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Old 02-04-2012, 08:18 AM
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Engine idles rough

I have a "86" 350 chevy that was rebuilt. The only change was the parts shop gave me a RV cam to install. he said that it would give the motor a little rough idle.
Now heres my problem. It starts up good and once it's warmed up it idles fine, but once it's put in gear (drive) it runs rough. I give it gas and goes down the road fine, once I stop at a stop sign it idle rough. How rough should the car idle? Or is ther other problems.


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Old 02-04-2012, 08:26 AM
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Do you have the cam specs? What is the base spark timing set at?
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Old 02-04-2012, 08:27 AM
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If its the original carburetor, it may just need to have the idle mixture adjusted, or have the idle speed raised. You should have an idle RPM of about 700-800 with it in gear, which means it will idle a little higher in neutral.

If that does not work you need to find out where they set the initial timing, and determine if you have any electronic controls on the timing or carburetor. There were a lot of changes from year to year in these vehicles as emissions controls were phased in, so its important to know exactly what you have. Since you put the year as "86" I assume there may have been changes other than the cam.

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Old 02-04-2012, 08:36 AM
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Somewhat of a rough idle with a RV cam is normal. What worked for me is to set the timing at 36 degrees @ 3000 rpm with the vacuum unplugged from the distributor. Then plug the vacuum in to manifold vacuum. Being an '86, I assume that it has the Q-jet carburetor. You may need to readjust the idle jets, then adjust the idle speed @ 650 to 700 rpm in drive. That is about as good as it's going to get, unless you have other problems that need taken care of. But that is a good starting point. Big Al

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Old 02-04-2012, 05:00 PM
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Engine idles rough

I don't have the cam spec's, but I did take it down and have the timing set by an auto repair shop. They also set the carb, which is a Edelbrock 1406.
Other than the carb and cam it's a stock 350.
Could the hydralic lifters be calipeds or ajusted wrong?
I also checked for vacumm leaks, I didn't find any that I could tell.
Also used eiather spray to detect leaks, but it was normal too.
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