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| Carb Question | Login/Join |
| DRR S/Pro |
Mr Retread, I am responding to your statement above more for others reading this and that your statement above is false. Carb's just respond to air flow and based on their setup (fuel curve) and provide the amount of fuel for a given amount of air flow, more air, more fuel! The size of the motor means nothing, it's just the amount of air it draws in and based on that the carb delivers a programed amount fuel based on its fuel curve! Many racers believe you need to jet up when you put a carb on a big motor and down when you put it on a smaller motor - this is not true. If fact when racers swap carbs and pick up a bunch, it's usually not that the carb was bigger, it is because the fuel curve of the carb matches what the motor wants! Jetting up or down does not change the fuel curve shape, it just moves it up or down at all rpm's! And BTW, a 350 CID motor running at 8000 needs more air than a 454 running at 5500 is just one example of your false statement above! No pain, no gain!  | |||
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| DRR Elite |
TOP38...KNOWS! | |||
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| DRR S/Pro |
This is the formula that I was taught and still use: Cubic Inches X maximum useable RPM divided by 3456 X 1.2 for a single carb application or 1.5 for a dual carb application. Useable : does not mean how high you can rev the engine but rather where it still makes power not just rpm. Bob | |||
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DRR Top Comp |
I ran some of those numbers on my stuff and it is pretty accurate backed up by Dyno and track time. I believe that is different formula than we used to use which was much more conservative. Many think you need to jet your carb to cubic inch, altitude and some even change jets with every weather change. When a carb is set up right you rarely ever have to do anything other than blow out air bleeds and keep it clean. I also like to change floats every year in off season when running alcohol. https://postimg.cc/gallery/np3zpruo/ "Dunning-Kruger Effect" -a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge. Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue. 4X NE2 CHAMPION. 2020 TDRA NE2 Champion | |||
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DRR Trophy |
Thank You everyone for the input I am going to a tnt in a week so I can check out all of these inputs and let you Know. Thank You All Again. Merry Christmas and Happy New year. | |||
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DRR Pro |
Make a pass with fresh plugs and shut it off. See what the plugs tell you. If they show rich, jet down until car stops going faster. If they show lean, jet up until it stops going faster...Before you try another carb. From the sounds of things your carb isn't set up right.... Mark Goulette Owner/Driver of the Livin' The Dream Racing dragster www.livinthedreamracing.com "Speed kills but it's better than going slow!" Authorized Amsoil Retailer | |||
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DRR S/Pro |
If you are just going from one 41150 carb to another you shouldn't have to change anything except the carb. On that combination I would look at an APD, Getum', Pro-systems carb for that. I am sure there are people on here or around your area that have a spare or a different one for you to try and see, the mph will tell you the difference it made one way or the other. Unfortunately there is no majic trick. I have spent 1800 on a carb and it went slower, done the same and went faster but less consistent. Keeping the Socialists and NEO-LIBERALS at bay with FACTS one post at a time !!! Freedom isn't free !!! Thank a veteran, they will actually appreciate it. | |||
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| DRR Top Comp |
You're saying the same thing I said basically, only I should've possibly included WFO on a dyno! I don't build any engines I can't spin 8000 rpms if need be. Too much work and not enough bang!  | |||
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DRR Pro |
A properly built carb will flow the right amount of fuel to match the airflow drawn thru it with any engine. Ideally using the same jets for a 406 or a 632. The difference arises when one engine is more efficient at atomization and distribution in the induction. Differences from one fuel to the next, assuming non oxygenated gas the difference is minimal, usually a jet size either way. Oxygenated fuels will require more jet. So the big engine/small jet versus small engine/big jets doesn't hold water. It can go either way, and HP doesn't matter either.  Mark Whitener RFD Heads FTI Converter Fab Shop Headers Home built 2 circuit Dominator :-) www.racingfuelsystems.com ____________ Good work isn't cheap and cheap work can't be good. | |||
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| DRR Top Comp |
That is basically what I was trying to say. https://postimg.cc/gallery/np3zpruo/ "Dunning-Kruger Effect" -a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge. Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue. 4X NE2 CHAMPION. 2020 TDRA NE2 Champion | |||
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| DRR Top Comp |
Example I took the 1050 off my 406 and bolted it on my buddies 632. We jetted it up 2 jet sizes and his car was 2 hundredths slow from his carb. Put the small jets back in it I run, and it went 2 hundredths faster than his carb. Figuratively speaking - Big engines take small jets, small engines take big jets. Literally speaking - Big engines take big jets, small engines take small jets. | |||
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| DRR Top Comp |
Example 2 I took the 1050 off my 632 and bolted on my buddies 406, we jetted it down 2 jet sizes and his car slowed down 2 hundredths. Put the big jets back in it and his car went 2 hundredths faster than it ever had with his 950. Big engines take small jets, small engines take big jets - is an approach to take figuratively speaking. Small engines take small jets, big engines take big jets - is literally an error in approach. | |||
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| DRR Top Comp |
If ya'll had read the comment I originally replied to, you wouldn't be suffering from this confusion. | |||
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| DRR Pro |
Who is confused here? Not me... Mark Whitener RFD Heads FTI Converter Fab Shop Headers Home built 2 circuit Dominator :-) www.racingfuelsystems.com ____________ Good work isn't cheap and cheap work can't be good. | |||
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