[bullitt 2244]

here is the prob...600 cfm vacume secondarys...at an idle pulling the throttle open open, i do not see the secondarys open at all..why ? do i not have enuff manifold vacume?

 

[kendallt]

Didn't say what type of carb, but Holley's are notorious for having the vacuum diaphragm getting split and not opening. Another possible is that the cover for it gets a slight leak in it that simply passes vacuum.

Make sure that the base gasket matches the carb and that no passages are plugged with sealant or covered by the gasket. Also check that every movable thing on the carb moves freely, and that nothing is bent.

For most carbs, there is a spring under the vacuum diaphragm that can be changed out to adjust the vacuum needed to open them, try swapping to a lighter spring. holley sells spring kits that include several different springs, normally color coded but often the old spring color is gone.

 

[bullitt 2244]

hi kendallt,crow here..thank you very much for your input..info is well recieved and already passed on to my mechanic..

 

[SABL]

Good luck with the carb!! It's been a long, long time but I always "pinned" the secondaries to make them mechanical.....faster response and better control. Vacuum secondaries are about as good as vacuum windshield wipers.....yes, I have driven many vehicles that had those awful things!! Step on the gas and the wipers stalled.....not good in a downpour.

 

[kendallt]

Oh vacuum wipers, bring back memories
I had a 46 Willy's cj2a jeep.great little toy. It came with a vacuum wipers for the driver and a hand crank on the passenger side. After playing with it for a year or two and never getting it to be reliable, I found it was far more effective to put the hand crank on the driver side.

On converting vacuum secondaries, It does provide for more reliable opening. But many street engines aren't capable of handling the converted carbs and end up with a huge flat spot when the secondaries open up.