Double plumper carb or stay with Vac sec carb?

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moparmatt19

moparmatt19

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ok spec on setup. 360 .030 kb pistons 10.2to1 comp. run 93/110 oct 50/50 mix J heads ported with 2.02/1.60 hughes engines cam HTL4852s solid cam. 248 252 @ .050 .563/.572 106 lsa. air gap intake,Hooker super comp headers, carter race mec. fuel pump, holley street avenger 770 carb , pertonics flame thrower 3 bilet dizzy with rev limiter set at 6800 , TF727 race built with 3500 stall, 3.92 sure grip 28/10.5/15 MT slicks.
Question is would I gain by going to a double plumper carb on this setup? Other notes for the future is that I might be going to a M1 single plane intake and prob a set of 4.30 gears. for now it is drove on the street but will be soon a race only setup and maybe a cruise on the weekends. Engine is in a 67 notch cuda race weight 3300 lbs. What Ya think? Thanks in advance!
 
Yea to the double pumper. I'm not so sure about the M1 over the AG though. It is a great intake, but the loss of low end torque, yes, even at 3500 May make you slower.
 
Double plumper? So you mean a muffin top with an extra layer on top?
LOL, sorry I couldn't resist...
 
Run a double pumper.

Do you know which spring is in the vac carb now? If it's a stiff one, the secondaries may not be opening all the way.

I'm not a fan of holley vac carbs on much of anything.
 
I just laugh my butt off lol. I just noticed the double plumper. ... stupid phone auto correct!! Well anyways I think I want to go with one. I have the lightest spring in my secondary now. Sometimes it seems like the secondary should come in a little quicker on it and figured if I just went with a mechanical secondary. Carb I would have to worry about that anymore. And I think the MS carb would be more consistent
 
Stay with the airgap & switch to a DP Holley. I run a 700dp on mine for the street. Seems a little smoother. Have also run a 750 on it and it worked great. Just got to tune them in.
 
Use a QF adjustable vacuum on the secondaries. You can make it just about the same as a double pumper with much better street manners. Although I have a DP on my 410", if I had to do it again, I would go with a QF vac secondaries.
 
Yes, the dp will be faster, especially if you are leaning toward a race setup (which it sounds like you are). I would stick with the Air-gap for now, the M1 would probably be a step backward with that setup.
 
If your vacuum secondary carb works fine and is tuned, there's no reason to change. Use lightest
spring. By the time your converter is flashing 3500, your secondaries will probably be 1/2 way open
and be fully open within another 500 rpm.
 
I run a 650 thunder series on my 360 on the street and it runs great. I put my Holley 750 dp on for the track though. The dp gave me four more
Mph on the track.
 
Tantibus-74 said:
Double plumper? So you mean a muffin top with an extra layer on top? LOL, sorry I couldn't resist...
Click to expand...

Dude you beat me to the smarta$$ reply! LMAO!Was going to ask if he was deciding between a skinny girl or plump one! Remember the saying a$$ or grass nobody rides fr free? LOL!
 
I've made vacuum secondary carbs work well in your situation, it just took time & tinkering to get there.....Looks like a 750HP would be the most cost effective carb for a upgrade?

If you really want to make some hey at the racetrack, do the carb, the gears, the M1, and talk to a good converter builder to build you a nice 9.5" that will give you some serious 60' capability and still be streetable on a limited around town basis...
 
Double pumper,leave the air gap,try a 1" open spacer.(my.02). If becoming a track time car of any sort, start a log journal. Every pass,every change,record the results in that log journal. That will remind you of what works,and not doing it twice. Log rpm shift changes/launches,timing/carburetor, & combination changes.That way,you don't do the same thing twice. Fwiw,Rick's 9.5 converter idea,food for thought. Good luck.
 
double pumper will give you gains at the track

but it will be cold blooded. sec vac street carbs work better in cold weather.

once you get them running and warmed up they are fine on cold days tho
 
moparlover said:
double pumper will give you gains at the trackbut it will be cold blooded. sec vac street carbs work better in cold weather.once you get them running and warmed up they are fine on cold days tho
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This doesn't neven make sense....

The 4 bbl opening method have nothing to do with it's warmup process or cold weather operation.
 
Don't think anyone was talking about the HP series. Car would definitely pickup with that style. I live in the north and haven't used a choke in 20 years or more. Just got to keep your foot on the gas a little till it warms up. No big deal.
 
roccodart440 said:
This doesn't neven make sense....

The 4 bbl opening method have nothing to do with it's warmup process or cold weather operation.
Click to expand...

I didn't take it that way. I think it was (from my point of view at least, the way I understood it) more on how the secondary side would open up to fast or unwated- ly during weather & engine being to cold for good operation.

moparlover said:
here maybe this makes sense rocco

Holley 4150 hp carburetors have NO choke tower
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I did not even consider that carb. He said double pumped and I just thought of a regular 4150DP that has a choke. Electric or manual.

To the OP, the best thing about a DP carb is YOU control the secondary opening. The metering block is better than the plate.
 
80fbody said:
Don't think anyone was talking about the HP series. Car would definitely pickup with that style. I live in the north and haven't used a choke in 20 years or more. Just got to keep your foot on the gas a little till it warms up. No big deal.
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yes /\ /\ /\

In addition I run a 4150hp. I run it in the 30's this time of year. about 60 seconds of warm up until it idles and then a little warm up time. In regards to the 4 barrel activation I don't use my 4 barrels when the engine is ice cold and it's easy to feel when they will engage.
 
I have always had a performance gain when switching from a vac secondary to a double pumper. I will say however that I have seen some stock eliminator cars with vacuum secondary carbs that were very fast and run super good. They were so good in fact that I would say they were like a raped ape and a scolded cat had mated and created some new freakshow life form. Vacuum secondary carbs have the same power potential as double pumpers. They are more dificult to tune to where you can do that idling in gear and smash the gas pedal to the floorboard and have the engine suddenly rip with no bog thing. Go on YouTube and see my channel. Same name as on here Doosterfy. You will see at the track I leave off dead idle and the car just lights up and GOES! 20 initial timing and a double pumper is how mine works. You would see similar results. An engineike yours would do good with a 750 or 800 carb.as far as the intake I would see if you can borrow a single plane from someone to try it before shelling out the cash. I bet you will like your dual plane better.
 
I think I'm going to get a 750 4150HP. And try it out after I get m other issues I'm having figured out. But should I get a Holley or go with a quick fuel? I've heard quick fuel is Chinese junk and I've heard they are the best? Anyone used both brands? Likes or dislikes?
 
Oh and I don't care about a choke. I don't mind to set and peddle it for a few mins to warm up. And it soon will be a track only engine aanyways
 
moparmatt19 said:
I think I'm going to get a 750 4150HP. And try it out after I get m other issues I'm having figured out. But should I get a Holley or go with a quick fuel? I've heard quick fuel is Chinese junk and I've heard they are the best? Anyone used both brands? Likes or dislikes?
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Have a Q.F 750 double pumper on my 360 Magnum. Huge difference between it and the older Holley 4779 double pumper. Crisper response,off the bat. My .02, decent equipment.
 
moparmatt19 said:
I think I'm going to get a 750 4150HP. And try it out after I get m other issues I'm having figured out. But should I get a Holley or go with a quick fuel? I've heard quick fuel is Chinese junk and I've heard they are the best? Anyone used both brands? Likes or dislikes?
Click to expand...

I've used the Holley, Demon and Proform

In order: Holley, Proform, would never buy another demon.
 
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