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Old 02-09-2004, 09:17 PM
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rough engine idle

I am new at this. I have a 1979 Chevy Camaro engine in an 86 chevy pick up. It's been overhauled by a rebuilder. It is a 350, edelbrock performer RPM intake, 670 Street avenger carb, 278 crane cam, Accel super coil, headers, and no emissions. The engine is idling very rough, exhaust smells like gas, has power but I think it should have more. It won't burn out from a stop. I have set the timing and don't know what setting to use(degrees). I checked the fuel level through the sight plugs and I only see fuel on front side not on the rear plug. I tried to adjust it but still no fuel. maybe the float is stuck?

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Old 02-09-2004, 09:38 PM
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I would guess your timing should be around 10o intial.
Sometimes the rear fuel bowl won't fill all the way when the front one is leaking gas.

Go on Holleys website and read their tech section Ialso recommend getting a book by SA designs called "Super Tuning and Modifying Holley Carburetors". Holleys are hard to work with if you only have a limited understanding of them. In my opinion they are the best carbs, but only if you know how to tune them.
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Old 02-09-2004, 10:10 PM
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i'd say 12 to 14 degrees. but it sounds like a carb prob.
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Old 02-10-2004, 05:23 AM
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I'll try that later thanks
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Old 02-10-2004, 06:01 AM
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Re: rough engine idle

Quote:
Originally posted by saenz5
I am new at this. I have a 1979 Chevy Camaro engine in an 86 chevy pick up. It's been overhauled by a rebuilder. It is a 350, edelbrock performer RPM intake, 670 Street avenger carb, 278 crane cam, Accel super coil, headers, and no emissions. The engine is idling very rough, exhaust smells like gas, has power but I think it should have more. It won't burn out from a stop. I have set the timing and don't know what setting to use(degrees). I checked the fuel level through the sight plugs and I only see fuel on front side not on the rear plug. I tried to adjust it but still no fuel. maybe the float is stuck?
Again... dump the holley and go with a q-jet, if the idle is too rich on a q-jet, all ya do is turn the screw on the top, that simple.
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Old 02-10-2004, 09:58 AM
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also that cam is alittle much for that low compression motor
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Old 02-10-2004, 10:32 AM
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Re: Re: rough engine idle

Quote:
Originally posted by 87442lover
Again... dump the holley and go with a q-jet, if the idle is too rich on a q-jet, all ya do is turn the screw on the top, that simple.
Hmmm, been rebuildng Q-jets for over 25 years and have yet to see the magical screw on top.

Sounds to me like the power valve may been leaking.
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Old 02-10-2004, 02:47 PM
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I'm probably going to start a debate here but...set your timing at 38 total mechanical advance all in by 2400-2800. You will need a dial back timing light or a timing tape on the balancer. Hook up your vacuum advance to the manifold port so you have full vacuum at idle. When you do this, notice how the base idle increases. Back the idle off and with the mixture screws set the idle to the highest vacuum reading (you will need a vacuum guage) at about 800 rpm. What this will do is set your idle up properly. What happens with bigger cams and lower compressions engine is that to get the engine to idle you wind up bypassing the idle circuit and running on the main circuit. When hooking the vacuum to a manifold source you compensate for the idle with the increased timing. You back off the idle onto the idle circut. Basiclly you are running to rich,hense the stincky exhaust. Try this and report back. It has worked every time I have done it. You might need a higher stall convertor to make it more responsive but tuning as I've described above will help matters.

Steve
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Old 02-10-2004, 08:45 PM
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I got home too late today so I'll try tomorrrow PM, Thanx for advice.
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Old 03-19-2004, 07:32 AM
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I will be trying this also on my buick v6, due to a similar problem. I'm not running a real big cam, and I'm running an edelbrock carb, but I am having a rough idle problem and although I am not fouling plugs, the exhaust smells a little rich. I am actually running two or three stages lean on the 500 cfm carb, and before rebuilding the motor, I was running rich still (also replaced the computer controlled distributor with a vaccuum advance one which probably helped out a lot). I used the same plugs which were black - they are now white. I may be able to go one stage richer on the jets, but no detonation so it may not be a problem.
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Old 03-19-2004, 05:06 PM
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c'mon machine shop tom get with the damn program.
the screw on top of the qjet! you know the one screw! the one that holds the air cleaner on! if your running rich you take off the air cleaner by removing the screw on top! all problems solved..
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Old 03-19-2004, 08:58 PM
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Quote:
Originally posted by badknuckles
c'mon machine shop tom get with the damn program.
the screw on top of the qjet! you know the one screw! the one that holds the air cleaner on! if your running rich you take off the air cleaner by removing the screw on top! all problems solved..
All right.. dont start! That magical little screw is called the "idle air bleed screw", or some call it the "idle stop screw" Turning it right pushes the plunger down leaning it out, turning it left will richen it to a point. Just to educate you two on it I found this little picture so you children can learn I appologize in advance, but this is why "I" dought his "25+" years exp. Normal turning is about 3 1/2 turns out or around there, could be 1/4, 1/8, etc...



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Old 03-19-2004, 09:00 PM
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ok buddy just calm down i was burnin your balls.
im sure you know more about carbs than me.
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Old 03-19-2004, 09:06 PM
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Quote:
Originally posted by badknuckles
ok buddy just calm down i was burnin your balls.
im sure you know more about carbs than me.
Sorry.
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Old 03-19-2004, 09:20 PM
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thexton float gage?
thats funny i couldnt make this stuff up. what the h*^ is that thing. ive never pulled a car in the shop and said- well it sounds like the thexton float gage is bad.
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