Race carb or Street carb

[Ant]

I am running a Pro Systems 840 cfm street carb, double pumper ran 675bhp on my 373 SBF Yates engine at 7200rpm, apparently the carb is 10 year old and the part number indicated they were designed for the shelby corporation.

My thoughts are as my engine runs to 7000rpm and my use is street and road racing.

Is there any advantage getting a purpose built road racing carb???

This carb needs road race floats, it appears to have the modern contoured body etc and looked like a race carb.

My knowledge is limited in this field I assumed if the jets, pumps etc are ok and it flowed the right amount for my engine then all good. I read where race carbs have a different fuel curve as they operate in the 4000 rpm plus range which may be detrimental to my use of some road use, where I need a reasonable transition from take off. I don't think my engine has a great deal below 3500 -4000rpm, will find out one day when I get the project finished..

[blykins]

A custom carburetor suited to your purpose would be best. A lot of the new carbs from Quick Fuel (and other brands) are pretty much infinitely tunable, which helps when you need to have that "dual purpose" carburetor.

And yes, you need floats set up for a road race application.

[Frank Messina]

Just because it's 10 years old doesn't mean it's worn out or not a good piece. 675 HP from a 373 is pretty stout. Why not check with Pro Systems to see what updates if any your current carb might need to match your intended use. You may be shocked to find out it's good just like it is.
Frank

[Jac Mac]

You still planning ahead Ant or have you got that car running? Might have to break out of my self imposed exile to parts north this summer if you have!
Most holley based stuff needs at least a set of O-rings & gaskets after an extended homestay on the shelf.

[Ant]

Frank,

I checked it out with Pro Systems a few weeks ago, Patrick said it was a street carb not a race carb and if I fit road race floats that should get me going..

As I intend on doing a bit of racing and being reasonably serious with my build I am very curious to find out if a street carb is a disadvantage or try a race carb, although only testing will prove that and a race carb might have the same top end as my current carb and be less drivable.

The 840 cfm is a good size for my engine, made great consistent solid power from 4000 - 7200rpm when I did some dyno testing.

Originally Posted by Frank Messina

Just because it's 10 years old doesn't mean it's worn out or not a good piece. 675 HP from a 373 is pretty stout. Why not check with Pro Systems to see what updates if any your current carb might need to match your intended use. You may be shocked to find out it's good just like it is.
Frank

[Ant]

Hi Jac Mac

Building split case mufflers at present, big job with all the transitions and having a 2" OD insert that goes inside the 3" perf for road use, and getting through the certification process, still have heaps to do won't be going for a couple of years.

Carb was dynoed 2008 fuel drained has been sitting ever since

Originally Posted by Jac Mac

You still planning ahead Ant or have you got that car running? Might have to break out of my self imposed exile to parts north this summer if you have!
Most holley based stuff needs at least a set of O-rings & gaskets after an extended homestay on the shelf.

[Ant]

I agree Jac Mac it would be best to fit a gasket kit etc.

[Jac Mac]

Don't remember if I told you Ant, but we changed from a Demon to a Willies? carb on the TVR, cleaned up a mid range/part throttle stumble the car always had in the process, don't read much about them in the forums like this so don't know how they compare with others, just know that it worked for us!, has five settings for each main jet size that allows for those five jet changes without carb teardown/removal.Demon could have been fixed but time was never made available.

[Bobcat]

Ant ... FWIW , I sent my Pro Systems 950 HP back to Patrick this December for rebuild/update . About $200 US gets you a complete strip down/rebuild , new orifice plugs and any updates that are applicable to your carb/application .
I do HPD events and have the road race floats ... and they are required for a road course . I also have a street carb , but the Pro Systems unit runs almost as well on the street as the modified street carb and puts out a ton ( metric ) more power .

Bob

[Ant]

Jac Mac, The Willys carbs look good, and with the jet adjustment function. I see there is a great range of carb manufacturers out there, most producing good quality stuff.

Bobcat, I emailed Patrick and he came up with a 780 -800cfm carb for my engine, the one on it is 840cfm street carb, will check out other manufacturers and it would be interesting to compare what I end up with on the dyno with the other modifications I have done to engine. We won't be changing everything at once and next time we dyno will be with 3" straight through perf mufflers, instead of straight out the collectors like last time.

[Bobcat]

Ant ... good plan on using testing the motor with the mufflers you`ll be using . It made a significant difference on my carb setup as my engine was dynoed without mufflers and , obviously , I have mufflers and also merged collectors . Carb ran rich at light cruise and low rpm ( 2200 to 2700 ) with the on car exhaust system vs dyno .
Have fun !!

Bob