I need some Carb 101

[Headrope]

I do not (repeat: DO NOT) want to start an Edelbrock versus Holley debate, but wonder what the pros/cons are with Holleys. And what does the Holley lingo mean (double pumper, etc.)?

I've always run a 600 cfm Edelbrock or 625 Carter Comp Series carb but am feeling a bit saucy. My engine is a mildly built '68 383 (.40 over 10.1 flat top pistons, Street Hemi grind Purple Shaft cam, Edelbrock Performer intake, stock heads, stock exhaust) with a 727 automatic and 323 rear.

[69chargeryeehaa]

i run a old carter competition serries 750 cfm carb, which is the same as a eddy #1408 performer carb.  basically the same setup as yours except 440.  when i got the car it had a off idle bog/hesitation, but after learning all about the carb, reading my plugs, and getting a calabration kit, i've got it running perfect and resolved all my problems.  i think the holleys are better carbs, but harder to setup and get perfect, but when setup properly they feel like FI, but the eddy's are alot more simple carbs and do the job just fine.  i guess it's all preferance, i'll stick with the eddy's cause i know it inside out now.  either carbs can be tuned to perfection, but the eddy's are alot eaiser to setup, if you want bolt-on easy to setup carbs, go with the eddy, if you have the time and $ and want to setup a holley properly then go that route.   

[terrible one]

Holley double-pumpers have a pump on both the primary and secondary sides, hence the name double pumper. These are the ones you will see with a fuel line going to each side.

[471_Magnum]

Holley double-pumpers have a pump on both the primary and secondary sides, hence the name double pumper. These are the ones you will see with a fuel line going to each side.

Half right. Double pumpers have accelerator pumps on both primary and secondary. It's got nothing to due with the dual feed fuel line though. Any Holley 750 CFM and above carb will have the dual feed, double pumper or not. Smaller carbs will have a single feed and a transfer tube.

Back to the original question: A Holley offers much more "tune-ability" than an Edelbrock/Carter. Ultimately they can perform better, but they are harder to set-up. Guys who claim Edelbrocks/Carters perform better generally got in over their heads with a Holley.

That said, the Edelbrock/Carter is a fine choice in most street applications, but there is a reason 99% of racers use Holleys. I can rebuild and tune an Edelbrock for the street in about an hours time. Takes more time on a Holley, but you can get it right to the edge.

[69chargeryeehaa]

i agree, from what i've heard, the holley's can be made to run better than a eddy, but if you don't have the time/knowledge, and want a simple easy to tune carb the eddy is a better choice.  i'm just using what i got with the car, if it were for myself, i'd probally go with the holley.  it might be a better choice to run a eddy if you don't want to take the time to tune a holley, better to run a eddy than a mis-tuned holley.

[Chryco Psycho]

there are far more adjustments & parts available to make the adjustments with Holley Or Demon style carbs there are 7 basdic circuits in a carb , with Eddy/ Carter some are limited in adjustment , some cannot be adjusted without a drill or epoxy , while the best Holleys have as many as 50+ different parts to make an adjustmnet to a given circuit   so they can be dialed in exactly with patience & knowledge

[74Charger]

I myself just swapped out my dual carbs.  I had Holleys and switched to Eddy's.  Like the others have said with knowledge and patience the Holleys seem to be a better carb.  But if you do not have both the patience and knowledge (like myself).  You are always going to be pulling your hair out messing with them.

  I knew very little about carbs a month ago.  And the holley's were way over my ability.  Seemed to be too complicated for me.  But the Eddy's were so much easier to setup and understand.  Jets, rods and spring changes are a breeze now.  And I feel much more comfortable with any changes that might need to be made with the carbs.  So I guess it boils down to your what you are comfortable with.  And if you have the time, patience and knowledge to deal with the Holleys. 

In my opinion.  For whatever its worth. If you want something that is easy to understand, easy to work on, understand and good realibilty.  I would go with the Eddys. 
If you want a finely tuned carb and get that perfectly tuned carb, have the time, patience, knoweledge, and someone to help you through it.  Buy the Holley's   

Good luck with whatever way you choose to go!

[Headrope]

Guess I'll be sticking with Edelbrock (or Carter, same thing) then.
I'm a chronic tinkerer when it comes to the carb already. Turn this screw a hair; turn the other one - I can't leave them alone. The last thing I need is more to play with.
Thanks for the help folks.

