need help with Edelbrock carb
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
need help with Edelbrock carb
I have a electric choke 600 cfm Edelbrock carb on my 84. Everything is hooked up and the engine starts right away every time, even when cold. The choke opens when warm and at idle it sounds good. If you rev it too high (3000rpm and up) it starts popping. While driving it under moderate acceleration it backfires and hesitates. I tried using Edelbrocks tuning instructions. It said to turn the fuel screw until it changes the rpm. On mine it doesn't change at all. At least I can't tell. If I turn the left screw all the way in it will start popping at idle. I know it's not a vacuum leak because I took the hose off for the power breaks and put my thumb over it. It reved and sounded different with my thumb off the tube. The timing is set at 6 deg. It's a rebuilt carb. It was rebuilt by Edelbrock. I hope someone can help.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
It may be going lean at higher rpms. The screws you are messing with are idle mixture screws. They are pretty much out of the picture at your problem speeds. The new Car Craft Magazine has a brief article on tuning the Edelbrock/Carter carb.
RACE ON!!!
RACE ON!!!
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
The Edelbrock is a nice piece as carbs go, based on the old Carter AFB, AVS carbs. But my God, why are you messing with such ancient technology on an FI car? Being the old fart that I am, I grew up with them too but as soon as I get around to it, I'm Ebaying every old carb I have lying around, including the old LeMans type Holley from a Holman & Moody 427.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Well to honest I was never happy with the Crossfire. Even with an x-ram and 2 inch throttle bodies. I was making my own chips for a 7747 ecu and still wasn't happy with it. It was just so prone to vacuum leaks and never had the power I wanted. So I got the bright idea to swap to an Edelbrock TPI setup. That was a mess. The car never ran with it. I had one wiring harness fire after another and I just got sick of messing with it. So now I'm planning on building a 427 small block. It will have stand alone engine management but until then I'm running a carb on my built 350 just to get me buy. I agree FI is the way to go. The carb is just for until I get my new motor.
Safety Car
Joined: Dec 2002
Posts: 3,655
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From: Charleston SC
Just to ask a stupid question but you did replace the distributor when you converted to carb Right? If you did is your timing advancing properly when you rev it? I would check both the mechanical and vacume advance to make sure they are working corectly. When I swaped my 84 to a carb it was giving me problems similar to what you describe turned out to be a stuck weight on the mech adv. 
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Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Yes I swapped the distributor. Would have been funny if that was my problem. Anyway I haven't checked the mechanical advance. I put in a new billet distributor so I doubt that's the problem but you never know. I will add that to the list of things to check. I guess it could be that the advance is too much or too little for my setup. When I check the advance it should be 36-38 deg right?
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by FD2BLK
turned out to be a stuck weight on the mech adv.
I've seen quite a few of the old mechanical advances do that. Go buy one of those $10 advance kits with different weights and springs to repair it (even if it's NOT frozen) and it'll wake it right up! If you can get away with it, throw the vacuum advance away and set your timing for max power at total advance (probably 32-34) and if you can still crank it when it's warm, it'll kick your ***!
Drifting
Joined: Dec 2002
Posts: 1,474
Likes: 4
From: Tracy CA
Originally Posted by 6spd
did you screw with the secondery mixture screws also you might have a bad power valve.
Primaries are easy to a make slight changes with just the metering rods.
Backfire: Through the carb or out the exhaust?
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Have you tried advancing your timing? 6 degrees sounds a little shallow-I'd try at least 8. Is it backfiring thru the carb or exhaust?
Last edited by rick lambert; Oct 20, 2004 at 09:41 AM.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
I ran my 64-327 very modified at 10 with a Holley 650 DP/4 squirter.
I'm just trying to say it's either in the dist. or timing. Is the valve lash set properly? I wouldn't think the carb itself would be causing the backfiring. I've messed with to many of those.
I'm just trying to say it's either in the dist. or timing. Is the valve lash set properly? I wouldn't think the carb itself would be causing the backfiring. I've messed with to many of those.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Well the valves do need set. The engine hasn't been run for over a year and when it runs now I can hear a very slight tap on the drivers side. I was going to reset the valves but I didn't think that could be causing my problem. I have a long checklist of things to run through. First I'm going to pull all the vacuum lines and cap everything just to eliminate that as a possibility. Then I'm going to take off the gas cap to make sure it's not a clogged vent system. Then check timing and fuel pressure. I forgot to mention I am running a Holley blue fuel pump with a regulator. And if it still gives me problems then I'll check the mechanical advance. Ohh and I want to make sure that the distributor didn't skip a tooth somehow. That's about all I can think of. Any other ideas?
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
Okay, I set the timing back to 8 deg. I double checked to see if the distributor was off a tooth,(It's not). I tried raising and lowering the fuel pressure. That didn't fix the problem. I checked, and it is advancing the timing under throttle but I can't tell how far. My timing gun doesn't have the ***** on it to see how far it's going. I can try and borrow one tonight that does. One more thing. This distributor is an aftermarket "performance" ebay special. Could the springs and weights just be too much for my application? Are the springs color coded to tell you how much advance they give? Mine are black.
Race Director
Joined: Dec 2000
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From: El Paso Texas
Originally Posted by Phobos84
Well the valves do need set. The engine hasn't been run for over a year and when it runs now I can hear a very slight tap on the drivers side. I was going to reset the valves but I didn't think that could be causing my problem.
Any other ideas?
Any other ideas?
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Seems to me you've answered the question to your problem "car sat for a year and I can hear" that's not an aqurate quote-but-if your car sat for a year and you can hear a tapping sound-it's more than likely a lifter-their hydraulic-and they can loose their fluid (oil) it's not pumping back up. There are some snake oils (some actually work) that help unstick a stuck lifter-keep in mind-if you do have a stuck lifter it can cause damage to the valve train-especially the cam lobe.Get a stethascope-or some guys use a screw driver to isolate where that noise is coming from. If it's definetly a lifter pull the valve cover and see if it's lifting all the way and closing all the way-sounds like an exhaust lifter is stuck.This is just my .02 cents worth.
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 2,876
Likes: 764
From: Sligo PA
As far as the valves go I never re-set them after I put in my roller cam. Comp cams said that I would have to go in and readjust the valves. So I pulled the valve covers and re did them today. It sounds much better. No tapping and seems to run smoother but it still pops. I did learn something. The distributor is an adjustable vacuum advance. It didn't come with any directions but I think it can be adjusted with a allen wrench. My question is what does that do? I have never used one of these before. Does it only change the idle timing or does it somehow change mechanical timing?