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 1320 (Pontiac Straightline Performance)
 850 vs 950 carbs, watch out!!!!!!!!!!!!!
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DaveH
Tribal Scout

USA
12 Posts

Posted - 29 Jul 2008 :  12:51:28 AM  Show Profile  Reply with Quote
I've been running a holley 850 dp for years, and decided to try a Proform 950 main body. I bought one and after examination noticed the venturis were 1/8" smaller in diameter than my 850. 1/8" X 4 venturis, thats almost 1/2" smaller overall!! This is the same size as the 750 carb!! I called Proform, the guy told me through angles and port work and shaping and blah blah they are able to get 950cfm out of it. I installed it on my engine, it has increased throttle response as expected, and a little pop or backfire when i first start it, sometimes. Now I see Proform has a 1050 main body, I called them today to get the venturi spec, and it is 1.56", the exact same as my holley 850. The 850, 950, and 1050 all take the same base plate. The truth is, Holley, Proform, or anyone else, do not make anything bigger than an 850. Even Holleys 1000 cfm is an 850 body, so is Quickfuel's and Proform's 1050. The higher cfm ratings are determined at different levels of vaccuum readings, etc. etc. to get what they need to make sales. Also, the Holley HP 950 uses the 850/950 base with a 750 main body, go to holley.com and check the specs, you'll be surprised this is true. The largest venturi size listed (other than dominator) is for the 850. Real world tests will show, I have my 1/4 mile times with the proform 950, I am going to put the 850 holley main body back on there and see which runs quicker, at the track on the same day. I believe this is a misrepresentation by these manufacturers, someone should do a flow test, keeping all factors equal on all the manufacturers carbs and report the findings. Its like flowing heads at 25" or 28", we should be told what conditions the carb is being flowed at also. Heck, if I can get enough people to send me their carbs I'll do the testing and send the carbs back!!

i82much
Sitting Bull

USA
220 Posts

Posted - 29 Jul 2008 :  07:46:18 AM  Show Profile  Reply with Quote
Yeah I think it all started back in the day, another manufacturer - maybe BG? started rating carbs at different pressures than Holley so they had bigger #'s. In order to keep up, Holley rated their HP carbs differently than the old ones. It's a little misleading for sure.

Steve
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Mr. P-Body
Running Bear

USA
2258 Posts

Posted - 29 Jul 2008 :  09:05:20 AM  Show Profile  Visit Mr. P-Body's Homepage  Reply with Quote
Dave,

John Dickey of AED explained this to me a while back. The "950" isn't really... To move "up" from the 850, the 1000 is the next one that shows any real improvement. He said it was a marketing thing, as Steve has alluded to.

Jim
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Punisher
Sitting Bull

174 Posts

Posted - 29 Jul 2008 :  8:08:12 PM  Show Profile  Reply with Quote
The HP950 carb is based on a Holley 830 - the HP 1000 is based on a holley 850 - I never read anywhere that they actually flowed 950 or 1000 cfm and if you tell someone you have an HP 1000 415 0 on your car their eyes get real big like you have something huge - I tell them it is just a glorified 850...

Dominator is where it is at ;)
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Christ
Howling Wind

USA
1808 Posts

Posted - 29 Jul 2008 :  9:03:20 PM  Show Profile  Visit Christ's Homepage  Reply with Quote
Yes i ran 1050 dominator at the track. It quiet impresive to say least!
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Lucas
Cochise

USA
428 Posts

Posted - 29 Jul 2008 :  11:35:26 PM  Show Profile  Reply with Quote
I used to run a 800 dp holley and I got a 750 Demon for a good price. Put it on the car and jetted the same as the holley just for a base line. Car ran like you know what. I ended up going up 12 steps front and back to make it run. But the car ran the same E.T. after all the tuning. I really need to listen to myself when I say, "if it ain't broke,don't fix it." Next motor will need a dominator so that will take away any confusion.
Lucas

"wildfire"
Real pontiac power
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Punisher
Sitting Bull

174 Posts

Posted - 29 Jul 2008 :  11:51:34 PM  Show Profile  Reply with Quote


Here is mine...
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rickyrhea66
Tribal Scout

USA
1 Posts

Posted - 27 May 2016 :  7:14:36 PM  Show Profile  Reply with Quote
Have a1050an profrom on sbc runs to lean have 99 jets what's wrong???? How can u tell if I have the right blocks
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Lee
Sitting Bull

101 Posts

Posted - 27 May 2016 :  7:21:45 PM  Show Profile  Visit Lee's Homepage  Reply with Quote
quote:
Originally posted by rickyrhea66

Have a1050an profrom on sbc runs to lean have 99 jets what's wrong???? How can u tell if I have the right blocks




I had a similar situation, a few years ago. I had a carb that used jets in the 90's and had perfect AFR. I then swapped to a more aggressive intake manifold, which caused my previous jetting to be WAY lean. Even using 99's f/r it was still too lean.

At first, I bought some precision drill bits (I can't remember the exact size off hand, but will try to dig them up over the weekend) and drilled out some of my never-used tiny size 60-something jets, making them a few sizes larger than 99's. This got the AFR much closer, and the car ran better.

I later discovered that Competition Cams sells "hex jets" in all sorts of sizes. Based upon the drill sizes I used, I bought several sets of the Hex Jets slightly smaller and larger than what I drilled, and was able to fine-tune the carb.

CURRENT: '73 T/A clone, boring at the moment...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
www.LNLPD.com
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GtoGuy32
Cochise

USA
842 Posts

Posted - 27 May 2016 :  9:38:27 PM  Show Profile  Reply with Quote
What does your fuel system consist of? Fuel pump, lines, etc?

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Pontiac Dude
Sitting Bull

USA
199 Posts

Posted - 06 Jul 2016 :  1:47:44 PM  Show Profile  Visit Pontiac Dude's Homepage  Reply with Quote
quote:
Originally posted by rickyrhea66

Have a1050an profrom on sbc runs to lean have 99 jets what's wrong???? How can u tell if I have the right blocks




U need to change the air bleeds and that will fix the issue. ;)

## 1976 T/A, Hydraulic roller, 3460lbs, stock suspension & Pump gas. N/A: 9.78@136 ##

I Specialize in ALL American Muscle Iron.
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Edited by - Pontiac Dude on 06 Jul 2016 1:48:00 PM
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