carb jet size

[murph]

I am rebuilding a 3236 weber carburetor and modifying according to the lola registry site. I need to know what size to use on the main jets and the air jets. Any help would be greatly appreciated. I already modified the top half with new dump tubes.

[Steve Demeter]

It will depend a lot on the state of tune of the engine, the manifold etc to get the ideal sizes and track testing, reading plugs, pipe and so on.. But someone ought to be able to give you a good starting point.

[Bill Manofsky]

I am rebuilding a 3236 weber carburetor and modifying according to the lola registry site. I need to know what size to use on the main jets and the air jets. Any help would be greatly appreciated. I already modified the top half with new dump tubes.

You need to 100% go to Rollin Butler or Ivey and ask them for a starting point for the jet sizes, then the rest must be done on a dyno nearest the tracks you race to set everything up to that local barometric pressure. You have to use the dyno to find where to best position the dump tubes and then what jet sizes to use. You have to size the jets based on the EGT readings. Otherwise you risk burning a piston being too lean. 1 and 4 will be the hottest. Pistons start to melt around 1500F.

All this is because the distance from the carb through the "less than ideal" Kent intake manifold to 1 and 4 is much longer than to 2 and 3.

So the reason why you only need the one dump tube on the outer Venturi on a 2 L Pinto but need two dump tubes on a 1600 Kent.

You can also try by just looking at the color of you spark plugs, but you will have no idea what your final EGTs will be.