Is it a power surge or an OD surge? The former would only alter revs with a
change in speed, the later would alter the revs for the same speed.
As another lister has said a problem in the area of vacuum or centrifugal
advance could cause a power surge, it did happen, which is why the factory
fitted the Transmission Controlled Spark Advance switch and solenoid, but
not until late 76.
Whilst experimenting with the OD a while ago I was putting various
resistances in series and reached a point where at about 25 ohms the OD
gently cut in and out on its own. Below that it stayed in and above that it
didn't go in at all. However if you disconnected the yellow wire and it was
still happening it must be making a resistance short with another wire
carrying 12v between that point and the OD, which could be the green to the
reverse light switch.
PaulH.
----- Original Message -----
From: "David Councill" <dcouncil@imt.net>
To: <mgs@Autox.Team.Net>
Sent: Wednesday, September 29, 2004 6:54 PM
Subject: surge-o-matic
> A few weeks ago, I was cruising down hill on the way to work, downshifted
> my OD, and right after that, the car started surging, as if the overdrive
> was engaging and disengaging while I was in third gear. Didn't do it in
> second. I thought maybe the switch was not cutting off power, making the
> connection go on and off and back on. So I unplugged the connection of the
> OD to the wiring harness, figuring I'd deal with the switch later. That
> appeared to take care of the problem.
>
> But then yesterday, same place and roughly same time in the morning, the
> surge comes back in third gear...
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