Do any of you guys know how to adjust a holly carb with a vaccume gauge? Is it the same way as an carb where I just adjust the adjusting screws till the valve peeks on the gauge for each adjustment screw? Thanks!
I think I tried it 30 some years ago, then decided to use the best lean idle method...screw both screws in till they seat (gently) then out a turn and a half. Then when it's idling (after it's been warmed up) turn them both in a bit, see if idle speed goes up or down, repeat this procedure trying both in and out till i get the best idle combined with the fewest turns out...then if it's a hot rod with a big cam, back them out a little bit more, if it's a stocker leave them there. then test drive, if it hesitates off idle I'll richen it up a little, etc. till it runs good. It would be helpful if I'd put a vacuum gage on and see what this looks like on the gage, but I never have.
I adjust timing and carb with a vacuum gauge, going for the highest most stable reading you can get. I have also done hydraulic lifter adjustment this way but it is messy. The vacuum gauge is one of my favorite tuning tools, and if you mount one on the dash like some 50s & 60s cars had from the factory, it will also train you to drive towards better efficiency.
I have a vacuum/boost gage on my 55, and I love to get the boost up as high as I can. I don't think I'm properly trained to use it for economy
Well I had a local classic car shop adjust it and he adjusted infront of me like you said and by ear. I was just curious because I could never get my edebrock to a good place. I called edelbrock and they recommended me using a vacuume gauge, so I did and it ran perfect. I was just curious If it was the same way. Cool, I'll check it with the vacuume and see what happens. Thanks!
I find that the vacuum gauge is the best way of setting the carb and the timing period. Make sure you are connected right off the manifold and have a good connection. You want the most vacuum you can have on the carb and with the timing I do the exact same thing and then just back it off a little and you should be good to go. If you leave the timing where you have the most vacuum it always seems a little to advanced for me at least with a 350 Hope that helps. Jimbo
I do the 1.5 turns out, get the highest reading on the vacuum gauge and if I'm really fussy, I'll listen to the exhaust while a trusted helper find tunes the carb... just a 1/16 th turn in... perfect! Bob
I do it both ways, but just remember that you have to wait a little bit between adjustments for the carb to react.
Last 302 I built, I got 23 inches of vacuum @ 750 rpm... It idled oh so sweet!.. I also rebuilt the Holley 600 #1850..
Some of you may find this link helpful. http://www.junkyardgenius.com/holley/tune01.html Also this second page to it. http://www.junkyardgenius.com/tools/vacgauge.html