Double Pumper On The Street Or Not?

[Moparman01]

I recently bought a Holley 750 double pumper from a buddy of mine and had it professionally rebuilt specifically for my 440 in the General by a another good friend of mine who is a local racer and all around carb/tuning wiz. He wants me to get rid of the 750 Edelbrock currently on the engine for the DP, says it will wake the motor up considerably. Well, I was going thru the last issue of Mopar Action and they said running a double pumper carb on the street is a big no no. They say they will wash the rings/cylinder walls and dilute the oil due to the extra fuel on a strictly street engine. So I'm wondering if I should bother with the swap? My engine is a mild build that made 449hp and 480tq on the dyno when it was built. My buddy says he will precisely tune the carb for all around driveability and that I will be much happeir with it over the Eddy. So, to swap or not to swap, that is the question!

[XH29N0G]

My guess is that the washing of rings is an overstatement, but I'll wait to see what others say.  As you are undoubtedly aware, the second accelerator pump is there to allow the secondaries to be opened more quickly, and this can make a difference if properly set up.  It took me a while to dial in the double pumper I have, but it has instantaneous throttle response and pulls very well, the car idles and cruises just as it should.  It can/will affect gas mileage but not too crazy (I get about 8-10 mpg on average - but don't baby it).  It also may depend on the gearing of your car, which I assume will be fine, but if you have 2.76, I would ask.  From the sound of it, it seems to me that your engine is well set up for this carb.

[RECHRGD]

I've been running one for over 15 years on mine and love it.  Absolutely no problems on the street or highway....

[c00nhunterjoe]

I love double pumpers. Never had a problem on the street all the way up to dominators.

[Brass]

The old "no double pumpers behind automatics or on the street" fallacy.  I wish it would die already, and a pox upon Mopar Action for perpetuating it.  

[flyinlow]

The old “no double pumpers behind automatics or on the street” fallacy.  I wish it would die already, and a pox upon Mopar Action for perpetuating it. 

It's not just them. Holley and Quickfuel say the same thing.

[Brass]

The old "no double pumpers behind automatics or on the street" fallacy.  I wish it would die already, and a pox upon Mopar Action for perpetuating it.  

It's not just them. Holley and Quickfuel say the same thing.

Weird.  Then they're pigeonholing their own product.  To the OP: like any other component, the combination should be considered.  Double-pumpers may indeed perform better with some stall or gearing but I don't understand the absolute declaration that they should not be used on the street.  That runs contrary to all evidence I have seen.  Based on what you describe, it sounds like your friends know what they're doing.  I would give it a try.  If you don't like it you can always go back to the Edelbrock.  But I think you're more likely to be back on here proselytizing the godly virtues of mechanical secondary accelerator pumps.  In either case, good luck with what you decide.

[c00nhunterjoe]

They say that because 90% of people dont know what a carb is, let alone be able to tune one. So it eliminates returns on a product that is unwarrented.

How many posts on here start out with "brand new piece of crap holley bogs"?

[6spd68]

I have to agree with everyone, and endorse the use of the double pumper.    You'll notice a day and night difference between the Holley and your Eddy.  I've ran the same Holley 650 double pumper on both a (SBF + World Class T5) & (SBC + TH350), performed WAY better than the Eddy I tried on the SBC.  On the SBF, I moved up to a Holley 750 Vacuum Secondary, with a dual plane intake, and it loved it even more.

I'm rather confident your 440 will wake right up with that carb.  What intake are you running?

[flyinlow]

A Holley DP is like having two midgets with super soakers filled with gasoline sitting on top of your engine waiting to drown it with fuel. Does it work...yea sometimes really well.

So you are sitting on the concrete starting line at the drag strip with M&H race masters that your engine can not even chirp. Light turns green and you mat the 750DP. Both accelerator pump discharge and all four bores are wide open, You have a stock converter and a 3.55 axle. The engine jumps to 3000 rpm and as the car starts forward the rpms start to climb. At 3000-4500 rpm you are way over carbed. Low velocity thru the bores = bad fuel metering.
Can the engine climb to enough rpm's before pump discharge "burns off" and the engine can use 750CFM?   sometimes.

The identical Charger beside you has a well tuned 750(VS) .He launches on the primaries and the secondary's come in about half way thru first gear with the engine properly carbed the whole way... he beats you to 60 feet and stays that same distance in front to the finish line.

Now if you have street tires ,that spin and let the engine rev up quickly, or a lower gear , or a high stall converter, or you slip the clutch or you do not mat it and feed the throttle in as the engine can take the DP may work well for you. Try it.

[Moparman01]

Thanks for the replies! My 440 has Edelbrock Performer heads and a Performer RPM intake, and I curently run a 750 Eddy carb, and yes I still run a set of HP manifolds instead of headers. I have a manual valve body 727 with a 2500 stall, and 3.55 SureGrip out back. Not the craziest set-up, but he'll go sideways on comand with out much trouble. The Edelbrock carb runs ok, but has the typical off idle surge and does bog a little bit at the hit of the throttle. My buddy who built the Holley DP says the throttle response will be much sharper, and all around driveability will be better.

[Nickrc3]

Moparman01, save yourself the grief and replace your Carter with a Holley (or equivalent) DP carburetor. I had the stock AVS installed. After ordering and studying two books on these carbs, a thorough rebuild, several pump adjustments and swapping different fuel rods, could never get it to perform adequately - rough idle, inconsistent starts, constant bog under hard acceleration, etc.
Took Ron's advise and installed a Proform 750 DP w/ CH6B manifold. Wow - talk about waking up the motor! From a complete stop, once the accelerator pedal is mashed, its just an angry sounding engine, spinning tires into 3rd Gear. She does miss a beat!

So, the original car w/manifold is well-oiled and stored in a bag, where she'll stay.

Good Luck.

[69wannabe]

Double pumper carbs are pretty much it for me on any mopar. I have tried at least 5 or 6 different carb's on my charger from a carter,3 edelbrocks, a 600 holley and a 670 street avenger when I finally got my hands on a 750 holley double pumper and man did that open my eye's!!! The double pumper carbs are the best IMO.....

[charger_fan_4ever]

Thanks for the replies! My 440 has Edelbrock Performer heads and a Performer RPM intake, and I curently run a 750 Eddy carb, and yes I still run a set of HP manifolds instead of headers.

With an edelbrock top end its being choked to death with that edelbrock. They are a good truck carb thats about it. A proform carb with the HP style center section be right at home and i wouldnt be surprised if you picked up atleast 20hp at the tire doing the swap.