Well I'm in the process of my very first carb rebuild. My question regards adjustment after it is back on the truck. I have a Holley 600 4 barrel with vacuum secondaries. The kit instructions give adjustment settings as you put it together but don't outline how to adjust the mixture etc. when the vehicle is running. The carb is on a '72 390 3spd auto. Thanks in advance for any help anyone can give.

 

[font size="1" color="#FF0000"]LAST EDITED ON 18-Aug-01 AT 02:08 PM (EST)[/font][p]on the holleys, the mixture screws are on the sides of the metering block. you turn screws clockwise to lean out the idle mixture, counter clockwise to richen it up. start by turning the screws out from seated 1 1/2 to 2 turns out, fire it up, then adjust accordingly. the needle and seat are adjusted by removing that little screw in the bowl on the right side and watching when the fuel starts running out. turn the screw counter clocwise to raise the float level, clockwise to lower. then secure the lock nut. the fuel level should be just below the opening. replace the screw when done.

Wayne 60 F-350
e-mail
http://home.pacbell.net/whomrig

 

[font size="1" color="#FF0000"]LAST EDITED ON 19-Aug-01 AT 02:01 PM (EST)[/font][p]Thanks for the advice, I'll try that when it's back on. I have the whole thing together now except for one part that I cannot figure out how to attach. There is a little red 'rubber' piece that appears to be some sort of one way valve, it is located under the accelerator pump. The old one was very difficult to remove and I was going to leave it in except that the kit had a new one. I damaged the old one pulling it out and now cannot get the new one in. Is there some sort of secret to this?
Forgive me if this is a stupid question but I'm stumped.
Thank you,
Don

 

Don, that is not a stupid question, but I have not seen a red rubber thing on a holley carb. The holley I have is a two bbl model on my truck. It has also been a while since I have rebuilt one of these.

Wayne 60 F-350
e-mail
http://home.pacbell.net/whomrig

 

Not sure about the red rubber thing
But for sett ing the adjustments try this >>>

Setting idle: Setting the idle speed and mixture on a Holley is very straight forward. First you should set the idle speed, using the adjustment screw against the throttle lever.If you do run a choke be sure to also set the fast idle speed (when the choke is closed.) Idle mixture is set by the tiny adjustment screws in the side of the metering blocks. On Holley's, backing the screw out makes the mixture richer (more fuel passes through the orifice.) We find the best adjustment is no more than two full turns out off the seat. If you have to go more than two turns out to get the engine to idle, you probably have another problem, such as a vacuum leak, or perhaps not enough idle speed. In some cases, especially with big cams and low idle vacuum, you may find that you have to crank the idle speed way up, and the idle mixture screws don't seem to make a difference. The problem here is that as you increase idle speed, more of the transfer slot becomes exposed, and the carb begins to meter through the primary circuit, causing a excessively rich idle mixture.
I don`t think this is necessary, but it is in the info anyway for Those that need to know to do it!
>>> In this case it may be necessary to drill a tiny 1/8" hole in each the throttle plates to allow some air to pass through, enabling you to close the throttle plates.<<< Most Holley books outline this procedure. __JOHN__Õ¿ö
FTE Club #7
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http://www.cruisin-north.com/
Santa Rosa, Calif.
72 F-250
ICQ#6030753
http://www.ford-trucks.net/users/jbhf250/
https://www.ford-trucks.com/pictorial/big/1972_f250_2.html

 

Thanks for everyones help, the little rubber thing went in nicely with a drop of oil for lubrication. A friend dropped by who has 40yrs experience rebuilding these things and he was able to get it all set up for me. Thanks again for the help.