[bigchevy93]

How do I get an Edelbrock 600 manual choke vacuum secondary to run like my Holley 750 man. choke vac. secondary????

I have read bibles worth of the comparisons but with absolutely zero definitive answer(s)!!!! So many claims, personnel experience differences, dyno posts etc. Its nuts!!!

Any help would be so greatly appreciated, save me back and brain pain!!:smash:

application:

1991 Chevy 1500 ext. cab 3.73 gears ZZ4 motor 10.1 comp. 700R4 sea level elev. rebuilt 1406 Edelbrock 600 converted to man. choke (Ya its a heavy truck but that Holley smoked em off)

 

[69612]

there are tuning circuits on all carbs..

first step. lets check the idle transition circuit.

slowly take the engine rpms up to 2500. then back down to 1500.. holding at each place each time.. then up to 2000 and back to 1200.. then up to 1800 and back to 800... if you can do this.. without the motor stalling. your idle transition circuits are ok..

if you have a flat spot off idle.. start by counting how many turns in you have to turn them in to Lightly seat them.. then remove them.. give the holes a blast of carb cleaner followed instantly by a blast of compressed air. do this 2 or 3 times. . this will usually clean out the idle feed restrictions and the idle air bleeds.. may restore off idle operation..


at idle.. the carb should idle on the fuel limited by the tapered screw tips of the idle mixture screws..

off idle and up thru around 2200 or 2300 depending on a lot of factors.. the engine runs on the idle transition circuits.. and continue while the primary mains start flowing.. there is over lap.. as the transition circuits max out and primary mains start

you will want to use a vacuum gauge and monitor manifold vacuum at 35 mph steady throttle, level road operation.. this is the vacuum reading you should have the primary rod holders just barely seated against spring tension.. this allows the tip in to increase speed/load to lift the primary metering rods slightly.. tip in farther and they come all the way up.. this is the enrichment circuit.

this is just the beginning of tuning..

this is a really great introduction to the AFB carb... it was written for chrysler techs in the 60s..

http://www.mymopar.com/downloads/mtsc/121.pdf

 

[cdminter59]

Can ya get an Edelbrock 600 to run like a Holley 750????

No way an Edelbrock carburetor will ever perform like a Holley. Even with vacuum secondaries the Holley carburetor performs better. The 600 Eddy is a economy carburetor and the Holley 750 is a Hi Performance carburetor. In my opinion for performance you have 1. Holley, 2. Quick Fuel, 3. Demon 4. Quadrajet, and 5. Edelbrock. Even If I had a stock 350 engine and needed a carburetor I would purchase a Quadrajet.

 

[bigchevy93]

With changing the jets, metering rods etc. you still dont think that the edelbrock 600 could come close to touching a stock Holley 750?

I know you have the same bottom end and lose top end but who will ever run their car/truck at high enough RPM to get 600cfm of flow?
This is a street,strip truck but I still shouldnt have such sluggish torque through the RPM range.

 

[bigchevy93]

Thank You Greatly,

Where is your source of the above "beginning" stages of tuning?

 

[69612]

decades of experience in carbs....

reading the 10 or 12 various ages of AFB manuals....

there are tuning manuals for each carb... right from edelbrock.. only thing.. they barely cover the idle transition tuning ... did you see the link i posted???

holleys need tuning to make the best power also.. sometimes you can drop them straight on.. sometimes they need a bunch of stuff done..

wide band air fuel ratio gauges to assist you in tuning will actually make your life easier..

its complicated..

tuning for Wide open throttle is just primary and secondary main jets ..

part throttle and just off idle is where the brute force comes out in a properly tuned carb..

you have not described any issues you are having..

 

[Shaker455]

How do I get an Edelbrock 600 manual choke vacuum secondary to run like my Holley 750 man. choke vac. secondary????

I have read bibles worth of the comparisons but with absolutely zero definitive answer(s)!!!! So many claims, personnel experience differences, dyno posts etc. Its nuts!!!

Any help would be so greatly appreciated, save me back and brain pain!!:smash:

application:

1991 Chevy 1500 ext. cab 3.73 gears ZZ4 motor 10.1 comp. 700R4 sea level elev. rebuilt 1406 Edelbrock 600 converted to man. choke (Ya its a heavy truck but that Holley smoked em off)

You may not be able to.
They have casting issues so it's a gamble getting a goo or bad unit

 

[vinniekq2]

quote from waynep712:you have not described any issues you are having..
Same question and how much have you done so far to correct your issue?

 

[bigchevy93]

went back to stock rods and steel spring on the 600, have .100 primaries and .098 secondary jets. This thing is very close to the stock set up and still stumbles off the line all the way through the rpm range. Its running so lean its ridiculous.

I only had a problem when i substituted this freshly rebuilt edelbrock 600 from the Holley 750 DP!!! Pissing me off. Been dealin with this for over a week now.

