Hello, looking for some advice.  I have a 1978 corvette pace care, new engine rebuild, new edlebrock carb, new starter, new battery.  I can start the car, turns over well.  However, when I take my foot off the gas pedal, the engine stalls.  It seems to me the idle is too low, but I don't know.  Can anyone tell me how to proceed?  Thanks in advance.

Idle should be around 700 rpm when warmed up but should be higher on a cold start. Idle is set in Drive on an automatic. 

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1973 L-82 4 spd

Thanks, it is a manual 4 speed.  Should I tweak the idle screws on the carb?  Or could the issue be in the fuel delivery system?  Really appreciate the advice.

It would be ok to 'tweak' the idle screw, just check you tach, I usually set my idle around 900 or so with a manual transmission in nuetral, someone else here might have a better number to use, but it can always be reset easily... but do make sure the engine is up to temperature. Also check and make sure all your vacuum ports are plugged off.  

|UPDATED|5/11/2017 10:41:45 AM (AZT)|/UPDATED|


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StingrayJim
NCM Lifetime Member #1936

Stingray's '76���������������������������� StingrayJr's '78���������������������������Lil Red '94

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A new engine with a flat tappet cam should high idle at 2,000 rpms for a bit, right?

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just did a quick search and yes, recommended break in procedure is to run 2000 rpm's for about 20 minutes, and if using Moly type rings, they will be basically set after this time too, if using Chrome, then a little more time involved with  drive time with light acceleration and deceleration to seat them in

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StingrayJim
NCM Lifetime Member #1936

Stingray's '76���������������������������� StingrayJr's '78���������������������������Lil Red '94

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There is not a lot to go on so a couple of questions.

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The factory idle for my LT-1 is 900 rpm.
Do you work on your car or does someone else?
I'd set the idle mixture screws at about 1.5 turns and then run the idle set screw in a bit so I can get out of the driver's seat and tweak on it.  Check the timing, vacuum, and idle mixture.  Then back her down  a bit and do it again. Work your way down to 900 rpm.
You may have a vacuum leak.

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Good Morning I have a few questions!! Is this a freshly built engine and if so have you seasoned the cam(2000 rpm for 20-22 minutes)??Is the Edelbrock carb "brand new out of the box"as they advertise?? It sounds like from your description that the fuel bowl is not at the proper level and the accelerator  pump is not pushing fuel to the cylinders..  Try turning the primary screws in and bottom out them and then back them out 2 and a half turns.Mark the screws so you don't lose count.If this does not help then it is possible that the floats need to be adjusted.It is not unheard of that the floats were not set right in the factory.It is not the "good ole days when you could take a new Edelbrock out of the box and run with it without a problem"..Their advertisement not mine..I have several Edelbrocks and Carters and all but the Carters had to be rebuilt to run..Good luck and I wish you success..nosal1   

Sal C

As others have mentioned, more info on the engine is needed. IF the cam has already been broken in, then it sounds like you simply need to adjust the idle speed of the carb, which is fairly simple. If this is a NEW engine build that you are attempting to start, do NOT continue to start it and let it die...that will destroy the cam/lifters quick! If the engine has a roller cam/lifters, then it's not such an issue, but with a flat tappet cam, you MUST start it and let it run at 2000-2200 rpms for at least 20 minutes to allow the cam & lifters to "break in". Attempting to allow the engine to idle at a low speed will not allow the cam/lifters to be lubricated properly, and thus they will wear rapidly.

On a new engine start, adjust the idle speed adjustment screw IN(tighten) at least 4-5 turns to raise the idle speed, then start the engine, and adjust the idle to at least 2000-2200 rpms, and just let it idle. Make SURE there is coolant in the system, and check for any leaks while this is happening. After the cam break-in period, adjust the idle speed down slowly until the engine will idle properly. From thee, you can make any final carb/timing adjustments needed.

I e-mailed you a PDF on the adjustments for the Edlebrock carb, and it explains how to fine tune it.



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Joel Adams
C3VR Lifetime Member #56    
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