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  #1  
Old Aug 3rd, 09, 9:28 PM
adeeos adeeos is offline
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Default 950 HP jet size for street

What are you guys running for jets in your 950 hp for street strip? I have 80's in the front and 89's in the rear with factory power valves front and rear. I am killing plugs and it is pig rich.

I have run my best ever et with these, but it is not worth l
killing the plugs. I am running NGK R5671-7's on the street and spray a 200 shot with NGK R5671-8 on the bottle.

Dart Pro 1 325's on a pumnp gas 462 if it matters.

Thanks!
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  #2  
Old Aug 3rd, 09, 9:40 PM
69shovel&90454SS 69shovel&90454SS is offline
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Default Re: 950 HP jet size for street

Way too rich in the rear with a power valve.
Block the power valve in the rear or change the jets to 82.
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  #3  
Old Aug 3rd, 09, 9:46 PM
yenkomike yenkomike is offline
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Default Re: 950 HP jet size for street

i dont know what cam your running but that might be why your fouling plugs if the power valves are open while your cruising. i run 77 primary jets with a 3.5 power valve. and 86 secondary with no power valve and my plugs are last years. i think you'll need to be around 76 to 77 jets to run clean. and if you have very much cam the power valve is the big problem stock ones are 6.5 .hope this helps
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  #4  
Old Aug 3rd, 09, 9:53 PM
adeeos adeeos is offline
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Default Re: 950 HP jet size for street

Here are cam specs: Crane mechanical flat tappit,

638/659 lift
242/272 duration.
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1972 SS Chevelle sold
1955 Chevy 454
1970 GTO 455 rag top
1965 Biscayne 4100 lbs
New 598-first time out:
1/8 7.20 @ 96.74
1/4 11.20 @ 118.79
Let the tuning begin
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  #5  
Old Aug 3rd, 09, 11:41 PM
dirtlips408 dirtlips408 is offline
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Default Re: 950 HP jet size for street

I was running 76/86 in mine with a blocked rear p/v.
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  #6  
Old Aug 3rd, 09, 11:51 PM
wade w wade w is offline
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Default Re: 950 HP jet size for street

If you have a power valve in the front and the rear. The jets should be about the same size. The jetting you have should be right for just a power valve in the front and the back one blocked off.
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  #7  
Old Aug 4th, 09, 5:57 AM
ericrickster ericrickster is offline
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Default Re: 950 HP jet size for street

in summer air and especially street driving i can't see why the stock 78 square jetting wouldnt work for you

btw,your power valve size should be 50% of the vacuum at idle reading.

the way it's jetted now for racing doesn't seem right even though you've have your best times with it

could be a weak fuel system for you to have to use that much jet,kind of just a band-aid
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  #8  
Old Aug 4th, 09, 6:45 AM
Bob West Bob West is offline
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Default Re: 950 HP jet size for street

You're a long way from 78 sq. jetting. I dont know how it runs. I think I ran 78-80/86-88's with no rear power valve.
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  #9  
Old Aug 4th, 09, 6:50 AM
adeeos adeeos is offline
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Default Re: 950 HP jet size for street

Thanks for the replys guys. I will check the size the the P/V's tonight and likely plug the rear as suggested and reduce the jet sizes. As far as fuel is concerned, I run a Manga Fuel 500 pump and filter
-10 line to the reg and two -6's to the carb.

I'd like to run True Street near here at Z-Max on Saturday and I do not want to fowl plugs on the cruise.
__________________
1972 SS Chevelle sold
1955 Chevy 454
1970 GTO 455 rag top
1965 Biscayne 4100 lbs
New 598-first time out:
1/8 7.20 @ 96.74
1/4 11.20 @ 118.79
Let the tuning begin
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  #10  
Old Aug 4th, 09, 7:00 AM
SPARK69 SPARK69 is offline
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Default Re: 950 HP jet size for street

80/84-86 is fine
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  #11  
Old Aug 4th, 09, 7:02 AM
69-CHVL 69-CHVL is offline
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Default Re: 950 HP jet size for street

I had 2 Holley 950HP's, both ran phenomenal, but very rich at cruise. They ran something like 10.8 AFR. I tried everything in the world to lean it out, and all it did was screw-up the throttle response. Ended up with a Prosystems 950HP that ran like the Holley but gave a cleaner cruise.

Is yours newer or older?
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  #12  
Old Aug 4th, 09, 7:38 AM
creeper72 creeper72 is offline
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Default Re: 950 HP jet size for street

Quote:
Originally Posted by Bob West View Post
You're a long way from 78 sq. jetting. I dont know how it runs. I think I ran 78-80/86-88's with no rear power valve.

Bob's advice is prob a great start.
Just for reference - I run 85/90 with rear pv blocked , this is where it flowed best @ the carb shop on a bench .It seems a little rich still. I think Bobs #'s are real cose to where I will end up.
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  #13  
Old Aug 4th, 09, 8:55 AM
40Coupe 40Coupe is offline
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Default Re: 950 HP jet size for street

The richest I ever ran with the HP 950 was 80/88 with the rear PV plugged in less than 1000' DA.
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  #14  
Old Aug 4th, 09, 10:07 AM
GRN69CHV GRN69CHV is offline
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Default Re: 950 HP jet size for street

JMHO, the Dart Pro One heads have terrible low RPM response. Flow great at higher RPM / higher CFM demands, but poor at cruise. Went through the same thing. You run 325's on a 462" motor, I run 310's on a 469" motor. Kept jetting up to get it to cruise, them went fat at WOT. Switched to a BG 800 annular. Completely different motor with the annular. Not advocating it, just stating a personal experience. Only carb that I had that was close was the 750HP street which is really the 950HP with the smaller baseplate and street jetting. I would try a smaller carb w/ down legs or an annular booster carb.
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  #15  
Old Aug 4th, 09, 8:39 PM
SS_Sean SS_Sean is offline
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Default Re: 950 HP jet size for street

Quote:
Originally Posted by adeeos View Post
What are you guys running for jets in your 950 hp for street strip? I have 80's in the front and 89's in the rear with factory power valves front and rear. I am killing plugs and it is pig rich.

I have run my best ever et with these, but it is not worth l
killing the plugs. I am running NGK R5671-7's on the street and spray a 200 shot with NGK R5671-8 on the bottle.

Dart Pro 1 325's on a pumnp gas 462 if it matters.

Thanks!
I had 82 front/87 rear's in mine, with PV plugs. And that is with a car that was running a 10.57@125 mph at the time. I can assure you, you are pig rich.
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