Potential valve problem

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Potential valve problem

Unread post by socalcorvair63 » Sat Sep 16, 2017 1:10 am

I'm having a problem with my 1963 monza coupe. I noticed a while back that there was some popping in the exhaust that sounded like a potential valve issue, but thought nothing of it because the motor had good compression (lowest was 130 psi in cylinder 1) and it ran pretty well, despite having some mechanical noise that I assumed was a collapsed lifter or loose rocker arms. While tuning the carbs, I noticed that the passenger side bank was pulling a few pounds more vaccum pressure from the right, and no adjustment of the idle mixture or throttle plate screws could change that, and I had an intermittent problem with the passenger side bank not firing which was temporarily alleviated by cleaning the carb on that side. I then adjusted the valves on the car on the drivers side and passengers side, and am having a similar problem to the one I had before. The drivers side bank runs fine, but the p/s bank is pretty much cold. If you take off the linkage on the p/s carb and open the throttle on that carb only, it slowly revs while "coughing" and putting out a decent bit of smoke. I may pull the head and inspect for burnt or damaged valves, but i'm not sure if pulling just one head and replacing whatever part is worn is a good idea on a motor this old. it has 74,000 miles on it as well, and from what i've been told, that's about the average lifespan of these motors. I also noticed that there were solid pieces of metal in the pan when I replaced the oil pan seal that could have potentially came from the cam gear, so that also makes it harder to pinpoint the problem. If anyone has any advice on what route I should take in solving this problem, feel free to chime in.

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Re: Potential valve problem

Unread post by funvairs » Sat Sep 16, 2017 6:17 am

do you have a vacuum gauge? A vacuum gauge can be used to troubleshoot a variety of issues This link shows what different gauge readings indicate.
Chris Brown

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Re: Potential valve problem

Unread post by terribleted » Sat Sep 16, 2017 11:44 am

Sounds like a carburation issue. Are you sure the carbs are clean and adjusted properly. You say P/S is cold this would indicate that the P/S carb is not working thru the idle circuits. This issue is somewhat common particularly it the car has or does sit a lot or if the fuel system has not been completely purged of debris and the carbs rebuilt. Sometimes this type issue can be cleared by revving the engine and slapping your hand over the top of the offending carb blocking its airflow momentarily a number of times which can suck through or dislodge a blockage.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.

Located in Snellville, Georgia

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