darryl