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Discussion Starter · #1 ·
Hey all, I have a holley 950 hp carb on my 355 sbc. I just started racing after some time off and could use some help.The carb has power valves in the front and rear but I heard of some people just blocking off the rear power valve and upping the jetting in the rear. The combo is a 12/1 355 with a 630 nitrous roller aluminum heads,2055 intake and 160 exhaust,team g intake and the 950 carb. The jetting is 78 fronts and 82 in the rears with a front 3.5 power valve,the rear power valve im not sure of off the top of my head,i gotta check.
One run I shut it off to check a plug and the plug was white and I wanted to get some opions before I run it again. Timing was at 38 total. Thanks for the help.
Greg
 

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Discussion Starter · #2 ·
Also running AR 3924 plugs gapped at 30 and fuel pressure is 7 1/4 at idle and 6 psi going through the traps. Also looking into a EGT gauge to help me with the jetting. And info on a good product to buy. Thanks Greg
 

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I ran a holley 1000HP last year with good results, not sure how close they are to the 950HP, but assuming they are. I had power valves front and rear and used 88 jets front and rear. Probably go to a 84-86 square with the 950. Have to be careful where you're seeing the white. If you read on here the best way to tell is to cut the plug and look on the curve of the porcelin for a light grey line. If you're just running it N/A I'd go to a 3934 plug, 3924 is too hot of a plug. Timing might be close, but look at the strap for your timing line.
 

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Skip the EGT and get a dual O2 like an Innovate system. Yours should have come 78 square with power valves, but I do not recommend power valves on the rear. You have no extensions on the PVCR's and can be uncovered on launch. Try 80 front and 88 rear without the rear power valve and see if the MPH picks up or slows down. If it slows, go back down a little at a time, if it pick up try going up more.
 

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Discussion Starter · #5 ·
Thanks for the info guys. As of now Im just running her on motor but I do have a fogger on it and I want to see how fast I can run on the motor alone. I will try what you guys said hopefully next sunday with the new plugs and the jetting.If you have any more info please pass it on.

Thanks!!!
Greg
 

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Does anyone have a part number for the item to block off the rear power valve on the 950hp. I was on holleys site and didnt see one. Thanks,Greg

Holley 26-36

Tom
 

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Hey all, I have a holley 950 hp carb on my 355 sbc. I just started racing after some time off and could use some help.The carb has power valves in the front and rear but I heard of some people just blocking off the rear power valve and upping the jetting in the rear. The combo is a 12/1 355 with a 630 nitrous roller aluminum heads,2055 intake and 160 exhaust,team g intake and the 950 carb. The jetting is 78 fronts and 82 in the rears with a front 3.5 power valve,the rear power valve im not sure of off the top of my head,i gotta check.
One run I shut it off to check a plug and the plug was white and I wanted to get some opions before I run it again. Timing was at 38 total. Thanks for the help.
Greg
sometime's you need to make more than one run to get any colour. if ya did'nt hear any rattle try another couple of run's to see if you can get some colour, then go from there.
 
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