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High idle and misses

To: <>
Subject: High idle and misses
From: "Alex Avery" <>
Date: Fri, 13 Aug 2004 15:31:28 -0400
Hi guys, hope all is well with all. I've got a tuning problem and am hoping
for some leads.


As you may recall, last year we had to replace the head on our U20 after the
cam snapped in half. The head had previously been milled and was down 1/10th
of an inch - too much. So we got a new head (thanks Dean!), new cam, timing
set, etc. 


After she was back on the road early this summer, I couldn't get the carbs
set right for smooth running nor could I get the idle down below 1,100 rpm
without her dying. So I sent the carbs off to Apple Hydraulics on Long
Island for a rebuild. They really needed it BAD. Got those back and back on
the car. But I still couldn't get her running right. So I convinced my
father-in-law's mechanic, Al (who does only very high end cars, from early
1900 classics - my father-in-law has a '35 Packard convertible - to Allards
and Ferraris and who has owned many a MG, etc), to take a look and balance
and tune the carbs.


He found a few other issues, such as the exhaust manifold had several
cracks. So Dean sent us a sweet header, tune up kit (points, condenser,
etc.) cap, rotor, etc. After getting all that set, he says he still can't
get the idle down to the 600 rpm stated by the FSM. He says, "I think that
when your other guy put the new head, etc. on the car, he inadvertently got
the timing chain on one tooth off. The only way I can get her to run
semi-smooth is with the timing set to 15-20 degrees advanced. The timing
isn't even close to the marks. We need to make sure the valve timing was set
properly before we go any futher."


So I take the car over to Louis, my everyday guy and who did all the head
replacing and such, and He says, "BS!, but to prove it to you, I'll move it
a tooth either way and see if we can't get her to run better." That didn't
do anything but make it worse.


The car runs ok, but not great. The idle won't go any lower without it
stumbling and running rough. Semi-smooth at 1100, and pretty smooth at 1600.
But we should be able to get her down to 600 no problem. Plus the power is
off on throttle - way off.


I don't have any vacuum leaks, no head or manifold leaks. What should I be
looking to next to find out why she's missing and the idle won't come down.
I don't think Louis really knows this kind of car well, but I don't think he
screwed the cam timing by setting her off a tooth. Al now wonders if it's a
coil or something in the ignition.


What's the easiest way to ensure my valve timing is correct? What other
things should I be looking at? I just want this car to run right and strong
and there shouldn't be any reason why we cant given all the new parts and




Alex Avery

Director of Research

Center for Global Food Issues, Hudson Institute

PO Box 202, Churchville, VA 24421

(540) 337-6354, or -6387

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