For performance which is best (carbs)? I have modified /6 225. I have edelbrock on the car now but, the carb seems to load up on burnout at track, and has bad flat spot off idle when engine warms up. The carb is a 500 cfm edelbrock vac. sec. I have rebuildable Holley 600 cfm vac. sec. What does everyone think??

It really depends on your engine buildup and carb settings. I personally prefer the Edel 500 for street/strip use. Power-wise, you can do well with either brand, but it depends on tuning.

Lou

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Home of Slant6-powered fun machines since 1988

I thought edelbrock was a low maintance or low adjustment carb. I have to tune this one all the time, and never have got it just right. I think I want to try the holley.

In my experience the Holley has more tune-ability, but the edelbrock is a low maintenance carb. If it were me, I would run the edelbrock for the street but try a Holley for absolute maximum performance at the track.

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Casually looking for a Clifford hyperpak intake for cheap.

Regardless of the carb, some tuning will have to occur...I mean most of these carbs off the shelf are setup for a Ford or Chevy Small block....

Either way the best thing is to get a book on tuning/ rebuilding each carb so you have something to go from instead of fumbling around in the dark on adjustments, and waiting for someone to help with your carb tuning.

Do you have a number off the airhorn of the Holley 600? (2818,1850-?,80457...)

Also please post your build up, tranny, rear ratio, and cruise rpms (65mph = ??? rpms) so we don't have to search all over again to get you some 'input'....


For the Holley go with rebuild kit 37-119, make sure to pick up a spectre backfire protection valve if your carb was made before the mid-90's (the new ones come with that now), also record what it is equipped with for jets, power valve(6.5), pump cam(and screw position). The best two items to add to it are: vacuum secondary quick change pod, and the secondary metering block, along with a secondary spring kit....

I'd wrather see you try and dial in the Edelbrock, it sounds like something just wasn't tweaked right for your build, the Holley may not like things either....

Got vacuum gauge, right?

-D.Idiot

The number on the airhorn is: list-1850-2

that is a 600 holley.

I presume you are using headers when you say you say you are running a modified /6. The off-idle bog you are having is due to the fuel condensing from the air when you accelerate. The airflow at low RPMs is not high enough to keep the atomized fuel entrained in the air and there is not enough vacuum to vaporize the fuel.

You will have this problem whether you are running the Edelbrock, the Holley, a QuadraJet or any other low restriction carb. I have spoken with a Chevy six-cylinder truck owner who runs headers with his stock intake & carb and he also has this exact same problem.

The simple cure for this problem is to add heat to your intake manifold. If you have a Clifford intake, hook up the water jacket. If you have a Offenhauser intake, you can fabricate a plate to mount to the bottom of the manifold in place of the exhaust manifold heat riser. Splice it into the 5/8" return hose from the heater core. I have done this and have completely eliminated my off-idle bog from my QuadraJet.

Your other option is to compensate for the fuel condensation by adding more fuel with a richer power step. The Edelbrock metering rods with the largest difference between the power step and the cruise step are:

PN .......... Size Difference ........ Cruise/Power Size

#1459 ..... 0.0280 .................... 0.075 x 0.047
#1419 ..... 0.0330 .................... 0.075 x 0.042
#1458 ..... 0.0380 .................... 0.075 x 0.037

Another option, which I haven't tried but others have, is to add a screen below the primary barrels to increase turbulence to help keep the atomized fuel entrained in the airflow. This would reduce the flow capacity of your carb somewhat but would be great for catching anything you might drop down your carb.

If you don't want to make one yourself, I have an intake manifold heat water jacket for sale.

Frank Raso
Raso Enterprises
http://cars.rasoenterprises.com

Three words:

AFB

...what DI and Frank sed are right on target, too. There is no 4-barrel that's going to run great right out of the box on a slant 6. Time to hone your tuning skills.

D/W

P. S. - What is a vacuum secondary Edelbrock? ...I guess the case could be made that the terminology is tecnically correct

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If it ain't broke, fix it!

It's like a dual quad except when manifold vacuum approaches 0-3"Hg the second Edelbrock starts working....


LOL....

If you just want to 'tinker' with things (or need a carb to rebuild to keep your hands from doing something they shouldn't...)

You can start with these settings for the Holley:

63 jets in the primaries (depending on weather you may have to size up to 65 or can be down to 58/59's...)
72's in the secondaries (can go less)
Black secondary spring to start, then try brown when you have the primaries dialed in
10.5 power valve
Orange 466 pump cam in the #2 position , may have to go to a green or pink depending on how the 'shot' looks

-D.Idiot

Thanks for info, I'm still learning.