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Holley Ultra HP950 dilema
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Author:  traysvega [ Mon Apr 16, 2012 7:08 pm ]
Post subject:  Holley Ultra HP950 dilema

Sup everyone.Well after the car sitting for almost 2 years I've dusted off the cobwebs and hit the track only to have issues.Long story short I ended up with a brand new in the box 950 ultra hp.Popped a bowl off and to my disbelief I see 92 jets (squared) plus a power valve(front and rear)...Im thinking jeez somethings wrong here.Holleys web site no specs on what comes in an ultra.I installed 86 square with no power valves(block offs) and went friday to the test and tune.Car ran horrible.Everything was off 60 ,330 660...etc labored and sputtered(not a backfire)(more like a miss) 6.66 and then a 6.73 in the 1/8@ 101.53....Went back and installed the power valves that came with the carb.Better but still sputtering 6.57@ 105.47 and 10.28 @ 132.33.Still way off the normal(e.t mostly ....should have easily run 6.20's and 9.70,s 80's.
So heres the interseting part.I called holley today.They guy told me that the carb HAD to have 92 square plus or minus 4 jets sizes PLUS the power valves or add 6 sizes to the 92 jets...Just doesnt seem possible....it would need thast large of jetting plus power valves adding to it....Any ideas ,,,Im just about to give up....Oh I did a flow test today on the pump 1 gal of fuel in 20 seconds...any help appreciated..Thanks guys

Author:  2BadCat [ Mon Apr 16, 2012 7:33 pm ]
Post subject:  Re: Holley Ultra HP950 dilema

Interesting thread. My suggestion would be to contact Nomad [Bruce G.] on this board and talk to him about the Ultra Dominator. He has had some experience with them.
Is the carb running REALLY lean ? I just got a 1100 from an internet friend on another board. Slapped it on my Catalina, went to an 1/8 mile track. LOST almost a full second and the Air/Fuel was almost 16 to 1 !!! Ran like the car was stuck in mud with no power once out of the hole. My 1100 was set up at factory with 97 jets square and 6.5 power valves front and rear. Like yourself, I scratched my head over that. I posted my dilemma over on Yellow Bullet and Nomad from this board answered and suggested a new tune for my carb. I just now finished installing the new tune and hope to test it out this Thursday evening. Not being a carb expert I don't know if the new tune would work in your combo or not. I'm running a 495 Pontiac stroker in a two ton car so your combo might need something different. In a nutshell and since the carb was so lean Nomad suggested I put in smaller emulsion bleeds and air restictor in the metering block. He also suggested plugs in two of the emusion bleed positions.
I'm going to try it with power valve plugs front and back. Anxious to see how it works now. BTW: In my Yellow Bullet post there were some guys that answered they were having the same problem with their Ultra Dominators, ie running real lean.
Good luck and I'll post the results of the new carb tune.

Jim

Author:  jmarkaudio [ Mon Apr 16, 2012 7:33 pm ]
Post subject:  Re: Holley Ultra HP950 dilema

The larger venturi used by the new 950 kills booster signal, you have to use a larger jet to make up for it. That carb might do well on a larger BBC, anything smaller and I'd rather see annular boosters in it. Frankly I think a 1050 is a better choice.

Author:  traysvega [ Mon Apr 16, 2012 7:48 pm ]
Post subject:  Re: Holley Ultra HP950 dilema

Thanks for the replies..Mark,I asked that also to the holley tech and he stated it would work fine for my appMe think no now lol)...What you mentioned AFTER talkin to him was my thoughts also...Guess I should have done alittle more home work before purchase..He did also however mention that I should at least use a 4 hole spacer to help with the signal.Or no spacer at all(which really isnt an option at this point).

Author:  Slowpoke [ Mon Apr 16, 2012 8:56 pm ]
Post subject:  Re: Holley Ultra HP950 dilema

I would try it like it came out of the box and tune from there. Holleys are usually in the ballpark from the factory.

Author:  traysvega [ Tue Apr 17, 2012 6:46 am ]
Post subject:  Re: Holley Ultra HP950 dilema

Yep Donee,the 92 pills plus the power valves are back in..we shall see...and I also got an allstar hvh type 4 hole spacer to put on plus a set of spark plugs.

Author:  Shaker455 [ Fri Apr 20, 2012 5:13 pm ]
Post subject:  Re: Holley Ultra HP950 dilema

traysvega wrote:
Sup everyone.Well after the car sitting for almost 2 years I've dusted off the cobwebs and hit the track only to have issues.Long story short I ended up with a brand new in the box 950 ultra hp.Popped a bowl off and to my disbelief I see 92 jets (squared) plus a power valve(front and rear)...Im thinking jeez somethings wrong here.Holleys web site no specs on what comes in an ultra.I installed 86 square with no power valves(block offs) and went friday to the test and tune.Car ran horrible.Everything was off 60 ,330 660...etc labored and sputtered(not a backfire)(more like a miss) 6.66 and then a 6.73 in the 1/8@ 101.53....Went back and installed the power valves that came with the carb.Better but still sputtering 6.57@ 105.47 and 10.28 @ 132.33.Still way off the normal(e.t mostly ....should have easily run 6.20's and 9.70,s 80's.
So heres the interseting part.I called holley today.They guy told me that the carb HAD to have 92 square plus or minus 4 jets sizes PLUS the power valves or add 6 sizes to the 92 jets...Just doesnt seem possible....it would need thast large of jetting plus power valves adding to it....Any ideas ,,,Im just about to give up....Oh I did a flow test today on the pump 1 gal of fuel in 20 seconds...any help appreciated..Thanks guys


I have the very same carb here that a customer sent me for calibration before fire up on his new street combo.

I would disreguard the Holley tech as every combo has different requirements and the factory 92 square with 4.5 square PV's was a bit fat.

In this case this is the first true 950 from Holley as I measured the venturi and it is 1.600" so that about .038" larger than the 850 that is 1.562" (1-9/16")

The new all aluminum Ultra Hp Holley 950 is about the same size as the Race Demon Silver sleeves so jetting is going to be slightly more than a 850.

I don't know your engine combo but if you post it I can get you to a staring point.

I'm running a Pontiac 455 and I started off simply by colsing down the bypass air valve in the center of the carb and used 82/90 jets and removed the rear factory 4.5" Powervalve to start.

I dialed in all the mix screws evenly and it runs nice.

First test ride during heavy part throttle I seen a slight lean spike on my wideband so I may tame that with either jet,squiter,or a 50cc pump in the front.

Also it comes with .032" hi-speed airbleeds so if your drag racing I would suggest dropping down to .025's

Author:  Eric68 [ Mon May 21, 2012 7:38 pm ]
Post subject:  Re: Holley Ultra HP950 dilema

Just FYI -- on my flow bench with a high flow base plate the new Ultra 950 (lighter aluminum) body flowed 965 cfm. The venturi size is a hair bigger than the old HP 1000 (I measured 1.626-1.627" Shaker 455 -- guessing its supposed to be 1.625 or 1-5/8"?). IMO this carb is good on engines that are roughly 550-650 HP although I don't know about the Holley gas tuneups at all (I build 'em for E85)

The old diecast zinc (green colored and heavy) HP950 has a much smaller venturi and only flows right about 830 cfm on my flowbench. This carb is good on engines roughly 400-500 HP.

Stick with the Holley tuneup to start, you may have to jet it higher than the Holley out-of-the-box tune because it is a little big for your combo.

Hope that helps a little.

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