HOLLY 750 Question???

[t1971Chally]

Hello guys,

I have a question regarding the Holly 750 on my 71 Chally 440 Magnum.  I have been adjusting the float bowls on my carb trying to get it to run correctly.  I have the primary adjusted correctly however I am questioning the secondary.  I spent a number of hours trying to adjust the secondary with no avail.  Everytime I would adjust it,,,,the float level would not change.  I finally took the screw and nut off of the top of the secondary bowl and WALLLA found the problem.  Who ever had worked on it before adjusted the "adjustment stem" down so far that the adjustment nut could no longer grab on or engage the stem to move up and down.  I was able to get the stem adjusted up enough that the nut could once again grab onto it.  However, heres where my question comes from.  After adjusting the float, I understand why it was down so far.  To get the float to a level that is acceptable (not to high), I to had to adjust the stem down to almost a point where the adjustment nut cannot grab it.  It there something else going on here?  Is there another aspect of carbs that causes this condition that I am unaware of?  Thanks for your help....

Ted

[Moparal]

Sounds like someone has had the bowl off before and tried to rebuild it. They must of bent the tab on the float to set the level with on the needle n seat.  Sounds like you need to pull the bowel and adjust the tab which means bend it down some.  Either way, it is an internal problem with the float. Very easy to fix

[BIGSHCLUNK]

I'm with Al on this one. Should be an easy fix. Hint from BIGS, I spray my gaskets w a little wd-40. That way if you happen to have the need to take it off the second time they come apart easy. And you can reuse the gasket! 

[wagesofsin]

I'm with Al on this one. Should be an easy fix. Hint from BIGS, I spray my gaskets w a little wd-40. That way if you happen to have the need to take it off the second time they come apart easy. And you can reuse the gasket! 

we buy the reusable gaskets.   

[Chryco Psycho]

What people forget is that when you adjust the float level down the carb is not using fuel from the rear of the carb so it doesn`t really go anywhere & the fuel is pushed over the float sight hole by the float displacing the fuel so you always want to start with the float level too low & adjust up .
 the float is as the others said , at somepoint the arm has become bent so adjusting it is difficult as it is virtually out of range

[t1971Chally]

Ok guys,

First, a big thank you to Al!!!  I just finished up pulling the secondary off and bending the tab upward and I am now good.  My next problem.  I have the float levels in both primary and secondary adjusted so that with the engine NOT running the fuel will seep out if you bump the car with your leg.  If the engine is running, it will seep out on its own.  I have read here on this forum and the net that this is the proper adjustment.  My next problem is I have to adjust the engine idle speed screw to the point the engine is idling at 13 or 1400 RPM in park to keep the engine running where as it use to idle at 8 or 900RPM.  I have hooked a vacuum gage to the carb and have between 15 and 17 inches of vacuum(i believe that is the correct term) at idle.  I read where the general idea with the vacuum gage is to adjust the fuel/air mixture screws evenly on both sides to the point that you maximize the amount of vacuum.  Is this correct?  Any ideas on what I can do?  Looking to get the idle back down to 800 or so......your thoughts?

Ted

[dodj]

If you are increasing the idle speed to keep the engine running, you are opening up the butterflies and the engine is probably no longer running on the idle circuit. Could be a vacuum issue but seeing as you had to fix the float tab.......maybe the previous rebuilder wasn't as good as he thought and your idle circuit is a little less than perfect.

[Aussie Challenger]

  Good info about spraying/reusing gaskets, but if it wasn't done from new the gasket may be leaking/blocking a passage allowing fuel or air to bypass into the secoundaries if old gaskets were reused.