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how do you change them on a car with pressed in bleeds? Do i have to try and drill the old ones our and screw in the screw in type? I'd hate to do that on my original carbs. Is there a way to change something on the Promax jet plate that would accomplish the same thing?



AAR:

Another way besides the wires is to drill out the original air bleeds (after measuring them and recording the sizes), tap the channel (usually 8-32) and buy some brass set screws from an industrial supplier like McMaster-Carr. 3/16" length works well for IABs and MABs. Drill the brass set screw to the desired diameter and screw it in.

Wires work, but it can be kludgey. If the wire isn't inserted perpendicular to the orifice you're trying to reduce, its effective footprint becomes larger than the measured diameter of the wire. The upside, of corse, is that you don't risk messing something up when you drill and tap your carb.

In your case, yes the smaller MABs will richen it at the top end and delay the start of the mains at low airflow (thereby possibly making a lean spot off-idle). Juggling a larger jet and smaller MAB might be the ticket; only testing will tell.

Aren't you running aftermarket metering blocks? If so, how many emulsion bleeds and what size are they?



i have the promax metering block and the jet plates for the outboards. i dont think the jet plates have provisions for adjustment other than they accept holley jets. the center carbs metering block has the stock emulsion bleeds in their now.

I would imagine i'd want to be messing with the outboard MABs but I really dont want to go and drill and tap them. Im not really a numbers guy but on this, date coded 0500 original 6bbls carbs, I dont want to make a permanent change by drilling them.

Is there a way to change the center carbs metering block oriface to get this done? of maybe the jet plate oriface could be modified??