Are there any good "trick" carbs?

General engine tech -- Drag Racing to Circle Track

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Are there any good "trick" carbs?

Post by David_D. » Wed Jun 18, 2008 12:05 pm

With all of the carb threads, and the discussions about trick carbs not necessarily being worth the money over a well tuned out of the box carb, I was wondering if there are any trick carbs that do work extremely well?

I have a "trick" carb that I am very happy with, but I wanted to see what others thought.
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Post by Doug Schriefer » Wed Jun 18, 2008 1:05 pm

I don't believe there is an out of the box carburetor that can compete with a properly tuned and calibrated race carb.

Now with that being said a lot of it will depend on the type of racing you're doing and what you require. If you look at high level carbureted motorsports you won't find an out of the box carb in the field...

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Post by andyf » Wed Jun 18, 2008 1:07 pm

It all depends what you mean by trick. Years ago the Holley carbs were basically black boxes that were very difficult to tune. So people began to make billet metering plates that had replaceable idle jets, pvcr jets, etc. That stuff was trick and those parts really helped. The magazines used to be full of articles about how you could stick wires in the idle jets to lean out the carb or drill out the pvcr to change the AF ratio at WOT. No need for those hack fixes anymore.

These days you can buy a Holley UltraHP right off the shelf with all of that stuff in it. They come with the billet base plates, billet metering plates, sight glass bowls, notched floats, drilled throttle plates, etc. The main body is already smoothed and radiused right out of the box.

If you compare an old 850 DP from 1970 to a new 950 UltraHP I think all of the aftermarket tricks have already been included in the new carbs. Not sure what trick means anymore.

There are only a few carb tricks I see in the aftermarket that Holley doesn't offer. One is the nozzle approach where the booster venturi is replaced with a dump tube. The other trick that Holley hasn't embraced yet is the slotted base plate so a 4150 carb will also fit on a 4500 intake.
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Post by David_D. » Wed Jun 18, 2008 1:15 pm

I was thinking more in the line of carbs from builders such as Quick Fuel, Pro Systems, APD, Rupert...the list goes on...vs. a pre UltraHP HP carb. Most of these carb customizers put billet base plates/metering blocks on the carbs and "tune" the fuel curve to your engine combination. How much better, if any are they over a Holley HP carb? Again, this is pre UltraHP.
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Post by Doug Schriefer » Wed Jun 18, 2008 1:18 pm

David_D. wrote:I was thinking more in the line of carbs from builders such as Quick Fuel, Pro Systems, APD, Rupert...the list goes on...vs. a pre UltraHP HP carb. Most of these carb customizers put billet base plates/metering blocks on the carbs and "tune" the fuel curve to your engine combination. How much better, if any are they over a Holley HP carb? Again, this is pre UltraHP.
I'll state it again... It depends on the type of racing you're doing. You're not going to find an out of the box HP on any Pro car around. Teams would not spend thousands of dollars on custom carburetors if they could run better with a stock one....

I'll put a properly built race carburetor up against anything out there any day of the week and twice on Sunday...

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Post by David_D. » Wed Jun 18, 2008 1:23 pm

Doug, I'm talking drag racing specifically (since that's what I do).

When it comes to custom carb builders, do you have a preference?
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Post by andyf » Wed Jun 18, 2008 1:30 pm

Well what exactly is a tuner going to do that somebody with a screwdriver and a wide band can't do with an UltraHP? The UltraHP allows you to change emulsion jets, idle jets, pvcr jets, main jets, intermediate jets, air bleeds for all three circuits, etc. So if you can tune every single circuit on the carb what else is there to do?

Tuners used to do things like conversions to four corner idles and stuff like that but once again, the newest carbs have that all built in. Holley has been fairly aggressive over the past 10 years about grabbing up ideas from the aftermarket and folding them back into their designs.

Now there are tricks out there that you can't get from Holley, for instance BLP makes some really nice stuff such as the 3 circuit metering block whree the idle tube is separate from the main well. For people who complain about 3 circuit carbs going lean on the top that might be the solution.

Another trick that the average guy might have trouble with would be changing the length of the transition slot.
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Post by Doug Schriefer » Wed Jun 18, 2008 1:30 pm

David_D. wrote:Doug, I'm talking drag racing specifically (since that's what I do).

