Edelbrok heads versus Holley of same flow (actual results)

Right now I have 750 Edelbrok carbs on my fairlane and in my humble opinion they work pretty good. Has anybody done a back to back test against a 750 Holley version of the exactly same engine or better yet a drag strip back to back? I am assuming that I am making around 700 plus hp as last fall it went 10;30 at 127 plus at over 3500 lbs. By the way the SR71 heads are in my basement right now and will be on this spring.

Holley carb will outperform an Edelbrock. The Eddy carbs are good for cruising and for being a little more trouble free, but they don't make power like a Holley does!

I did on my old 351c I will never buy another Edelbrock carb the Holley made it feel like a whole nother engine

BBFTorino wrote:Holley carb will outperform an Edelbrock. The Eddy carbs are good for cruising and for being a little more trouble free, but they don't make power like a Holley does!

This is why I am asking this question as I have 750's Edelbrocks on my car now and they perform excellent and start and the car doesn't stumble or anything. I can handle a tenth or so but I don't want to lose a half of a second in et. My car is a nostalgia type car, in fact I plan on putting a set of spun aluminum disc's on it this year so I can run the meltdown style races that we have here in the midwest. It just looks better to me with the carbs facing forward JMHO.

With the same calibration the AFB will run right with the Holley but remember that the 750 AFB is not a particularly good model and it flows significantly less than something like a 3310 or 4779.

DaveMcLain wrote:With the same calibration the AFB will run right with the Holley but remember that the 750 AFB is not a particularly good model and it flows significantly less than something like a 3310 or 4779.

Dave Edelbrock has a new 800 cfm carb with what they call anular boosters. Have you heard of it yet. I have removed the choke butterfly from mine so and am considering removing the air valve also has anybody tried that that you know of.

57ford custom wrote:

DaveMcLain wrote:With the same calibration the AFB will run right with the Holley but remember that the 750 AFB is not a particularly good model and it flows significantly less than something like a 3310 or 4779.

Dave Edelbrock has a new 800 cfm carb with what they call anular boosters. Have you heard of it yet. I have removed the choke butterfly from mine so and am considering removing the air valve also has anybody tried that that you know of.

I'm not familiar with the 800cfm AFB style Edelbrock carburetor. Keep in mind that Carter AFB's are rated at a different amount of depression(more) than a Holley four barrel which is 1.5 inches of Hg or 20.3 in H2O. I think that the Carters are done at 2". This means that they are "smaller" with the same airflow number.

The problem with the 750 Edelbrock is the same as with a Holley 850 and in particular the 830cfm. When they tried to get more air flow through the carburetor in these carburetors they enlarged the venturi so much that it has very little ventruri shape left it is nearly straight through. This gives less pressure drop/signal for the carburetor to use for metering fuel. The fuel curve and mixture quality suffers and so does performance. Remember that fuel curve and mixture quality trump airflow when it comes to carburetion. This is especially problematic on the primary side of the carburetor.

I've seen some with the weights cut way down on the secondary metering valve to speed up the opening. With a light car this might help performance. Take it out, try it and see how it runs.

I have went to events with a bunch of Nostalgia super stocks and lots of them have the Edelbrock/carter afb style carbs because of rules I guess. Some of them are very fast and are pushing 800 to 1000 plus hp. When I ask them about what they do to the carbs it seems somebody else always does them for them. I guess I have to find an expert that will share his secrets. I know the mopar guys spend lots more money on their engines. It seems like 30 grand is mentioned a lot. And I am way way less than that.

The first rule is to NEVER use the Edelbrock carburetor that's "emissions calibrated". Those were done back in the early '90's to make a 50 states legal carburetor. To meet the California emissions standards they had to calibrate the carburetors about 5% too lean. They ran reasonably ok and they met the emissions standard's requirements. That was then.... Now with gasoline that contains 10% ethanol the carburetor is now a few % leaner again. Now it is so lean it won't run well....

Another thing that I've seen on an Edelbrock AFB was one that I had on a 432 cubic inch big Chrysler. That engine made a little over 500 horsepower with my 950HP carburetor. Then the customer brought in a 750 Edelbrock carburetor and if I remember correctly it was down about 60 horsepower, terrible! His was not an emission calibrated model but the carburetor was far too lean. I spent some time changing out the jets trying to get it rich enough. I never could and I even took the jets out of the secondary side and did a pull. Still lean. I found out later that some of them were manufactured with secondary boosters that were not machined correctly and it would never get richer than about an 85 jet size.

They can be made to run really well if calibrated correctly.

DaveMcLain wrote:The first rule is to NEVER use the Edelbrock carburetor that's "emissions calibrated".  Those were done back in the early '90's to make a 50 states legal carburetor.  To meet the California emissions standards they had to calibrate the carburetors about 5% too lean.  They ran reasonably ok and they met the emissions standard's requirements.  That was then.... Now with gasoline that contains 10% ethanol the carburetor is now a few % leaner again.  Now it is so lean it won't run well....

