Re: Final drive and high revs...

[Tom Harais <tjhemh@domain.elided>]

Joel:

I've had my 304 to a little over 4000 RPM indicated on the tach without
encountering valve float. But the IH springs are relatively weak and I
would be very much surprised if I could get much more before valve float
begins at which point, there is no more RPMs to be had.

This isn't like overreving another engine where you risk actaully
blowing some part of the valve train. The weak link in the IH is the
valve springs and if you exceed their capabilities, the resulting valve
float will act as a kind of "governor" for engine speed.

Damage from too high of RPM also is related to the load conditions of
the engine at the time that you do it. For instance, it is well known
that my 302 sb chevy in my Z/28 has a factory redline of 6,000 RPM but
you can easily run it to 7,000 RPM in the first three gears while
spinning the tires. However, by 4th gear, and when the tires have enough
bite to really load that engine up, you exceed red line at your own
peril.

A husband of a freind that used to race street stock Honda CRXs in SCCA
races, regulary ran them at 8,000 RPM with no ill effect. Of course,
they use a true overhead cam (no pushrods or other "weighty" parts of a
V-8 valvetrain to fly off) and he kept them perfectly adusted as well.

Tom H.