 

[bigchevy93]

i swapped from the orange step up spring to a lighter steel spring (one step down) and ive ran the truck on the middle and upper pump shot setting (rich). But the thing still stumbles and wont have ANY power whatsoever on this FRESH rebuild.
Its such bull, but im loosing patience. I guess it could be a bad fuel pump but................. not likely if i can mash the throttle in park and rev. to 6k rpm and have it dialed in. Take off in any gear and this Edelbrock 600 laughs at me!!

 

[bigchevy93]

decades of experience in carbs....

reading the 10 or 12 various ages of AFB manuals....

there are tuning manuals for each carb... right from edelbrock.. only thing.. they barely cover the idle transition tuning ... did you see the link i posted???

holleys need tuning to make the best power also.. sometimes you can drop them straight on.. sometimes they need a bunch of stuff done..

wide band air fuel ratio gauges to assist you in tuning will actually make your life easier..

its complicated..

tuning for Wide open throttle is just primary and secondary main jets ..

part throttle and just off idle is where the brute force comes out in a properly tuned carb..

you have not described any issues you are having..

went back to stock rods and steel spring on the 600, have .100 primaries and .098 secondary jets. This thing is very close to the stock set up and still stumbles off the line all the way through the rpm range. Its running so lean its ridiculous.

I only had a problem when i substituted this freshly rebuilt edelbrock 600 from the Holley 750 DP!!! Pissing me off. Been dealin with this for over a week now.

 

[bigchevy93]

decades of experience in carbs....

reading the 10 or 12 various ages of AFB manuals....

there are tuning manuals for each carb... right from edelbrock.. only thing.. they barely cover the idle transition tuning ... did you see the link i posted???

holleys need tuning to make the best power also.. sometimes you can drop them straight on.. sometimes they need a bunch of stuff done..

wide band air fuel ratio gauges to assist you in tuning will actually make your life easier..

its complicated..

tuning for Wide open throttle is just primary and secondary main jets ..

part throttle and just off idle is where the brute force comes out in a properly tuned carb..

you have not described any issues you are having..

i swapped from the orange step up spring to a lighter steel spring (one step down) and ive ran the truck on the middle and upper pump shot setting (rich). But the thing still stumbles and wont have ANY power whatsoever on this FRESH rebuild.
Its such bull, but im loosing patience. I guess it could be a bad fuel pump but................. not likely if i can mash the throttle in park and rev. to 6k rpm and have it dialed in. Take off in any gear and this Edelbrock 600 laughs at me!!

 

[vinniekq2]

change out your metering rod to the smallest one you have and see what happens,,,

 

[bigchevy93]

change out your metering rod to the smallest one you have and see what happens,,,

I already went back to the stock metering rods and I have fast burn corvette heads with mild cam.

 

[vinniekq2]

how long does it take you to change metering rods? lol

 

[bigchevy93]

3 min but like I said i already swapped those out back to stock and dont have any transport to the auto parts store to buy different combo's! It ran "OK" when first installed, took it out and now its runnin' like burnt trash

 

[vinniekq2]

so if making a huge change makes no difference? maybe look somewhere else? Vacuum leak or something else that can cause a lean mixture? PCV out of the cover? Brake booster leak,,,you are there,

 

[bigchevy93]

already done, no vac. leaks at all. Im thinking about swapping all internals (jets and springs and pump shot) back to stock then work from there i guess???? Got any other ideas??? Thanks man

 

[69612]

i swapped from the orange step up spring to a lighter steel spring (one step down) and ive ran the truck on the middle and upper pump shot setting (rich). But the thing still stumbles and wont have ANY power whatsoever on this FRESH rebuild.
Its such bull, but im loosing patience. I guess it could be a bad fuel pump but................. not likely if i can mash the throttle in park and rev. to 6k rpm and have it dialed in. Take off in any gear and this Edelbrock 600 laughs at me!!

stumbles below 2300 RPM are idle feed restrictions... did you click on the images i posted above and really look at them..

did you try the carb cleaner and compressed air thru the idle mixture holes that blow any dirt out of the idle feed restrictions..

i know somebody posted that that won't work.. its not in the book.. it will only blow thru the idle ports... WRONG. it does work..

do you have any 0.023 welding wire.. a 6" piece would help.. as most of the passages are larger than that... be sure to polish the sides of the wire cut to avoid burrs and scratching the openings..


log in.. check your private messages call me..

 

[bigchevy93]

If the carb is in question and your going to take it off the car a would recommend a rebuild the eldo kit is cheap sold in parts stores and easy to do. Once you rebuild it you can bring it all back to stock and make sure the carb is right they are pretty simple once its all a part you will be able to see if its clean or not or if there is a problem.

This is a fresh rebuild carb. went mudding and got the engine compartment pretty dirty, im thinking its a clogged idle circuit passage and going to remove primary venturis and spray with cleaner in vent tubes etc