edelbrock to holley conversion

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63dartman

63dartman

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I am swapping out my edelbrock 750 for a holley 650 double pumper and not sure on how to do it. Do I need any special adapters bolting a square bore holley to an edelbrock rpm intake? I know I will need the dual feed setup and correct linkage parts but not sure about the base.
 
Yes you will need a speadbore to square bore adapter plate which usually hurts flow pretty well. So keep that into consideration. Linkages are different, i run a lokar throttle and kickdown cable and i've swapped with no issues. Dual feed line as well. Watch your hood clearance with that spacer.
 
I believe the Edelbrock is a squarebore. I think you won't need an adaptor. Why are you switching? IMHO, the AFB design is better.

Karl
 
What is the adapter for? I put the carb on and it opens both butterflies without any interference. I don't quite understand the need for the adapter.
 
this is my intake

side_5.jpg
 
Based on the questions you are asking you don't have a lot of experience with carbs. The Holley double pumper will take a lot more tuning skill to dial in than the vacuum secondary Edelbrock.

IMHO, you would be better off staying with the Edelbrock carb or if you need a new carb going with somthing like a 650 Edelbrock or a Holley 670 Street Avenger carb.
 
LOL, I want a Holley because they have better performance than edelbrock. Most everyone tells me that for out of the box drop in and run use the edelbrock. For performance use the Holley. plus it has a really cool dual feed:) I don't have any expierience with Holley carbs but I guess I will now. I'm not scared:) YET!!
 
The RPM intake will accept a standard Holley square pattern carb.

As far as linkage goes, throttle linkage shouldn't be too big nof a deal. Kickdown linkage shouldn't matter because you don't want a double pumper with an automatic.
 
63dartman said:
HUH? Why don't I want a double pumper with an automatic? Did I screw up?
Click to expand...

Sorry i misread your first post, i thought you had a spreadbore holley.

And you dont want a double pumper with most automatics. How high of a stall converter do you have? I've tried messing with a 650 holley vac sec, a used one. I've never had any luck with previously abused holleys for some reason which is why i still run my 650 avs edelbrock. Prepare to cuss a lot with venturing into the world of holley lol.
 
Goody, now I'm really confused. I thought a spread bore has larger secondaries than the primaries. The square bore has all equal size bores and butterflies. My Holley I just picked up has dual feed and all the butterflies and bores are the same size:read2: I know the Holley carbs can be finicky to setup but, I'm up to the challenge, I've got a couple of friends that can bail me out if I really screw it up:)
 
With my 750 holley DP & 727 w/3400 stall & 4.10's I can light em' up no problem. So thats enough power for me.
 
For a race car with a fairly high stall converter, deep gears and no requirement for fuel economy, a double pumper might be OK with an automatic. On the street, it won't be as smooth or tractable. With a tight converter and tall gears, you will have bogging problems. No amount of pump shot can compensate for a 750 CFM carb snapped wide open at 2000 RPM. It just won't work well. (You can learn to drive around this by not using full throttle at low RPM, opening the secondaries slowly etc...)

Have you read the recommendations on Holley's website? Against the outside chance they know something about their products, you may want to check it out. www.holley.com/TechService
 
Yes, I did read the Holley website and I even managed to use their carb selector........guess which one showed up? I posted that I bought a 650 dp not a 750dp. I understand your trying to help me but don't try to insult me. I'm just trying to put a carb on my car.

Have you read the recommendations on Holley's website? Against the outside chance they know something about their products, you may want to check it out. www.holley.com/TechService
 
63dartman said:
LOL, I want a Holley because they have better performance than edelbrock. Most everyone tells me that for out of the box drop in and run use the edelbrock. For performance use the Holley. plus it has a really cool dual feed:) I don't have any expierience with Holley carbs but I guess I will now. I'm not scared:) YET!!
Click to expand...

