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5/10/17 10:45am - Original Message: 'Starts up OK, but stalls'
Freds78corvette
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Joined: 2/20/2017
Posts: 3
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.
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5/11/17 1:39am - Reply: 'Re: Starts up OK, but stalls'
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

Joined: 7/9/2003
Posts: 376
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

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5/11/17 9:13am - Reply: 'Re: Starts up OK, but stalls'
Freds78corvette
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Joined: 2/20/2017
Posts: 3
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.
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5/11/17 1:41pm - Reply: 'Re: Starts up OK, but stalls'
stingrayjim jr Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
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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5/11/17 1:45pm - Reply: 'Re: Starts up OK, but stalls'
johnu
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Eagan, MN - USA

Vette(s):
1981 Corvette Two-Tone Claret color, 4 spd, C7 Vert

Joined: 5/23/2007
Posts: 504
A new engine with a flat tappet cam should high idle at 2,000 rpms for a bit, right?

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      Only 23 years together
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5/12/17 12:10am - Reply: 'Re: Starts up OK, but stalls'
stingrayjim jr Lifetime Member
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SHELBYVILLE, TN - USA

Vette(s):
1976 L48 auto

1978 L82 4speed

1994 LT1 6speed

Joined: 7/5/2002
Posts: 3934
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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5/12/17 8:46pm - Reply: 'Re: Starts up OK, but stalls'
gtr1999
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Wallingford, CT - USA

Vette(s):
1969 350 4 spd drop top 1972 350 auto coupe

Joined: 5/2/2016
Posts: 53
There is not a lot to go on so a couple of questions.
 
Was the cam correctly broken in at first start up? I read the post and assumed the engine was broken in? There are a couple of methods of breaking in an engine but I agree if the cam is flat tappet and broken in for 20-30 minutes over 2k the rings will be seated at the same time.
 
So if the engine is broken in you may just have to make some adjustments. Are you familiar with old school tune ups? What carb are you running? Possibly vacuum leak?
 
Depending on the cam specs you could be in the 800 rpm range, choke open, eng warm in neutral.
 
When I drove my 69 as a DD I setup the engine for torque, not a high RPM setup. The engine idled smooth at 750 rpm and drove fine. My 72 with base engine cam was smooth at 600 in drive. When I installed a 260 cam it is now a little choppy but nothing crazy.
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5/12/17 11:31pm - Reply: 'Re: Starts up OK, but stalls'
F4Gary Gold Member
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Grapevine, TX - USA

Vette(s):
1972 LT-1 convertible with factory air.

Joined: 8/26/2006
Posts: 862
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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5/13/17 8:31am - Reply: 'Re: Starts up OK, but stalls'
nosal1 Gold Member
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Dunedin, FL - USA

Vette(s):
1980 Corvette Torch Red with Gold metallic 370HP/350 CU.IN.Turbo 350 w/shift kit.Originally CA.Car with 305 CU.IN.

Joined: 3/21/2006
Posts: 224

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



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5/13/17 10:11am - Reply: 'Re: Starts up OK, but stalls'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 19449
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. Thumbs Up



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Joel Adams
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