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Old 09-27-2004, 02:40 PM
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Exclamation Edelbrock Carb help....

We (me and my father) swapped carbs on my Camaro this past week. It had an old quadrajet, that was quite tired, and needed to be retired.

My dad bought a brand new, 600cfm Edelbrock, manual choke, 4bbl carb for his motor build up, but was too small. So rather than send it back, put it on my car.

Well we adjusted the necessary things, tested vaccuum, etc as my dad has been doing this since he was a kid.

We adjusted the (park) idle, and it wouldnt stay running below 1300 RPM (which is way high), and fluctuated a lot. Put it in gear, and it drops to 500-600 rpm. Problem is, when you put it in gear, it trys to lurch forward, and jumps a bit. Then when you barely touch the gas, it launches forward.

We were suggested to check the float levels, as they may be too low. We have checked everything else.

Anyone recommend anything else? Or does this sound like a float level issue?

(Motor: 350 sbc. Edelbrock performer intake, L82 Cam, th350 tranny).

Thanks in advance for your help.

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Last edited by Toy71Camaro; 09-27-2004 at 04:31 PM.
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Old 09-27-2004, 04:38 PM
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Could be a vacuum leak. You need to use an adaptor plate between the carb. and the performer intake. Phil
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Old 09-27-2004, 05:51 PM
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i agree, sound like a BIG vacume leak

it should idle fine...check your timing also
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Old 09-27-2004, 05:54 PM
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After you have checked for any vacuum leaks around the base of the carb and hopefully find none do the following.

After the engine has warmed up to operating temperature & the choke is fully open, attach a vacuum gauge to full manifold vacuum. Then adjust the two air/idle screws (slowly in or out) to achieve the highest vacuum on the gauge. A good starting point for these two screws is 1 1/2 turns out. Now re-adjust the curb idle screw to lower the idle RPM. You should get the idle RPM to around 850-900 in Park. It will drop to around 700 RPM when in Drive. You may have to make a small re-adjustment of the air/idle screws after resetting the curb idle.

Recheck your initial and Total mechanical timing (be sure to have the vacuum advance hose dis-connected and plugged when checking and/or setting the timing. Re-connect it after the timing has been set.) Look for around 10 degrees initial and 34 degrees Total mechanical all in around 2500 RPM. Adjust as required.
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Old 09-27-2004, 06:08 PM
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Thanks for the input fella's.


It should not require an adapter plate, both are square bore.


Also, we checked the vacuum, it measured up (used the right side (driver) vacuum port, and adjusted the 2 screws based upon best vacuum readings, then set the idle down. And thats the point in which we are having the problem.



It runs great otherwise, just got to get past 1500 rpm, then runs like a champ..
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Old 09-27-2004, 06:16 PM
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Quote:
Originally posted by Toy71Camaro

Also, we checked the vacuum, it measured up (used the right side (driver) vacuum port, and adjusted the 2 screws based upon best vacuum readings, then set the idle down. And thats the point in which we are having the problem.



It runs great otherwise, just got to get past 1500 rpm, then runs like a champ..
This is a different problem than what you originally posted. I assume you now have the idle speed where you want it to be.

Your bog from idle up to 1500 RPM can be a couple of things. The first thing I'd suggest is to switch the vacuum advance hose to the full vacuum source. Re-adjust your curb idle after doing that and test drive. If you still have the same bog, then you need more accelerator pump squirt. You should be able to increase that by adjusting the linkage on the accelerator pump.
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Old 09-27-2004, 06:19 PM
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Sorry for the confusion. We are at the same point in which my original post stated. We have tested the vacuum, and tried adjusting the park idle down, but when we adjust it down to where it should be (which is what its at now), it still tries to fluctuate too much, and when you drop it in drive, almost dies, and starts lurching forward. then when you barely touch the gas, it literally leaps forward (enough to break the rear tires loose).
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Old 09-27-2004, 07:00 PM
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yes, the carb is square flange, the Performer intake is both square & spread-bore bolt pattern, if using a square flange carb on a Performer intake,you should have a thin metal shim to sandwich between 2 gaskets, it gives a much better sealing area
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Old 09-27-2004, 07:04 PM
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un plug everything (vac lines)from the carb and see if you can get it to idle.

them plug thenm in one at a time to find the bad one

600 edelbrocks are jetted real lean

re check linkage to throttle, and choke settings
this is weird problem
the idle thing we can fix but, the lurching thing
is bothering me.
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Old 09-28-2004, 10:32 AM
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Thanks for the further input.

Will try the vacuumn line test this weekend (or hopefully sooner).

About this shim/adapter plate, should that be found at your local auto parts store? or is that something mail order only (ie. summit/jegs)?

Thanks again!
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Old 09-28-2004, 12:40 PM
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Jeg's part # is 350-2732. They call it a "square flange plate". Any auto parts store that carries Edelbrock will have it. Phil
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Old 09-28-2004, 04:02 PM
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Thanks for the research Figure8. I have found one local, and should be able to pick it up tomorrow

Thanks for you guys' help. I will report back with my findings!
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Old 10-01-2004, 12:56 PM
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Update:

Installed the Carb Plate last night. Pulled out the vacuum gauge, and timing light.

Seemed to run a bit smoother, but not as it should quite yet.

We re-timed it, in which we had to retard the timing just a bit. Which helped.

We were adjusting the fuel/air mixture screws and when adjusting the passenger side screw, it didnt seem to do anything. So we think it might be a plugged Jet. we are going back that screw all the way out, and blow it out to make sure.

If its still rough, we are going to take a look and check to make sure the float bowls are correct.

Any other suggestions? or comments about what to do next?
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Old 10-01-2004, 02:22 PM
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YOu mentioned the carb is new and the only thing that has been changed on your engine, and no matter what you do will not correct itself............send it back!
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Old 10-01-2004, 04:06 PM
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357... we are going to make sure the Jets and floats are OK, and if that dont work... then sounds like you might have the right idea.
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