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I got my carb from Pro-Systems last week and was wondering if anyone can help me interpret the data sheet that came with it. Some of the info is obvious but much of it is not, at least to me. I'm wondering what CFM this carb flowed at, but I don't see it here. Patrick said initially that it would be around 760-780cfm. I can call him and ask, but I thought I'd see if anyone here could help me read this first.



 

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Well, since he started with a 950HP body, I'd guess it's at least 950 unless he's washed it in hot water and it shrunk!!
 

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JTW,
I just pulled my sheet that came with my HP 950 carb that Patrick built. He said he wanted to see mine at 820 -830CFM when we first talked.
My jetting is 78/88 and about the only other thing I see different is my lean rich averages change because of the jetting, as well my P/S pump is 30/50 .
My Static draws are 851, 892, and 902.
2 weeks before I got the Patrick Carb, we had done " another " 9 dyno pulls trying to get my 750 Demon to regulate a reasonable flat A/F curve. I believe over 2 years, we pulled that carb 20 times on 3 different dyno's trying to rejet it to work. BG techies, when they saw the last 9 pulles, wanted me to start drilling the metering block yada yada, and I already had 76 front 93 jet back lopsided big time. I said if I have to modify that much, I might as well get something that is tuneable to my needs.
When we bolted Patricks on, it cranked, filled the bowls and when warm, went to 6,600 RPM, and it was flat like a pancake for A/F. 2 weeks to the day that BG said I had to hammer and chisel thiers to work.

That is why I never called to ask Patrick to interpret what it flowed, I didn't give a hoot, as I was happy like a cat with a live mouse again.
 

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When patrick says he wants to see xxx amount of cfm, that is wet flowed. Manufacturer's rate thier carbs dry flowed (just air). Things change when you mix fuel in with the air it's flowing. So a 950 HP holley might only flow 850 wet. That right there is why Patricks carbs are awesome.
 

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Discussion Starter #6
ryan63 said:
When patrick says he wants to see xxx amount of cfm, that is wet flowed. Manufacturer's rate thier carbs dry flowed (just air). Things change when you mix fuel in with the air it's flowing. So a 950 HP holley might only flow 850 wet. That right there is why Patricks carbs are awesome.
I thought all Holley's were based on wet flow numbers, and only Edelbrock's cfm rating was based on dry flow numbers. I'm pretty sure one of my engine books stated that. It said, for example, that a 750 VS Holley cannot be compared directly to a 750 Edelbrock because the Holley acheives that number at wet flow compared to the Edelbrock which reaches that number at dry flow.

Patrick said he expected 760-780 REAL cfm (meaning wet flow cfm) when we originally spoke, which is why I was surprised that sheet said 849, 882, 905. That seems like a big difference, but I trust he knows what is best.
 

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JTW,
I called Patrick and left a message for him to call me and explain the static vrs wet, vrs dry CFM's for us, so that an informed answer can be given on this site.
When he calls back I will reply on the site.
My carb has been on since June of last year, so its getting close to a year now.
How time flies when your pressing the pedal to the metal.:D
 

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I didn't know that, I thought all the manufacturers numbers were dry.

Either way your carb should help tremendously, Pat knows what hes doing for sure. I've seen 11.80 cars pick up to 11.50's with a pro systems carb built for thier combos, and the guys weren't idiots with a way off tune carb in the first place.
 

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Discussion Starter #9
68SSGrandpa said:
JTW,
I called Patrick and left a message for him to call me and explain the static vrs wet, vrs dry CFM's for us, so that an informed answer can be given on this site.
When he calls back I will reply on the site.
My carb has been on since June of last year, so its getting close to a year now.
How time flies when your pressing the pedal to the metal.:D
Awesome, thanks Grandpa! I'm traveling all week for work and I wouldn't have been able to call him 'til next week, so this is a big help. I'm anxious to hear what he says.
 

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Discussion Starter #10
ryan63 said:
I didn't know that, I thought all the manufacturers numbers were dry.
You may be right, I don't know this for sure. I don't have access to the book where I think I read this.
 

