I am setting up the carb for the propane system. The carb that I am replacing is a holly 4 brl. w/vacuum secondary. The part that operates the secondary(vacuum actuator ??) is attached to the side of the carb as it looks to like it draws it's vacuum from somewhere on the side of the carb.(as you can tell by now I don't know too much about carbs). Now the propane carb that I got uses the butterfly plate off of the old holly. So what do I do about the secondary. I have a guy that is going to help me set things up but I would like to know for myself how to handle this little problem.

Thanks for any help
Maxx

assuming i am right here, u have an impco 425 mixer. all u hook up is the low pressure line. thats all i have hooked up. the only vac line i have running anywhere is the lil one that goes to my fuel lock(i have a non electric one) my butterflies are a holly as well,( i bought it new so maybe it doesnt have the secondary actuator., ill have to look someday! jiMMy

Jimmy, do you have any vac lines going to your distributor?

Originally posted by Mustard Dog
Jimmy, do you have any vac lines going to your distributor? yup, one lil one, thats for the vacume advance. jiMMy

You need to pin the carb linkage to convert it to a manual secondary. Then all will be good. I can probably take pics to show you how I did mine tonight..

Vacume secondaries do not work with the 425...

Originally posted by The Jerk
yup, one lil one, thats for the vacume advance. jiMMy

I have a centrifigul advance, but I was advised to hook up the vac line as well.

Just wondering were did you guys get your tanks? did you buy them used or new? and How much were they? I'm looking for a 13x13x32 and was told that they don't make that size any more so used is my only option
thanks in advance
Keith

Originally posted by SOS
Just wondering were did you guys get your tanks? did you buy them used or new? and How much were they? I'm looking for a 13x13x32 and was told that they don't make that size any more so used is my only option
thanks in advance
Keith i run 2 forklift bottles

Originally posted by Jason M
You need to pin the carb linkage to convert it to a manual secondary. Then all will be good. I can probably take pics to show you how I did mine tonight..

Vacume secondaries do not work with the 425...

Some pics would be great. Thanks

The propane carb is a OHG model 450, I assume that its much like the 425 in the way that it hooks up. My dad delivers bread and all of the fleet trucks used to be on propane and the fleet mechanic is going to help me out. I would hope that he knows how to do this, but just in case I figured I'd try to get some ideas from you guys.
Thanks
Maxx