Andrew Lundgren's question below about more tappet noise raises a question.
Too many years ago to relate, I drag raced a 6-cylinder Chevy (Stovebolt
Six). It was quick for the time & held the class record for a while. My
best 1/4 mile time was 16.4. Slow now, but...
One of the modifications I made when running Altered class was to run a cam
from the automatic ("Powerslide" to those who remember.) trans engine as it
was the only difference between that & the stick engine and it was rated at
another 10 h.p. (125 vs 115). However, I ran it with solid lifters, not the
a/t engine's hydraulic lifters. Someone told me that because the hydraulic
lifter cam didn't have "take-up ramps" designed into the cam profile, it was
necessary to run REALLY small clearances. If my failing memory is right, I
set exhaust at something like .005 & the intake at .003.
Did it work? You betcha! The engine idled as if it had a 3/4 race cam.
And, ran like a scalded cat. My shift point was 6,000 rpm's. Wish I could
have seen the look on the face of the guy driving the '61 Fuelie Vette when
I smoked him off the line in Time Trials. Of course when he passed me he
was going about twice as fast as I was.
But, here's the question - is there any advantage to running closer
clearances on our MGB's for racing. Perhaps .010? It will increase valve
opening and duration. But, will it cause problems? I did set gaps at .013
last race. Got rid of ALL of the valve clatter. But, since I didn't have
anyone timing me, I never had the opportunity to try the changes for effect
on times.
Any camshaft engineers out there?????
Norm Sippel
'66 MGB - New paint, and now new top, although it still doesn't fit quite
right.
Subject: Questions about non-crossflow Aluminum head
"Since I know now that there are a few other listers with the standard AL
head I will ask a few nagging questions:
My AL head seems to tap much louder than the iron one did.
This has me a bit worried, but as I have never heard another I don't know
what is good/bad. I am also running a mild performance cam with my vales
gapped at .18 rather than the stock .15."
Thanks!
Andrew
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