When it comes to custom carb builders, do you have a preference?
Since I work for one not really fair for me to pick... But I can assure you that there hasn't been a P/S or P/M car even qualify with out of the box carbs in years...

You're looking at a couple of things going to a properly set up carburetor.
1) The tolerences are much closer (same as blue printing an engine) so with the proper carburetor you're going to run more consistently.
2) Working with a good carburetor tuner is going to give you an advantage with your tuning to get the most performance out of your car. They're going to be more up to date on current technology and what is required to get the performance you're looking for.

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Post by Doug Schriefer » Wed Jun 18, 2008 1:33 pm

andyf wrote:Well what exactly is a tuner going to do that somebody with a screwdriver and a wide band can't do with an UltraHP? The UltraHP allows you to change emulsion jets, idle jets, pvcr jets, main jets, intermediate jets, air bleeds for all three circuits, etc. So if you can tune every single circuit on the carb what else is there to do?

Tuners used to do things like conversions to four corner idles and stuff like that but once again, the newest carbs have that all built in. Holley has been fairly aggressive over the past 10 years about grabbing up ideas from the aftermarket and folding them back into their designs.

Now there are tricks out there that you can't get from Holley, for instance BLP makes some really nice stuff such as the 3 circuit metering block whree the idle tube is separate from the main well. For people who complain about 3 circuit carbs going lean on the top that might be the solution.

Another trick that the average guy might have trouble with would be changing the length of the transition slot.
And yet even you say how when you bolt on your Braswell carburetor it makes more power than the stuff you've tuned... So based on your logic stated here you should be able to make as much (and actually more since you're there tuning on it) HP than your Braswell..

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Post by David_D. » Wed Jun 18, 2008 2:07 pm

My custom tuned carb is doing what I want it to, and I'm happy with it. As much as I would like to learn about doing the tuning myself, I don't have the opportunity at the track to do this (limited testing, and I'm there to race, not tinker).

The experience with my carb is based on results at the track, not on a dyno. I'm pretty sure that my custom carb wouldn't have produced better numbers on the dyno than when it was untouched, but it's more consistent than before. So for me, it's different than PS/PM because those guys want max power and to run as quick as they can. Bracket racing, I want consistency.
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Post by Doug Schriefer » Wed Jun 18, 2008 2:09 pm

David_D. wrote:My custom tuned carb is doing what I want it to, and I'm happy with it. As much as I would like to learn about doing the tuning myself, I don't have the opportunity at the track to do this (limited testing, and I'm there to race, not tinker).

The experience with my carb is based on results at the track, not on a dyno. I'm pretty sure that my custom carb wouldn't have produced better numbers on the dyno than when it was untouched, but it's more consistent than before. So for me, it's different than PS/PM because those guys want max power and to run as quick as they can. Bracket racing, I want consistency.
That is the main thing you have to use a carburetor designed for what you are doing...

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Post by harry k » Wed Jun 18, 2008 2:48 pm

where is Troy P. ? www.tmpcarbs.net (TMP : TRY MORE POWER)
the forefront of trick carbs :)
he needs to chime in this as well !!
someone who thinks logically is a nice contrast to the real world.

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Post by andyf » Wed Jun 18, 2008 2:49 pm

Doug Schriefer wrote:
And yet even you say how when you bolt on your Braswell carburetor it makes more power than the stuff you've tuned... So based on your logic stated here you should be able to make as much (and actually more since you're there tuning on it) HP than your Braswell..
Not sure where you came up with that statement. I've run a lot of Braswell carbs on the dyno and they have always made really good power. The Braswell stuff usually does better than any customer carb but the usual customer carb is an older Holley non-HP style carb. When I've done Braswell vs. UltraHP carb type of tests I usually don't see much if any difference on the dyno.

Braswell does have some stuff that Holley doesn't have, for instance the extra fuel circuit options that would be important for circle track guys. So if someone needs to run in a class where mileage is important then a carb like that could be the difference between winning and sitting in the pits getting a tank of gas.
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Post by harry k » Wed Jun 18, 2008 2:53 pm

what does Brasswell offer for drag racing any better than Holley ?is there any ? just curious
someone who thinks logically is a nice contrast to the real world.

Neivn15

Post by Neivn15 » Wed Jun 18, 2008 3:42 pm

bigs carbs all the way

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