so for example say my primary is a 70..

would a 140 be twice the size or is it indirectly porptional?

make sense?

anyone know?

 

TTT plz

 

what are you tring to do?? do you have porting? exhaust? Racing Beat has a jetting chart fot Nikki carbs, you should check it out!

 

The number refers to the diameter. 70 is 0.70mm, 140 is 1.40mm and so on.

 

you are the man

im converting to the car to run on alcohol.
so i have to ~double the jet size since it takes about twice the alcohol to run stoich as it would gas

 

the float bowls are not big enough to run alcohol!!!! needle valves are too small too! good luck!

 

Where do you find the jet size chart?

Chris

 

in the old racingbeat catalog

 

was talking to an old school racer(had several alky SBC's and has a pump gas 8.70 sec nova, that time is off the bottle, but its just a lil 400 shot ) had him look at a spare carb i got laying around

he said with the holley balck(alky compliant) and some work on needle/float that hes going to do, i shouldnt have a problem with fuel starvation, only reason i am even thinking of runnin alky on the nikki is becuase i dont want to try and run a 48ida on the stockport motor. If i pop the motor oh well im building another 12A bridgeport(slowly).

Im just trying to see how fast i can go on a stockport motor and decided WTF why not go alky.

4.77's go in on Tues and lightweight flywheel and clutch from horsepowerinabox as soon as i get it.

 

If you double the diameter of the jet, you'll be flowing much more than twice the fuel. The amount of flow is dependent on cross-sectional area of the jet.

pi * radius ^2

3.14 * .35 mm ^ 2 = .3848 mm^2

3.14 * .70 mm ^ 2 = 1.5394 mm^2

Which means you'll flow 4 times as much fuel!!!

In order to flow roughly twice as much you'll need to multiply .70 mm jet by the square root of 2 (1.4142)

.70 mm * 1.4142 = .989 mm

So, you'll probably be a lot closer with a 100 jet.