So I had a previous thread about a hard start problem I was having and we fixed but I have a new/old problem. I set everything, on the 292 f100 with 2 barrel holley and electronic/vacuum mallory dizzy, to the normal settings. that is I have the initial timing at 10, the idle screws 1 1/2 out, and the idle speed screw so that the transfer slot had just the square showing to try to eliminate a bog I got whenever the accelerator was initially hit. The problem is that with the idle speed screw set for the transfer slot it has the engine absolutely running away from itself at like 3000 rpms. So I crank it back to 800rpms and it runs nice except for the bog is there when i first step on the accelerator and if I dont let up it will die. So off the line or when turning corners I have to really ease the gas or get on and off and then back on again. What am I doing wrong that the transfer slot setting has this affect? and or what can I do to fix the bog? Thanks for the help, I hope to get the same result as the hard start, that is fixed thanks to you guys, and the y-blockforever siters.
Cbass

 

This might be a good place to ask carb questions, also:

Ed's Carburetor Forum. Carbs rule!!!!

Another member told me about it,I can't remember who, though.

 

ck your vacuum advance on the diz just suck on the line with the cap off and make sure its moving all so ck your accelerator pump

 

You'll also want to make sure that when you set initial timing to 10 degrees, you must not have the vacuum advance hooked up. Also, make sure your vacuum advance is set to ported vacuum and not engine vacuum.

 

Vacuum advance is working, as well as the accelerator pump. The timing was done without the vacuum hooked up and it is hooked to the ported vacuum above the idle set screw. Keep the ideas rolling, something has got to fix this.

 

From Holley: You can try a higher # (larger) pump shooter size. The bog or hesitation may be caused by a momentary lean condition when the carb goes from the idle throttle position to the main metering system. The shooters help richen this momentary condition and eliminate the stumble. Keep going up in shooter size until a puff of black smoke comes out the exhaust, then go back one or two sizes.

 

Knock the advance back down to 6 deg or so. What is the factory spec?

You also could have a vacuum leak.

 

This was my first thought.....Is the bog worse on cold start-up, or the same all of the time?

 

Bog is the same all the time at initial giving of gas, no matter off the line or in 2nd gear. I will try larger pump shooter sizes on Monday and will cheak for leaks tomorrow. I will let you know how it goes.
Thanks
Cbass

 

It's possible to have so much advance that no amount of gas will prevent just what you describe. By reducing advance and opening up the carb a little to get to the same idle speed, you put the accelerator pump in a better position.

 

If I reduce the advance too much more it will start to die, it is right at 10 initial.

 

Ok, here we go. I went to the parts store and ordered the stuff I thought I might need to get this all done and fixed for good. Of course the parts are not in stock but they would have them tomorrow, so I went home to double check everything I could so that I would have a starting point. In doing so I got the timing dialed in perfect and the idle where I want it and gave it a shot with the accelerator pump and noticed it shot right away but did not look like it was getting full travel. I went to adjust the screw and check the gap at WOT and the screw was completely loose. I tightened it down and checked the gap, started the truck back up and sure enough with full travel that girl runs like a dream. I thank everybody that gave advice and say to you all to double and trip check everything even stuff you are sure you had working great a few months or weeks ago.
Thanks a ton and have a great New Year.
Cbass

 

Awesome news, good job! It's always the last thing you try.

Jim