I would not use a power valve in the rear for a drag carb.Hard accelaration may let the power valve ports suck air making the jet extensions just about useless.Bill.

You should buy a bigger fuel pump! That can handle the demand of a high horse power application because it's about volume not pressure ! ( In saying that!) under a hard accleration with a good fuel pump that fills the demands of the bowls trying to empty out, that should never happen due to the fact that the bowls are at negitive pressure under acceleration the in coming fuel should fill bowls faster with the right fuel volume and pressure with a good high flow regulator with a properly set float adjustment and high flow needle and seats! There for the pv holes and and jet extensions should stay completely covered all the time good luck joe g 8)

Look at a metering block with a power valve.The power valve will be the first thing to get air when the fuel is forced to the rear.If thats not the case everyone could quit wasting money on notched floats&extensions.Just my opinion.Bill.

in the 60's before jet extension and notched floats what did the holley carb guru's do then ? holley does make proformance carbs don't they when you get it out of the box, do they come with jet extension and notched floats? I think the reserch and devolpment that they do weigh's heavy on what they sell the public, (maybe) just my thought on this situation joe g :)

Holley's ultra carbs come with a notched float instaled in the rear and extensions in the box.The power valve feeds to the main well are lowered to help keep them in the fuel.So just maybe even the big names can learn from us racers.For drag use remove the rear power valve,install the extensions and go up 6 to 8 jet sizes.The aluminum ultra is one of the best race carbs you will find and very adjustable.Bill.

Y'kno, for years, Holley's line of double Pumpers and then the Dominator series were the "Go To" when racing with just about any engine . . And, over that period of time, many racers learned to "Tune" Holley's by hook and by crook . .

Thus . . The only thing worse than a used Holley, is two used Holleys . .

Last year, I was introduced to a "New" Carb. The Pro Systems SV-1 . . We bolted one on a 496 BBC and ran it . . no dicking with it, nada, outa the box. 96 pills "square". It was "Slightly rich" but no blubber or smoggy plugs, beautiful tan insulators, one ring of heat on the plug thread . . Great, and a "Happy Motor" . . .

Had a problem with H2O in the oil, put in a 468 BBC with Dart 355 heads, never touced the carb, just bolted it on and went . .

Back to the 496 with the Dart heads on it, again, just bolt it on and run it . . Plugs look great, 1125° EGT, and now, we're running a 582, same heads, and still haven't done anything to the carb but adjust the idle air screws. same jets, same everything, just like it came out of the box . .

9.38's at 149-150 in 8500' corrected air, 2800# Iron 67 Camaro . . not to mention we've raced at 4800', 5000' and 6000' MSL and, again, never touched it . . And the motor's still "Happy" . .

It's a good piece of hardware that literally "self compensates" by working to the amount of air going through it . . .

Roadkill,I looked at that carb when I first heard of them.Looked trick but scared me.You are the only one I've heard give first hand info about one.Sounds like it did a good job for you on several motors.Bill.

Do not ever run a PV in the rear of a drag carb, there is absolutely no reason to run one there and plenty not to. A faster car can uncover the PVCR's and lean the mixture. On a trans brake equipped engine I don't run one in the front either, if the idle and transition metering are correct you really don't need it there either.

And then there are pretty carbs...

http://i287.photobucket.com/albums/l...2300LRCFX2.jpg

http://i287.photobucket.com/albums/l...Hybrid1050.jpg

http://i287.photobucket.com/albums/l...LRC145x175.jpg

http://i287.photobucket.com/albums/l...arbTrophy2.jpg