case 400 carb

(quoted from post at 23:10:17 12/12/12) put in a bigger venturi and drill out the load jet if needed

How big does it need to be drilled out? 267ci cam by baker heads lightly massaged
 
big enough so you can get black smoke, you should have a wire bit set and go a size or two at a time, had to do it to a 400 carb on a 331ci dc engine, treadwell will have venturies, motec told me once that you don't hardly need one, I don't agree with that
 
Why waste your time dilling one sized at a time? Dill it out to .093 and be done with it. You can always turn the load screw in if it is to rich.

Motec make his own ventuies. Bigger than you will ever get from Treadwell. Motec can built a better carb than Treadwell for about half the price.
 
Remove the discharge nozzle and see if there is a jet deep down in the carb, if so remove it, drill the main jet adjustment seat just so the taper will still set on it. Leave the jet out of the passage in the carb. Many do not even have it.

Doug, my carbs for big displacement engines are straight wall venturi but I wouldn't recommend that for stock or near displacement engines. Most will start rite up with no choke. If I want high performance info Motec is my man, Treadwell are great people and do a lot of actual manufacturing of obsolete parts and I use them , but due to Matt's work with big displacement pulling engines and feeding them with stock appearing carbs I feel he has the edge in performance apps. Matt taught me over the fone more than I ever knew about MS carbs, he readily shares info.

mEl
 
i'm not doubting his abilities and we have discussed this but we pull speed limit often at low rpm's until the load starts coming on and I am a believer on having a correctly sized venturi for throttle response, when I talked to them he pretty much said you didn't need much of one which would be ok at higher rpm's
 

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