Secondaries don't hold vacuum with vacuum pump

[440beep]

Yes, that is exactly what that 1992 Chrysler Power article said too. And that if you found a used Six Pack for sale that was the first thing to look at and if the passage was blocked by lead shot to not buy it. Article said it was pretty impossible to fix that.

Just for your info, people do drill and tap the kill bleeds ( you remove the diaphragm and drill through there) then use brass plug with holes drilled in them for their application. The first mods where to pound a piece of lead shot in there to block it off compleatly so the secondaries would open almost instantly.

 

[440beep]

I have to keep reading this post for all this info to sink in. I've been confused as to what holes I need to block in order to hold the vacuum, and thought I was supposed to be blocking 1 of the 4 brass colored "holes" on the side of the main body. BUT now I think I understand that there should be a single hole in the venturi (on the diaphragm side) that needs to be blocked. The new gaskets should be delivered today so I will test this out tonight and see if I finally understand what I'm supposed to do.......

Exactly, or do the same to the carbs one at a time.

The kill blead is the small hole inside the venturi, if you stick your finger down the throat of the carb where the diagram bolts to it you will feel a small hole, it must be blocked to hold vacuum.

 

[440beep]

Thanks everybody for the help!!!! Got the new secondary diaphragm gaskets in, plugged that bleed hole in the venturi, applied vacuum and the secondaries opened and stayed open until I released my finger from the bleed hole!!! Thanks for teaching me something!!!

 

[383man]

Just for your info, people do drill and tap the kill bleeds ( you remove the diaphragm and drill through there) then use brass plug with holes drilled in them for their application. The first mods where to pound a piece of lead shot in there to block it off compleatly so the secondaries would open almost instantly.

Yes you are right as I just meant they dont come that way like many billet metering blocks do but I kinda said it the wrong way. The six pack tuning guide that many use tells about that I believe. But I did not think they actually tapped and threaded the kill bleed for a type of jet like we do in idle restrictions and air bleeds. I just figured they filled it and redrilled it to the size they want ? In theory Holley should have it the perfect size to bleed off just enough vacum and then the hole be large enough for the venturi vacum from that throat to help pull and hold the vacum diaphram open. Many make it smaller to help the secondaries open faster but if to small it wont help hold them open once it turns into a vacum source after the secondaries are open enough and stops being a vacum bleed. I guess with a light enough spring they may be able to fine tune it enough to work right. Also I did mean to offend you in any way and if I did I appoligize. Ron

 

[383man]

This may help you understand it better. This is a vacum secondary four barrel but the six pack works basically the same. What they call secondary venturi pickup is what most call the kill bleed. Ron

 

[440+6]

Yes you are right as I just meant they dont come that way like many billet metering blocks do but I kinda said it the wrong way. The six pack tuning guide that many use tells about that I believe. But I did not think they actually tapped and threaded the kill bleed for a type of jet like we do in idle restrictions and air bleeds. I just figured they filled it and redrilled it to the size they want ? In theory Holley should have it the perfect size to bleed off just enough vacum and then the hole be large enough for the venturi vacum from that throat to help pull and hold the vacum diaphram open. Many make it smaller to help the secondaries open faster but if to small it wont help hold them open once it turns into a vacum source after the secondaries are open enough and stops being a vacum bleed. I guess with a light enough spring they may be able to fine tune it enough to work right. Also I did mean to offend you in any way and if I did I appoligize. Ron

No offence at all Ron , we are all here to help each other learn, I hope I didn't come off that way. Anyway one of the guys that got me into six bbl's in the late 70s raced a six bbl cuda and had drilled an tapped for a brass set screw (pretty common mod), at that time I was told not to mess with mine on a street car.
Also the first 69.5 A12 cars had a larger kill blead and it was corrected for the later A12s and all 70 and up so they would open a bit sooner.
I think that's about enough about kill bleads, not the most interesting subject. Frank

 

[383man]

I agree with you Frank. I myself have never owned a 6 pk car but I went to auto training in school and been a tech all my life for forty years as I have worked with many carbs over the years but most of them were basically stock. All the performance work was just for myself and my friends. And to be honest I am a Double Pumper lover when it comes to carbs as they are just so easy to keep in tune and I like my hotrod to be simple to work on. But I do love the 6 pack cars a ton and would love to own one some day. Ron