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when i sadly decided to check and see if my idle tubes were clogged or restricted i bought new ones, and the new ones have a smaller stepped orifice then the old ones i destroyed

do i need to drill the new ones out or leave them alone?

the old set were .042 and the same bit wont set into the new set which are i assume .035


any input???
 

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when i sadly decided to check and see if my idle tubes were clogged or restricted i bought new ones, and the new ones have a smaller stepped orifice then the old ones i destroyed

do i need to drill the new ones out or leave them alone?

the old set were .042 and the same bit wont set into the new set which are i assume .035


any input???
The idle tube ID is just one of several points that have to be coordinated together to get the idle mixture the way you want it. The main thing is to balance the size of the idle tubes to the size of the idle air bleeds.

If the upper idle air bleeds are in the airhorn and are around 0.050" to 0.060", the idle tube ID you were given is fine. If the upper idle air bleeds are in the main body, they can be 0.065" to 0.075" and will work well w/the supplied idle tubes.

This will work well w/a cam that's relatively mild. If you know the cam specs, post them and we'll see if the idle tubes look to be compatible w/the cam. ALL the engine specs along w/gearing, etc. will be even better.

Do you recall the original primary jetting and metering rod sizes? Some "large main air bleed" Q-jets used a big jet and are tuned differently. Any idea of the original application of the carb you are working on?
 
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