The difference in performance would only be something you would notice if you are running the car on a dyno or racing it all the time. For a street or street/strip car it is much much more important to have a carb that gives you good low mid range throttle response than a HP or two more on the top end. You also want a carb that will be without any bad street manners. There is a reason that with very very few exceptions all the performance engines from the muscle car era came with vacuum secondary carbs.

As far as dual feed is concerned that is a poor reason to select a carb. All Holley 4150/4160 series carbs with center hung floats whether they are mechanical secondary (double pumper) or vacuum secondary have dual feed and you can buy a dual feed kit for your Edlebrock carb if that is important to you.

If you already have the 650 go ahead and give it a try but I think you will find that there is little or no seat of the pants difference in perfromance and you will definately have a much more difficult time trying to get it dialed in. Hold onto your Edelbrock, I bet you will eventually go back to it.
 
Go ahead and try it! You can always take it off and switch back. Be sure to use the mopar holley throttle lever extension, makes it a lot easier to hook up the linkage. I have a Holley 650 DP on my 340, I have a big cam, M-1 intake with a 1/2 spacer, 4.10 gears and a 4-speed and the carb works awesome!! Maybe you could describe your engine and drive combo? So what if you have to monkey with the Holley carb, atleast you will learn something new. Is the carb new? I would also get some of the "blue" reusable bowl gaskets if you don't already have them, makes things easier if you have to change jets.
 
Thanks for the encouragement, I guess that's the whole point. I Don't know anything about holley carbs and I want to learn. I can't think of any better way than throwing one on and playing with it, also finding all the doucumentation and internet sites for holley carbs. If I have trouble with the mechanical secondaries on the street then I can get one with vacuum secondaries. I have a good lead on carbs from a guy I met at the track. He rebuilds them in his spare time and does good work. Prices are also very nice too. I think that Holley has a much broader selection of carbs over Edelbrock too. I can always save the 650dp for my 70 dart when I start on it too. Thanks again guys.
 
The problem with a double pumper on a street car with an automatic is when you floor it all throttle plates will be wide open whether the engine needs the air or not. The result is a bog. With a vacuum secondary carb you can floor it and the primaries will be wide open and the secondaries won't come in until the engine needs the additional air. Much better for an automatic. If you like Holleys I would go with a vacuum secondary.
 
Forgot to mention, I knew a guy who had a 650 DP Holley on his 1970 Duster 340 auto and he said it ran the best with that carb! He had an aftermarket intake, headers, mild cam and 3.91 gears, nothing special! :toothy10:
 
I've been tuning carbs for 30+ years so I'll try to sum this up with as few words as possible. Edelbrock carbs generally run well right out of the box, very easy to tune and adjust( jets,rods,floats, pump shot), and hold the adjustments well. If you want to play with a Holley then get a complete jet kit, nozzles, power valves, pump cams and bowl gaskets and be prepared for lots of testing until you get it dialed in. You can get a Holley to run well but it's a lot of work and time. Good Luck and have fun.
 
Ok, guys. Here's my input. Take it or leave it.
I got a Eddy air gap on the Duster. I switch from the 750 Eddy
carb for the street to a 750 Holley dp to go racing.
It bolts on with no problems. I took to linkage adaptor and
elongated one hole to work on both carbs.
The Eddy is great on the street, but I get better performance
out of the Holley at the strip.
I have the different fuel line set up for each carb. Just a
short section of hose to get to the filter.
I don't recomend doing this, but it works for me. So I don't
see any problem switching over.
 
hey, just curious, is the 750 eddy a vac secondary? Just throwin this out there. I've got a 650 holley vac secondary you might be interested in (im not sure what you are running for engine) but i am looking for a 750 vac secondary carb because i decided to go with a bigger engine than i originally planned.
 
No Eddy is vac secondary. The Performers had an air baffle like the AFB they were based on.
 
I'm running a Holley 650 DP on my 360 in my Ramcharger. 727 with a tight converter, 3.55 gears and 33" tall tires no problem. It eats gas but no driveability probelms at all.

Tuning a Holley is not a black art, it just takes some paitence and knowledge. I say go for it and learn in the process.
 
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