So….. ever over carburate?
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71Demon540
Well-Known Member
Ya I’d try a bigger one. Just my opinion.
More examples of "race only" engines making more power with bigger carbs.
What 950, Old or new ?
ValiantRacing
Well-Known Member
I am wondering the same thing, i am going from the Speedmaster heads to ported Indy 360-1 heads and i am running an 850 now, do i need a 950 with head swap?
B3422w5
Well-Known Member
With the bigger heads you might be happy with the 850 you have.
Be better of going to a 1050 dominator over both 850 or 950.
jbc426
Well-Known Member
Car was faster racing around Willow Springs with the 350cfm than the 500 cfm. Racing is not limited to the drag strip. After all, hot rodding on the street was born from all kinds of racing on tracks. No?
That's true, o.p drag races though.
Point I was making was for dedicated race cars
& I disagree with everything bewy says
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jbc426
Well-Known Member
9secRR
Well-Known Member
funny **** right there
Always went faster with a bigger carb. Even the street cars posted better ET's. Had a dedicated race car that ran consistent 10.68 with a tunnel ram and 2 750 TR carbs on top and everyone said I had too much. Same thing was said when I plopped a 600 DP on a 289 Mudstain FB that had stock internals. Only other mods was a Torker intake and headers. It ran a 15 flat with a 2.80 gear. Mileage was great on the hiway but sucked in town....of course.
cubic inches x max rpm divided by 3456
But we're talkin about drag racing HERE. So why the HECK would we bring anything else up?
Then that means you're probably correct on everything.
jbc426
Well-Known Member
Actually, the OP mentioned his hot rodding history (street use). He could also be drag racing, racing on oval tacks or road courses in his past with that W8, which was originally designed for NASCAR racing not drag racing.
People like to add to conversations on these threads, some even like to post stupid jokes and cat pictures, and some will always complain just to feel better about themselves, so be it.
...and some like to be jerks. Go look in the mirror. Cya.
jbc426
Well-Known Member
lol, at least you're consistent.
The formula is excellent for finding the smallest carb you should run on an engine.
Never had a drag car that didn't respond positively to a larger carb.
When I raced sport bikes and one particular finicky class, we spent 3 days on the dyno tuning the carbs. The carbs had a spring, like a holley vacuum carb that control how fast the slides would move. Throttle plates could be wide open off the throttle grip, slides were like a secondary door on a carter/pod on holley vac sec. We'd go to a high speed track where the throttle was WFO and rarely down in the revs, light spring. Something like road atlanta before they ruined it (JMHO), something progressive to get the grunt pulling out of the slower corners but not so slow that you gave up the early part of the long back straight. We had about a dozen sets of springs for all the tracks on our schedule across the states.
Just depends on what you are doing whether a bigger carb/faster reaction carb will work for the situation. Nothing is a one size fits all, across all types of use.
Drag car, well tuned bigger is almost always faster.
Never had a drag car that didn't respond positively to a larger carb.
When I raced sport bikes and one particular finicky class, we spent 3 days on the dyno tuning the carbs. The carbs had a spring, like a holley vacuum carb that control how fast the slides would move. Throttle plates could be wide open off the throttle grip, slides were like a secondary door on a carter/pod on holley vac sec. We'd go to a high speed track where the throttle was WFO and rarely down in the revs, light spring. Something like road atlanta before they ruined it (JMHO), something progressive to get the grunt pulling out of the slower corners but not so slow that you gave up the early part of the long back straight. We had about a dozen sets of springs for all the tracks on our schedule across the states.
Just depends on what you are doing whether a bigger carb/faster reaction carb will work for the situation. Nothing is a one size fits all, across all types of use.
Drag car, well tuned bigger is almost always faster.
Sounds similar to a variable venturi.
I haven't read all the replies, but I have ran a 1050, 4150 flanged carburetor for a long time on my 408 sb. It's a 620 ish hp engine, shifting at 7400. I have had the same carb (besides metering blocks) on both race gas and E85. Everything on paper states its too big, but the car loves it.
I have had 318's that run better on 750 double pumpers than they would on 650 vac secondary carbs.
Only time I went "too big" was I tried a dominator once (on same 408 above) and I did notice some low end loss. But it's also a footbrake car.
There's a video out there of a 289, or 327 chevy being tested with everything from a 2bb to a 4500. It makes more hp with every increase, and I don't even recall if the 4500 hurt the torque much. I looked but can't find it.
Being the racer forum, I would say nothing wrong with borrowing one slightly bigger and seeing what happens!
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B3422w5
Well-Known Member
Wondering why a footbrake car would be any different than using a brake would regards low end. The car is pretty much going instantly to where the convertor hits at leaving via either method.
I have said this on here before, and found it to be true in real world results. If the convertor is specced correctly, the typical bracket type car will 60 foot and ET virtually identically either way.
I raced in a 10.00 series on a pro .400 tree using a brake( Griner brake) and that same day every event raced in a footbrake only bracket race.
The car ran the same either way. If you looked at the slip, no difference was discernable.
I have said this on here before, and found it to be true in real world results. If the convertor is specced correctly, the typical bracket type car will 60 foot and ET virtually identically either way.
I raced in a 10.00 series on a pro .400 tree using a brake( Griner brake) and that same day every event raced in a footbrake only bracket race.
The car ran the same either way. If you looked at the slip, no difference was discernable.
...and no matter how much you preach it, there will be those in disbelief.
Of course I’m talking strictly drag racing. I haven’t had a “street” anything since the mid 90’s. The car has finally come around to being very consistent….. so it’s time to change something! Let’s face it… bracket racing is just a math game where I can “time slip chase” for myself. For the amount of passes I make a year it’s just a really bad hobby at this point. Think I lost the data, but we dynoed the engine with a 4500 adapter and in house quick fuel 1050. When I first installed the engine for some test hits the only 4150 carb we had was a swap meet BG 750 that we’ve had forever thats mated to our iron head mill. IIRC we ran 9.7s. Next was the Braswell 4825 which was a neat piece. With that combo we got pretty solid in the 9.4s. When we ditched the Mopar 598 intake and went to the Miller and reworked 1050, we’ve gone a best of 9.09. So the pattern has always been that she likes air.
I'd honestly agree with you, with a converter that footbrake stalls at X RPM, and trans brake set at same X RPM, shouldn't matter. In my experience however, my trans brake cars have always managed to launch at a higher RPM, as footbrake stall is generally lower, and you're relying on the cars brakes to hold it back at least some.
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