Another thing that I've seen on an Edelbrock AFB was one that I had on a 432 cubic inch big Chrysler.  That engine made a little over 500 horsepower with my 950HP carburetor.  Then the customer brought in a 750 Edelbrock carburetor and if I remember correctly it was down about 60 horsepower, terrible!  His was not an emission calibrated model but the carburetor was far too lean.  I spent some time changing out the jets trying to get it rich enough.  I never could and I even took the jets out of the secondary side and did a pull.  Still lean.  I found out later that some of them were manufactured with secondary boosters that were not machined correctly and it would never get richer than about an 85 jet size.  

They can be made to run really well if calibrated correctly.  

On the larger models ... the as sold needles & seats are only .089" orifice.
THOSE become the Wide Open Throttle fuel restriction, not the jetting.

rmcomprandy wrote:

DaveMcLain wrote:The first rule is to NEVER use the Edelbrock carburetor that's "emissions calibrated".  Those were done back in the early '90's to make a 50 states legal carburetor.  To meet the California emissions standards they had to calibrate the carburetors about 5% too lean.  They ran reasonably ok and they met the emissions standard's requirements.  That was then.... Now with gasoline that contains 10% ethanol the carburetor is now a few % leaner again.  Now it is so lean it won't run well....

Another thing that I've seen on an Edelbrock AFB was one that I had on a 432 cubic inch big Chrysler.  That engine made a little over 500 horsepower with my 950HP carburetor.  Then the customer brought in a 750 Edelbrock carburetor and if I remember correctly it was down about 60 horsepower, terrible!  His was not an emission calibrated model but the carburetor was far too lean.  I spent some time changing out the jets trying to get it rich enough.  I never could and I even took the jets out of the secondary side and did a pull.  Still lean.  I found out later that some of them were manufactured with secondary boosters that were not machined correctly and it would never get richer than about an 85 jet size.  

They can be made to run really well if calibrated correctly.  

On the larger models ... the as sold needles & seats are only .089" orifice.  
THOSE become the Wide Open Throttle fuel restriction, not the jetting.

Could be.

Before the engine goes on the dyno this spring we will have to really do some jet and metering rod changes for fine tuning. I am going to try and do a run in with the edelbrocks on my run up stand before I go on the dyno. I also have a Weiand top for the tunnel ram with 2 dominator 1050's for it. In fact yesterday I did some assembly work for the linkage as they are sideways as I call it. This is all used stuff of course. The one dominator I bought new many years ago and the other one is a 400.00 ebay one that I put a kit in. This may be a little more expensive dyno session at R&R in Spring lake park in Mn which is about 30 miles from my home.

Before the engine goes on the dyno this spring we will have to really do some jet and metering rod changes for fine tuning. I am going to try and do a run in with the edelbrocks on my run up stand before I go on the dyno. I also have a Weiand top for the tunnel ram with 2 dominator 1050's for it. In fact yesterday I did some assembly work for the linkage as they are sideways as I call it. This is all used stuff of course. The one dominator I bought new many years ago and the other one is a 400.00 ebay one that I put a kit in. This may be a little more expensive dyno session at R&R in Spring lake park in Mn which is about 30 miles from my home.

Sorry for the double post

57ford custom wrote:Before the engine goes on the dyno this spring we will have to really do some jet and metering rod changes for fine tuning. I am going to try and do a run in with the edelbrocks on my run up stand before I go on the dyno. I also have a Weiand top for the tunnel ram with 2 dominator 1050's for it. In fact yesterday I did some assembly work for the linkage as they are sideways as I call it. This is all used stuff of course. The one dominator I bought new many years ago and the other one is a 400.00 ebay one that I put a kit in. This may be a little more expensive dyno session at R&R in Spring lake park in Mn which is about 30 miles from my home.

Have all of the stuff that you want to test all worked out before you put the engine on the dyno so that you can move through things quickly and have time to try a lot of stuff. I'd strongly recommend having some carburetor spacers with you to try as well. Make sure that your linkage will work with them installed etc. I always like to try a 1 inch 4 hole, open,a merge and no spacer because you never know what will be best.

Be sure to test with and without your aif filters. I'd also bring along some pipe that you can stick onto the header collectors to experiment. Make sure that the timing mark is correct and easy to read.

Thank you for the advice Dave as they say "this ain't my first rodeo" but I usually forget some stuff due to just a bad case of CRS that kicks in. I will also have the SR71 heads on it. So should be fun.

57ford custom wrote:Thank you for the advice Dave as they say "this ain't my first rodeo" but I usually forget some stuff due to just a bad case of CRS that kicks in. I will also have the SR71 heads on it. So should be fun.

The reason I said all of that was just because I hate it when the testing is all done and then someone thinks of something else that would have been cool to try. I think it'll interesting to see what sort of power those heads make with the dual Dominator setup I think it'll be impressive.