I've had my holley 750VS for years and it's all tuned.
Recently it doesn't want to open up on the top end all the way. I replaced the secondary vacum diaphram and sprayed some carb cleaner through the hole and could see it coming out in the bores. So I don't get it's problem.
So now it's making me mad I was thinking 750 DP, but the thought of re-jetting, getting the bigger accel pumps, cams and squirters to make it run optimal is making me lazy.
Anyone go to a DP from a VS and regret it?

 

my 305 went from 13.7x's to 13.2x's just by switching from a 600vs to a 600dp. i then bought a 650 main body and built an air pan to seal the hood with the carb and put a set of underdrive pulleys on it, car went 13.0's.

managed to maintain the same mpg as well, as long as i kept my foot out of the loud pedal.

the 360 i have now i went ahead and upgraded to a 750 main body and throttle blade plate and i've still maintained just 1mpg less than my old 305...and i've already gone .9 faster with more tuning to be had.

 

hymm i am thinking about going from a 650 VS edelbrock to a holley DP, i hear they are completly different, i know pricewise they are...

 

I tossed the CC qjet and distributor on a built 355 in my sport coupe for a 750dp and I will NEVER look back...way more responsive, free revving and just an all round happier engine. Mechanical secondaries is where its at, no wating on vacuum to open the blades...as for everyday driving and mpg, a lot of guys on here are q-jet worshippers and badmouth holleys for being the best carbs period. Tune it properly, get a good manifold and be done with induction!

 

On the 396:

750 VS to 650 DP - gained 2 tenths, mostly in the 60'.

650 DP to Proform 750 mainbody - gained another tenth.

Very happy.

 

Thanks for the info so far let me ask another question.
On my 750VS I had to upgrade to the bigger 50cc accel pump, biggest pump cam and bigger squiters so it didn't bog when i stood on it from a stop(400 likes it gas)
Think I should pretty much count on having to upgrade both pumps, cam's and squirters here or being two will I get away with the stock 30cc's.

 

i've got no issues with the stock 30cc's as well as stock pump cams. i'm also running a size 31 squirter front to back.

 

Other than swapping PV's, changning jets, and fine tuning idle mixtures, with all 7 holley's I've never had any issues with factory cams, pumps, or squirters. I obviously never had the carb tuned to 110% effiecency, but I never had any headaches either, botl it on, intial checks then run it till the weather takes a drastic change and swap jets.

smallest on track gain I've ever seen doing the Vs to DP switch is .3

you will not regret the descion and you'll slap yourself for ever running a VS on a car you wanted to go fast Leave the edelbrocks and VS to car shows and grocery getters.

 

well i havent put on a DP yet but right now i have a Demon 850 VS and when i had it dyno'ed at layed down 335HP/365TQ to the wheels with my built 383. The air fuel mixture was off and the guy at the shop said the motor is leaning out and i need a 850 DP from Proform or Quickfuel. My car is a high 10 sec car and he has seen what i done on the street and knows my car has WAY MORE potential of getting better numbers. So until i save around $550 im gonna have to stick with my 850 VS Demon..............

 

I wouldn't call myself a Q-jet [I]worshiper[I]

I think they are great for a street carb, and I do like the economy of the small primaries.

However, I wouldn't mind borrowing a DP to see what it would do on the track, seeing the results all get with them. It's pretty much a closed case, they are more responsive than any vaccum secondary type of carb.

 

you have a high 10Sec car with 335 HP? how much does your car weigh?? What other things have you done to get the car down to high 10 sec with 335hp at the wheels?

 

Do you guys use 1 or 2 PV's on your DP?
My VS is tuned perfectly so I am trying to get as close to possible right off the bat. I run 68/78 jets but if the secondaries now had another PV I guess I should run smaller ones.
Thinking I'll stick the 50cc and red cam in the front for now and 30cc in back.

 

Aaron, if you do alot of street driving go ahead and run a rear PV since it will help with streetablity and not wanting to load up quite as bad. Step down 6 jets and see where your at. Typically with race cars they remove both PV's and just jet up 6-10 sizes to compensate, removing the PV's helps in the consistencey department but is very finikey with typical street driving with both removed....wants to load up quite bad.

I removed my rear PV early last year and noticed a better repeat on the slips and on the street it was tolerable since most of the time I "cleaned it out" often enough it never became a problem

Either way I hope your buying a new carb so you dont put yourself into the same boat as most others buying a used one and having constant problems. Run it out of the box and tune from there as far as jets, if you already know what PV to use you'll have to install them before driving to make life easier. Before removing the PV's I was typically only 2 number apart front/rear, now without PV I'm 6 numbers different. Bigger carbs will need bigger jets, so dont get all weirded out when you start increasing them to make it run right, set some time soon when you get the new DP to track tune for best mph...keep increasing jets by 2 numbers until it slows a bit, then back off 1 and see how it runs. If your doing it right now the still cool spring air will make you pretty fat during the hot humid summer so round june/july back off a few and your plugs will like you for it , then go back up this fall.

 

My car weighs 3300lbs and should easily be a mid to high 10 sec with slicks. I know street racing isnt good but i ran against a EVO from San Fran with 420 AWD HP and beat him. He showed us his 11.3 time slip and like i said i beat him by like to cars and that was with my street tires!! i wasnt catching traction till 3rd. Also my uncle has an 03 ZO6 with a magnus supercharger and we were neck to neck until past 140mph then he pulled of course.
Anyways i got a 383 stroker with 850cfm Demon VS, Edelbrock RPM Air gap, 1.6 Crane Aluminum RR, AFR 195cc heads, Lunati custom .600 lift cam, all MSD ignition, Headman headers, custom 3" exhaust, all to a professionally built 700r4 with 3500stall to a torsen posi with 3.73's

So the car does **** and get and with the vaccum secondaries not opening up thats why the numbers were what they were. The guy said if i change to a DP (which engine needs anyways because it seems a little lean) then the numbers would be a whole different story.