Vote for the Carb(s) I test on the Dyno!

OK, sometimes I can't help myself from posting this sort of stuff... even when I probably shouldn't for a variety of reasons. None the less...

I have an ever-expanding collection of 4150-type carbs as listed below. As much as I'd like to throw each one on the engine dyno to see what's what, the reality of time constraints will likely limit testing to two, maybe 3, if any level of dialing in a particular carb is to be done.

In addition, one carb that absolutely needs to be in the subset being tested is the #1 carb in the list, because that's the last baseline I have and what was run successfully on my car in the past.

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1. BG Race Demon RS set up w/ 1.42" venturi sleeves
=> previous tune as used on my car when it ran 10.5s as driven to the track

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So... that means you can pick two (2) of the remaining carbs listed.

2. BG Gold Claw set up w/ 1.50" venturi sleeves
=> new & untested config
=> pushing the limit for venturi size w/ downleg boosters that I believe will work well on my car

3. QFT/Proform 1.45" venturi main body used as basis for complete carb
=> original boosters; new & untested
=> Basically a Proform "950" with a better tune

4. QFT/Proform 1.52" venturi main body used as basis for complete carb
=> BLP modified boosters; new & untested; this is the limit for venturi size w/ downleg boosters I'll try
=> comparable to a QFT Race-Q 1000, which Quick Fuel used to win the small-block class in the last BLP Carb Challenge held a few years ago

5. QFT/Proform 1.59" venturi annular booster main body used as basis for complete carb
=> original boosters; new & untested
=> comparable to a QFT Race-Q 1050-AN, which AndyF said has been the best performing 4150 carb he's tested so far

6a. Holley Ultra HP/XP 1.60" venturi carb re-fitted with Mark Whitener's custom annular boosters
=> purchased from AndyF 'cuz I thought it looked "interesting"
=> Dominic "Thumper Carbs" worked on the tune to make it more driveable vs its original dyno tune

6b. Same as #6a, only with Holley Ultra HP/XP 1.56" venturi main body blended out to 1.58" and equipped with the same 12-hole annular boosters as the #5 carb
=> new & untested config
=> Mark Whitener's flow testing of a variety of carbs showed the modified Ultra HP/XP 1.56" (1.58") venturi main body flowed noticeably better than Holley's 1.60" venturi body... so I decided to build one

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Do your votes really count towards what I run? Ummmm... nope.

The final choices are still mine, but I'm interested in hearing people's feedback & thoughts on the subject, regardless.

Before anyone says anything about it - right, no Dominators.

I'm A$$uming most people are familiar w/ my junk, as much as I've posted over the years.

If you're not, the $.05 tour will be brief:
- 440 street/strip car
- 3800#s w/ driver
- pump fuel... that'll probably need to get spiked w/ some race gas cuz the CR is now up to 11.5
- 4500-stall converter
- 4.10s
- 275/60R15 DOT drag radials
- Guess-timating the new combination will make... 650+ HP... and the car "should" be capable of running closer to 10.0s once sorted out

OK, back to all the other stuff I have to deal with. - Brad

Well you're going to have to test them all at some point so you know what to keep and what to sell.

If it was me I'd test the carbs in order of how important the carbs are to you. If you paid a lot for them, or if you think they should be the best then test that one first. That way you test the stuff you care about most in your limited testing time. If you have some carbs that you don't really care about anymore then sell them now before you waste any time on them. If you can't sell a carb without trying it then you'll just have to try them all....

Seems to me you need to try 6a and 6b since you've recently invested money into them just to see if they are going to work. I'd think that those would be so close that one of those will get sold. I'm also going to guess that one of those carbs is the best of the litter.

carb #3 and carb 6b.

but andy has a point too, 6a and 6b would seem like a test that you would want to do...

Another idea is to do a BOB and WOW test. This is something we always trained new engineers on. BOB is "best of the best" and WOW is "worst of the worst". It gives you a quick way to sort stuff out.

In this case you'll be guess which is the BOB and which is the WOW but even the guess can be informative. If what you think is the BOB turns out to make the same power as the WOW then that tells you something.

#5 is what I have on my 512 street car. so yeah test #5

Send a carb to Dom and have him tune up it. Use that as your base carb.

Is this testing going to be on a engine dyno or chassis dyno?
Test the three biggest ones, #5 and 6A
Are you going to change the jetting on all of them or not?

That would be 6a, as noted in the description.

Also, 6b is 6a with a main body swap, not two separate carburetors. That's why they're not listed as 6 & 7.

Engine dyno.

Bringing lots of brass, but time is always a factor.

Brad ,
#1 , 4 , 6b

#1 because it is a known unit .
#4 bigger venturi same style . I ran a HP1000,1.56 venturi , on my 440 . Very happy, more power than my BG 825
#6b , a little bigger again . But if #4 shows improvement this will then show if annular is better for your motor .
Then you will have to try them all again on the street / strip to confirm results .


