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RE: Rev limiter revisited-Pertronix

To: fot@autox.team.net
Subject: RE: Rev limiter revisited-Pertronix
From: Bill Babcock <BillB@bnj.com>
Date: Wed, 8 Sep 2004 22:49:44 -0700
 It's kind of Ironic--when the car was running lousy I got two second place
finishes. Once we got the miss fixed, Cameron Healey's Pooper was back in
action and I got relegated to two third place finishes. 
 
Well there's lots of things to check--I spent all Saturday and Sunday
chasing stuff. I'd start with spark. Look for the kind of scatter we've been
talking about--where your timing mark starts jumping all over at higher RPM.
It should be rock solid if everything is OK. Check your distributor over
really carefully--look for shake in the points cam, a bad cap (carbon tracks
or other signs that sparks are going strange places, sticky or cracked rotor
contact (the spring-loaded carbon brush in the center) , marginal wires,
etc. Check your voltage by gapping your plugs tight--like .010" just to see
if the problem goes away--or gap them wide, like .050" to see if it gets
worse. 
 
I don't remember what carbs you are running, but start by ensuring you have
the right fuel pressure. I've seen a lot of cars run out of steam on the
straights because the regulator was set too low. If you have some place that
you can do a plug chop ( a long hill out in the country is great) warm up
the motor, stick in some brand new plugs, go full throttle up the hill and
cut off the ignition. Read the plugs. The good guys like Bobby Strahlman can
tell you your Momma's maiden name by the look of the plugs. Use a little
flashlight to look at the insulator at the base--should be white with a tiny
hint of brown. If you see soot way down there you're too rich. If it looks
blistery white you're too lean. Can't tell that much from the insulator tip.
Look closely at the center electrode to see if there's a little splash mark
in the metal--if there is your voltage is probably ok. 
 
Somehow, people don't seem to read plugs as much as they used to. Maybe it's
my motorcycle roots, but I still spend a lot of time doing plug chops and
staring at plugs. It's a good way to zoom in on the kind of problem you're
talking about. Of course it wasn't worth squat last weekend.
 
The late, lamented Gordon Jennings was one of my Gurus in the 70's, this
article by him on reading plugs is typical of his stuff--very useful, even
though it's about motorcycle plugs. http://www.strappe.com/plugs.html
<http://www.strappe.com/plugs.html>   . I sure miss the days when Cook
Nielsen was the editor of Cycle Magazine and Gordon was the technical dude.
They did some wild stuff. 
 
There's a comprehensive set of pictures at
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html
<http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html>   but as in all
such pictures, they show the tip, not the insulator base, which is where the
real guys read them. 
 
1:41 is pretty respectable. When you hit 1:38 you'll be in the top five most
days. Little increments. But I'll tell you a secret that will drop two
seconds off your time--turn 4 isn't a turn, it's just an extension of the
short straight from the chicane. Everyone brakes and downshifts there. Try
not downshifting and braking less. Then try just tapping your brake and
getting right back on the gas. Then try not lifting your foot. Remember that
the line through a smooth corner is an absolute thing. If you can position
your car anywhere you want in a corner, then you aren't going fast enough.
There's three places to gain big at PIR--the exit of 12, the entrance of 4,
and the exit of 5. Twelve is your classic, slow in, fast out corner onto a
straight. Take it late, smooth, drift out to the wall, and Bob's your uncle.
Five is where everyone screws up by taking the apex too early. Go very wide,
very late, and you'll see the corner open up in front of you, a near
straight line through 5A to the back straight. If 5A feels like a corner
then you apexed too early in 5. Twelve and 12A can be negotiated flat out in
Peyote, and probably your car too. I don't do it every lap, I do a little
tap for good luck, but it's not really braking, and I shouldn't be doing it.
 
Anyway, all that might not work for you, but I figure there's five seconds
easily in the paragraph above. I expect 1:36 from you next time.

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