I went through a similar thing (there was a thread a while back,
"gutless under 2500 rpm" - that was me), and I solved it by swapping in
a different dizzy. What really was the problem was too much ignition
advance/wrong advance curve. This also was in combination with carb
settings. I've got twin SU's on my 1500, but the principles are the
same.
First, a couple of questions. What dizzy are you using? I'm unfamiliar
with the Crane system, but you need to be reasonably sure the ignition
advance curve in the dizzy will work with the engine.
Second, with respect to the timing, what happens when you set timing
less than 13 degrees? Does the idle speed go down? You may try retarding
the timing a bit and turning up the idle speed to compensate. With an
agressive cam, you'll never get a stock idle. I'm idling about 1200 rpm
with my headlights on, and it sounds really lumpy anything under that.
But you may already be up on the mechanical advance curve. I set my
timing at max advance. This requires an adjustable timing light, so if
you don't have one beg buy borrow or steal one. Rev the motor up to
3500-4000 rpm. I set mine to 30-32 degreees max for a 1500.
Third, do you have a vacuum advance connected? If so, disconnect it and
plug the hose, and see how that works. I've had mine disconnected and
it's been running fine.
"vrrrmwoooorrrrrr" sounds like you may actually be lean under load, and
the engine isn't getting enough fuel to go. In the case of my SU's
stiffer dashpot springs helped a lot. I'm not sure how that translates
to Weber adjustments, but maybe someone can translate from SU to Weber
;)
Hope this helps. Hang in there, you'll get through it.
-=Chris
<-----Original Message----->
From Dbcooper292 at aol.com
Sent: 7/6/2004 9:46:26 PM
To: spridgets@autox.team.net
Subject: Re: car runs but need help -update and plea
Help! I've done a lot of what I can think of but can't make my car run
right. It starts and idles nicely (sounds real cammy under 1K rpm but
smooths out
fine at 1,100), but dies under a load. It will drive around on my
perfect
garage floor and drive out down the 1% grade but won't back (or drive)
back up
it. It doesn't pop or bang or violently die, it just goes
vrrrmwoooorrrrrr and
dies down. If you push in the clutch it's likely to return to idle. It
just
acts like it lacks the necessary (12) horsepower to do the job. Here are
some
facts:
1500 motor, weber downdraft, fuel regulator, crane 700, ATP fast street
cam,
manual choke, header, 1 3/4 exhaust. Breather tube from valve cover into
air
cleaner, in case that matters.
I have tried:
aligning the crane system. I haven't done the hole in the dist. cap
thing
b/c my dizzy seems too small for this (the cap in the illustration must
be for a
25 cylinder airplane or something) but I have checked it with the cap
off and
if it's off it's not by much. Seems right on to me.
Played with the timing. It seems best around 13-15 btdc. Will actually
idle
nicer around 20 btdc but starts hard like you'd expect, etc.
Adjusted the Weber per the tech tips.
All these things seem to make slight differences but not much. I guess
I'm
wondering if my jet is too rich b/c it seems I can reduce the idle to
ungodly
low speeds and still get away with closing the idle mixture screw
completely
without the engine changing much, but I'd appreciate hearing the list's
thoughts
before I go bodging around in the carb.
Help a brother out? I'm sooooooooo close to driving this (registered)
car
after 2 1/2 years. If you help me I'll send you anything left over from
making
one car out of two that you want. (heaters? I've got two! Want a front
fender? trunklid? How about some really ratty seats?)
Thanks!
Mark M.
.
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