I had alot of problems with my six after I had the head worked on (problem
eventually turned out to be a fouled carb from not purging gas line before
re-attaching carb).
I installed a manifold vacuum gauge under my dash and swear by it now- it's
really helped me get a good tune on the 235 and diagnose a wide range of
settings/problems (I used mine to check efficeiency of valve lash, timing,
lean, spark advance, ignition, etc. before getting to the root of trouble-
'needed to get done anyways). Anyways, here's some good web resources on
diagnosing w/ vacuum gauges.
Reading your vacuum gauge (xlent chart- courtesy of suburban owners group)
http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm
Motor Age Magazine: Driveability Diagnosis
http://www.motorage.com/edindex/069740.htm
Troubleshooting with a Vacuum gauge
http://users.uniserve.ca/~chuckj/vacugage.html
An Essential Part Of Today's Driveability Work
http://www.serviceinsights.com/main/tech/techarcv/0598cap.htm
>
>Date: Mon, 24 May 1999 18:29:32 PDT
>From: "dave p" <my51truck@hotmail.com>
>Subject: [oletrucks] non-truck ??
>
>I have a chevy 350 in my 67 nova and it is running TERRIBLE. <missing,
>sputtering, and even an occasional backfire. I set my timing at 8 before
>TDC, dwell at 30, and adjusted the carb (600 holley). It helped for a day or
>two, then it was even worse. I checked my timing again, days later, and it
>was somewhere near 18-20. I took a vacuum reading and it was steady around
>12, down from 17-18.
>
>With these symptoms what do I need to repair, adjust, or replace. I am
>thinking it may be the timing chain. If it is, what is the worse that can
>happen if I continue driving it. If it breaks, will my valves hit the
>pistons. I am asking you knowledgable folks before giving up and going to a
>shop (something I hate doing)
>
>Thanks,
>
>Dave P
>51 half ton
>
>
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