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Trying to figure out how each company rates their carbs flow numbers is a bit of guessing game. Each has their own way of doing it. Some wet some dry.Some at 28"H2O others at 1.5" of mercury. When the general public started to think they knew what flow was, carb companies started raising the depression they were checking the carbs at. While this technically isn't a lie, it is a bit misleading for the general consumer. What they thought they were getting may actually have flowed less air when comparing two carbs at the same depression. Holley really makes me giggle. They don't know what they want to check stuff at.The hp950 is a 750 main body with an 850 baseplate. I think you can do the math and figure out, if you use their standards, what that carb really flows. That 950 number doesn't relate to anything that i can find on my bench. It probably just sounded good to the marketing guys when it went to public.
With that being said, the cfm a carb will move is one of the last things a good carb modifier looks at when designing one for a particular application. Venturi diameter, taper, throttle plate diameters, metering and emulsion curcuits, booster design and placement all are much more important than getting the carb to flow another 25 cfm. If they want more air flow out of it, you just make it bigger, but if bigger was better everyone would have a dominator on their scooter. Patrick does an excelent job on all of his carbs. I know when people call and ask "what does is flow" trying to compare numbers he just takes a deep breath,puts on his smile, and tells them. He also realizes that he can give them something that will most likely be much better than what they have,if he has the correct info, even if it flow less air. If you want to see him smile sometime, ask him how much taper he used in the main well of your carb, or what the orrifice diameter of the booster is and how much signal did it generate. Or even better, find out what those things mean, and you too can be educated enough to know the difference when you see it. Know what an change in emulsion size does. How it relates to rpm and high speed bleed diameters. All of these things will make you a much better tuner and impress your buddies. :)
shawn
 

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Just got off the phone with Patrick James.
To recap what Shawn has said, the 950HP has a 750 body. Holley choose the 950HP number as a model number, maybe to make it sound like it was a massive carb, its not, it starts life as a 750 main body.
With changes in boosters, venturie, etc. Patrick changes the actual CFM of a 950HP to as low as 600CFM, and up past 850CFM.
The numbers posted on the bottom of JTW and my numbers are electronic signals of fuel shear, atomization, and other propriatary results of what Patrick Does to the carb. They do not reflect CFM.
Therefore, when he wanted me to be around 830CFM, and JTW at about 760, he has modified the downleg boosters, venturie size, and other internal items, to get us what our engines want as optimum CFM, keeping foremost fuel atomization, shear and velocity requirements.
DriveWFO is correct, that the shear, and atomization of how Patrick makes the fuel seperate is one of the keys to his very successful carb business. He is not about to discuss this on an open forum, and I don't blame him:shh: .
His unbelievable success, and the demand for his product says it all.

His product simply works, but more importantly, pay attention here:
He Phoned Me at 8:15Am to discuss this CFM topic.
I purchased a single carb from him, I am not a retailer, a mass seller, just a single customer, asking a simple question, and he takes the time to call.

Take a peek for yourself www.pro-system.com
 

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68SSGrandpa said:
His product simply works, but more importantly, pay attention here:
He Phoned Me at 8:15Am to discuss this CFM topic.
I purchased a single carb from him, I am not a retailer, a mass seller, just a single customer, asking a simple question, and he takes the time to call.

Take a peek for yourself www.pro-system.com

I race at us 131 (martin MI), Patrick is there racing his own car occaisionally and I've seen him totally devote the day to helping other people out and not concentrate so much on his own car. Alot of times these are people who don't even have a pro systems carb, he's truly a great guy.
 

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thanks guys,,i have had my demon since they first came out in 99 and ive been looking for a new carb

just got off the phone with him and all seams as said

filling out the form write now..so hopefully in a few weeks ill send him the money

thanks for this thread!
 

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Discussion Starter #18
Seattle_Mike said:
So how much do they cost compared to other vendors products?
In my opinion, his prices are pretty reasonable. That's saying alot considering I had already bought a $275 Holley Street Avenger and sent it back to buy one of Patrick's carbs. The carb I bought from him, which was custom tuned for my application, was $590. You can see the details here: http://www.pro-system.com/proseries4150.html. Considering that the Holley "Street" 4150 HP 750 DP is $450 and the Holley 4150 HP "Pro Series" 750 DP is $630 at Jeg's, his prices seem very reasonable.
 

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Discussion Starter #19
ryan63 said:
I race at us 131 (martin MI), Patrick is there racing his own car occaisionally and I've seen him totally devote the day to helping other people out and not concentrate so much on his own car. Alot of times these are people who don't even have a pro systems carb, he's truly a great guy.
This is a sign of someone who truly enjoys and loves what they do for a living. We should all be so lucky.
 
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