[Duey]

Headrope, I was a member of the "I love my Carter Thermo-quad" club until I could no longer keep the beastie tuned and running smoothly (couldn't find the crack in the phenolic resin main body  ).  I now have a nice Pro-form 850 waiting to go on the engine and I intend to have the guys in the dyno shop help me tune the carb while I get the motor dynoed this summer.  Hopefully I won't have to worry about all the fiddling around because it will be dialed in and tunes as best as possible.

Cheers,
Duey 

[Headrope]

I've been there too, pard. Those mystery cracks are why I left the thermoquad world and got an Edelbrock.
It's really too bad nobody makes the Thermoquads with a normal body. The fuel economy primaries and insanely large secondaries were incredible.

[Duey]

Yup!  Going from 1 5/16" pri to 2 1/4" sec was insane! 

The biggest thing for me will be the four corner idle air adjustments on the Pro-form (I think the Holley 4150 HP's also have that feature, I think).

Cheers,
Duey

[Ghoste]

Headrope, I've run both carbs in a similar setup to yours.  The pros and cons have all been pretty well covered here and like you, I can't seem to leave stuff alone.  I left the Eddycarter on  my car for a long time just for that reason even though I knew the Holley would offer beter performance.
A Holley came my way for next to nothing so against my better judgement, I put it on.  After some initial fuss getting it dialed in (not even done yet to my satisfaction), I have to say that I so much happier with the way the car runs that I don't know if I'll ever go back to a Carter style.
I think before when I had Holleys, I was always looking for an extra edge so it seemed like I was forever changing things and I don't know if I've matured or just learned to leave well enough alone when it reaches the sweet spot but other than some final tuning to be done now that the good weather is back again, I don't feel a need to tinker with it like I did years ago when I used Holleys.
Just my experience though.  I'm sure many guys can give an exact opposite version.

[Headrope]

Figures. I decide to go one way and then temptation tries to change my mind.

I have the opportunity to buy this carb (description and pics attached) for a decent price. The person selling it claims to have been told it "is in perfect running condition and the guy that i recieved it from seemed to be an honest person to me. It would be best if you were to come look at it for yourself as i am familiar with some aspects of car repair but have yet been into the carb category."

I'd love to get the carb, but don't want to spend $100 on what may or may not be a bargain. Any questions in particular I should ask (I don't know squat about Holleys - hence this thread)?

Is there a casting number of something I should ask for a pic of to help ID the carb as in fact being what the seller claims it to be?

How much would it cost to rebuild one of these things, if needed?

Any replies helpful. Here is the description and some pics:

4 barell 750 double pump carburator by Holley Performance. In good working shape, has anodized aluminum line, fuel adjuster, and extras. Could use a good cleaning but works fine.

[dodge freak]

With the 3.23 gears and stock exhaust you be unhappy with that carb. Those D.P. carbs are great if you have 3.91 gears and headers but in your car you should go with a vacuum secondary carb. You can run that one but you have to give it only half the gas until your rpms are over 2500-3000. I ran one with 3.23's and had fun on the freeway with it but from a dead stop it was just ok.  But I did not get a vacuum carb, oh no, I just got 3.91 gears in back.

[Ghoste]

Then again, for 100 bucks, it might be a good one to pick up in case you decide to add more gear or anything later on.  Your cam will appreciate headers and more gear too.

[Headrope]

Headers - or at least HP manifolds - and a taller gear are planned for the future. I'm figuring a $350 plus carb (new) for $150 (cost of this used one plus a rebuild kit that may-or-may-not be needed) is a good deal.
I'd like a carb I can use in the meantime, though.
Ugh. Decisions decisions.

[dodge freak]

Then get it, it has the fuel line too thats nice. As long as you will get better gears later why not . I did the samething. I like the proform main body but you can get that later also. The base plate is worth at least $50.00  so It is a good buy and it does not look to old. You can also disconeck the secondary and drive it that way while you adjust the primary's.  You can always get you money back on e-bay. Those carbs. get bid on alot I  have seen.

[Ghoste]

Looks like it has a regulator on there too.  Does that come with it as well?

[Headrope]

Yep.

[jg68]

Yep.

I would look at the #s on that carb, looks like maybe a 4777 650 DP, if i'm not mistaken, all factory 4779s came with down-leg boosters, those boosters are straight!