Tex

Marks boosters and Thumpers tune on #6A should be a good test against #5.

Sorry, I flat missed that.

hi ,

i vote for trashing them all and using a holley 3 bbl !

I vote for the 1050 QF carb with downleg boosters. That one was better than the BG 850 and just a handfull less HP than an 1150 Dominator on my build.


Ron

1, 5, 6a & b

Then, time permitting 2 or 4.

If they aren't "close" ootb...... It can really eat up dyno time trying to sort them out.

IMO, with limited dyno time available, if you bolt one on and it's just out to lunch...... I'd put that one aside and try a different one.

Dyno shmyno! Put them on a good, known car and figure it out. I'll go with the 6's!

The #6 still needed some work when I sent it to ya but figured you'd see what your combo needed to dial it in I just know it was stupid phatt across the board as delivered and killed my oil. Should be fun testing either way then of course in the car it will/may change as most seem to from my experience...........good luck either way.......

I made my picks, but I'm in agreement with Andy on this point...... Test the ones you think will be/want to be the best first.

Edit- after hearing Doms comments about the 6a being a little fat..... I guess I'd start out with the known quantity tune of the #1 carb.
No point in risking washing the rings down right off the bat.

I'd do the initial run it with the #1 carb, get it all warmed up, lash the valves, make a couple pulls ...... And hopefully that carb has a decent enough fuel curve to establish a baseline without having to do a bunch of tuning on it.

The next carb I'd try would be the 6a.

Brad,

What criteria are you planning to use to evaluate the carbs? Peak numbers, area under the curve, something else??

What throttle blade size do these carbs have?

TEST THEM ALL, LET DYNO SORT THEM OUT

6a was dialed in pretty good when I ran it. AFR was in the low 13's, made 650 hp on my 470 back before the intake was ported, BSFC was 0.400, Correction Factor was 1.02 so pretty good air. Dyno shop is close to sea level.

My dyno sheets show that we had 88 and 99 jets in it for those pulls. That was the Mark W tune. Worked great from 3500 to 7000 rpm. If you're testing near sea level then I'd use the original Mark W. tune and let it rip.

#5, 6B will be nearly identical but 5 gets the nod. Scrap the 1.60 you got from Andy for the test. And the Race Q1000 down leg should be a 1.500 venturi, that might be an interesting test against the 1.59 annular.

Makes sense that as MOST dyno's do from 3500-7500 and up it may have been ok but trust me, it killed my oil n plugs below that and could NOT even do a burnout. I'm not bagging on anyone or pointing fingers but on the steet where it matters most, it was a pig and I know it was loaned out as well so who knows there. IIRC, it had .080-.090 but not 100% and not near my book..............I see zero reasons to EVER run a 4150 on any motor making good power and have proved it many times even on small-blocks that have picked up a several mph and .010's so me, I'd ditch/sell em all and put a real carb on that puppy........... And .088-.099 jets........that's insane and even 1250's rarely run that size which should tell ya something...........

I had been thinking along the same carbs to test (the QFT 1.52 downleg & the QFT 1.59 annular) along w/ the baseline BG.

The Holley 1.60 annular conversion is sitting on a stand ready to bolt on (except I did notice the linkage is binding for some reason). No reason not to at least throw it on to see how it does... time permitting.


That's what I expected, too (i.e., 1.50" venturi). However, I measured mine after you installed the BLP boosters and found it measured 1.52", and later on found a QFT spec sheet that listed the RQ-1000 as 1.52", also. It makes sense, considering their venturi increases from "950" to "1000" is .07", and from "1000" to "1050" is another .07".

This is the carburetor equivalent of "Kill 'em all. Let God sort 'em out.", right?

The evaluation won't be strictly on peak HP & torque #s, but also the fuel curve, amount of air being used, differences in where a particular carb might show better than another, etc.

I've seen where two carbs that made virtually the same power on the dyno still ran .2 & 2 MPH differently on the car. Whatever looks like the most worth testing based on the dyno results will still get flogged on the car to prove it.

Yes

Just put the motor in the car and run it...

NOTHING in my life is that simple...

Any chance you have more carbs than you need Brad?

Oh wait, before you answer that would you like to buy a carb Brad? I don't think I need my QF-1050-AN anymore now that I switched to EFI so I'll make you a good deal on it.......

Why the He11 would you think that???


That reminds me... can you provide me w/ your QFT RQ-1050-AN tune so I can duplicate it w/ all the parts I have sitting around to build one myself?

And that is what I was wondering. If the criteria isn't clear going into your test, you may pick the wrong carbs to test. To me, it would seem that the best criteria would be area under the curve, in the RPM range encountered during the run; the right carb for a narrow range is likely different than for a wider range. Not knowing any of those details, my vote would be for 1, 4, and 6B.

The on-track differences like I pointed out were due to shift recovery (how quickly the carb adjusts to change in RPM & load) characteristics, which a basic engine dyno doesn't take into account.

Survey says...
#4
#5
#6a

That's all for now!