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Discussion Starter #1
I'm happy to be a garage mechanic in training. I REALLY enjoy working on my vette. I've often gotta learn everything, as you prob do as well, on your own. I've been fighting a rough "in gear idle" for the last few months. Just thought I'd let anyone know what the solution was. I've got a stock '79 L82...no mods what so ever.

First the problem. The engine would start up and idle in park really nice. If you put it in gear right away no problems either.... but after the engine got up to running temp the "in gear" idle would chug down below 500 and often stall. Not all the time...most of the time.

I had a race mechanic do some work on the steering and brakes and I mentioned the problem to him. After he looked at the carb a bit and found it to be as it should he suggested I check three other things at home.

The first was to maybe switch back to the stock spark plugs...I had put in some double platium plugs that he thought may have been causing the engine to miss because double platium plugs are "too hot" according to him for older engines.

The second was to check the distributor cap for carbon trails...a sign of arcing that would cause the engine to stumble in gear as well.

The third was to check the rocker arm lash. He thought I may have gotten the lash too tight over the winter when I was trying to get rid of some rocker arm rattle.

After I checked the above two it turns out the third one was the problem. I went back are re-did all the rockers and now the engine idles really nice in gear.

Just an FYI to check. I've seen this "in gear idle" question posted before and this may be your problem as well. Many people think it's a carb problem right away, as I did, and it wasn't the case at all in the end.:cheers:

As mentioned before, I could hear one, or several, rockers rattling when I first got the vette last summer. The rockers would only rattle after the engine was good and warmed up. The engine would also diesel on shut off too every so often. After I tightned up the rockers the dieseling went away...but the bad "in gear" idle then showed up....thus I've learned the valve lash setting is to be set very carefully...too loose and you may diesel...too tight and you may have idle problems.

Just food for thought....
 

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Are you using hydraulic lifters? If so, how did you adjust them? I am having an issue with mine. I adjusted them when I rebuilt the engine and the lifters were new (dry). I'm having noise and idle problems now and cannot adjust them with the engine running because the Comp Magnum roller tip rockers won't allow a wrench on the nut while the engine is running.:bang God bless, Sensei
 

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Discussion Starter #3
sensei said:
Are you using hydraulic lifters? If so, how did you adjust them? I am having an issue with mine. I adjusted them when I rebuilt the engine and the lifters were new (dry). I'm having noise and idle problems now and cannot adjust them with the engine running because the Comp Magnum roller tip rockers won't allow a wrench on the nut while the engine is running.:bang God bless, Sensei
Yea the stock engine has hydraulic lifters.....

I used this procedure after I warmed up the engine for about 15 minutes:
http://www.vettefinders.com/index.cfm/fuseaction/Vette101Story/ID/17

You gotta work quick though because as the engine cools all the metals begin to cool and contract back down again. Plan your attack and have all your tools ready to go. Take off as many of the accesories as possible to get the valves off before you warm the engine.

In short, I marked the harmonic balancer at the 0, 90, 180, and 270 degree locations using a tape measure...for my stock '79 L82 that was every 6.25 inches around the flywheel. That way, every 90 degrees, I could just go in the firing order and adjust both the exhaust and intake at the same time on that sequence cylinder. Two rotations and your done.

The rest is in website above....:thumbsup:
 
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