Speed master billet carbs.

[Dave B]

Has anyone used the speed master carbs with tubes ?My brother has put boosters in them and made a nice carb out of one.Was just wondering how the tubes work and if guys used 2 or 3 circuit metering blocks?
Thankyou

[1980RS]

At almost $1000 for one of those procomp carbs, I will stick with my Holley's and QF Demon stuff.

[Dave B]

At almost $1000 for one of those procomp carbs, I will stick with my Holley's and QF Demon stuff.

My brother just buys those 100.00 billet main bodies and uses Holley pieces to finish.I doubt he has 400.00 in them when done.But just wondering if anyone tried them with tubes instead of boosters?

[1980RS]

At almost $1000 for one of those procomp carbs, I will stick with my Holley's and QF Demon stuff.

My brother just buys those 100.00 billet main bodies and uses Holley pieces to finish.I doubt he has 400.00 in them when done.But just wondering if anyone tried them with tubes instead of boosters?

The only tube carburetors I know that work are the Brasswell carburetors. If those tube main bodies were the hot ticket, everyone would be using them.

[Dave B]

I have bought several carbs from Braswell,never saw a tube carb from him.Have had several sv1s in shop and it took some work to make them happen.The speed master ones are pretty big venturi.We have a 1000 hp 540 dyno mule we test crap on.I guess I will try one of those tube deals on it.

[FC-Pilot]

Let us know what you find.

Paul

[1980RS]

I have bought several carbs from Braswell,never saw a tube carb from him.Have had several sv1s in shop and it took some work to make them happen.The speed master ones are pretty big venturi.We have a 1000 hp 540 dyno mule we test crap on.I guess I will try one of those tube deals on it.

My bad, it was C and S Specialties that makes them.

[Dave B]

Yes I have used those.They don't go clear across venturi like these do.We have 475 BBC bracket turd on Dyno.We took our baseline davinnci e85 carb that we Dyno with.Did 804 hp.My brother redid one of the speedmaster with boosters,made it 2 circuit.It had to have some things machined and changed.It made within 3 hp of our Dyno carb.We threw tube carb on after this.Cheap 90.00Baseplate.Cheap billet blocks,90.00.The tubes are smaller dia than our booster stakes in our other carbs.We made a quick buzz pull and not really load it hard.It was lean and then went fat .That being said it was down 17 hp.I will make some changes and maybe move their intermediate circuit and go 3 circuit and try it later.These carbs have some things that need addressed but I'm going to start using them more often.Have 400.00 area in them and some work.I can't touch a Holley carb new for under 650.00 now days.The Davinnci is 1.565 venturi.The one speedmaster we have is 1.550 and other is 1.570 that we tried with tubes.I need to flow it to see where it's at.The one down fall is they are way heavy.Take like a Blp billet body ,waayyy lighter.I will make a cnc program to lighten one of these things this winter.All in all with parts being a bitch to get ,I may pick up a few of these and start playing with them in different variations.You won't pull one out of box and be good to go.They definitely need addressed.I can't think of one thing we buy in race parts that don't imo

[FC-Pilot]

Dave B, I had a friend bring me one of their (pro comp) original carbs years ago to run on his engine on the dyno. It did the opposite, it started very fat and went extremely lean. We made two changes to bleeds and jets and it still acted stupid, so we put it on the shelf and I handed him a 750 holley I had. The old holley ran just as expected. I had to replace all the boosters as they were all machined crooked and internally were different sizes. I spent WAY TOO MUCH time trying to get things fixed in it. I have yet to even run it since the work. I expect it to work now if I ever get around to it, but that is after considerable work.

Again, keep us posted as to how it goes with that thing. I could imagine the removable boosters being useful in that body so you could swap boosters around to see what it liked. Also, thanks for he report.

Paul

[jmarkaudio]

Where is the venturi on the body in relation to the booster? The Pro Comp/Speedmaster billet bodies with boosters, not tubes, were copied from a Dambest body where the venturi is above the booster. In the case of the Dambest the booster is a bell booster, forcing the actual venturi pint to the bottom bell part of the booster. With a standard straight booster it will NEVER work correctly. The venturi point in the body should be right at or slightly above the bottom of the booster. Speedmaster uses R&D, rip off and duplicate, without understanding the physics involved. Don't waste your time.

[FC-Pilot]

The procomp carb I fought with was one of their cast (holley copy) carbs. There was no consistency in Venturi sizes or any machined areas like jets or bleeds. I don’t remember the size of the main wells, but they were extremely small compared to standard holley stuff. As an exercise in stubbornness and stupidity I went through everything I could think of to try and mimic a standard holley carb. Every main well, Venturi, bleed and location. I even replaces the improperly machined boosters with stepped holley boosters. It was either trash it (which looking back would have been cheaper and saved time and frustration) or try and see what it would take to fix.

As I said I have not even tried to run it, and it has been sitting for years now. Some day I will test it and see if that “fixed” it. If so, it shows that they have zero value if the fixes and initial investment cost more than a name brand decent carb would. I never recommend these carbs. I was curious of Dave’s experience and if it was similar to mine.

If I want to work on and fix a carb, I can buy and old used one and improve/restore it for less cost and get better performance out of it. Just my two cents.

Paul