Page 1 of 1
Tuning my carb?
Posted: November 4, 2014, 2:39 pm
by Jacobs63
Ive been getting my 63 road worthy lately but the carb is stumping me. I'll admit I do t have a clue what I'm doing when it comes to working with carbs. My truck will run and drive it will only drive decent when the choke is closed. When opened it idles rough and inconsistent and will back fire. It's a fomoco carb on a 292. Can anyone school me on tuning this machine?
Re: Tuning my carb?
Posted: November 4, 2014, 3:50 pm
by rbeck204
go to the link below. it has more information than you asked for, but there is a section on adjusting the carb near the end. Hope it helps.
Rich
http://www.therangerstation.com/tech_li ... 0_carb.pdf
Re: Tuning my carb?
Posted: November 4, 2014, 8:09 pm
by Nathan390
Sounds like a vacuum leak.
Try replacing the base gaskets. That usually where I find the leak. Back side base gasket.
Re: Tuning my carb?
Posted: November 5, 2014, 1:46 pm
by bruceandersson
You can find the leak by spraying carb cleaner around the base of the carb. If the idle changes - there's your leak. If necessary you can do this at the manifold to head connection as well.
Re: Tuning my carb?
Posted: November 5, 2014, 7:32 pm
by Jacobs63
I did find a bad carb gasket. Fixed that but that didn't help the wild idle. Some time it idles really high and I tap the gas pedal and she calms down to normal. Any ideas on this?
Re: Tuning my carb?
Posted: November 6, 2014, 7:42 am
by bruceandersson
Check your choke linkage. There is a cam on the choke that should provide a higher idle when the choke is on and a lower idle when it is off. Make sure it is connected and nothing loose.
Re: Tuning my carb?
Posted: November 6, 2014, 12:16 pm
by ICEMAN6166
with truck off
unscrew both idle mixture screws all the way till they come out
inspect the points on the end and if needed carefully sand off any imperfections, there might be dirt on the end or little scratches etc.
use very fine sandpaper and spin the screw while applying light pressure
clean them off
put them back and turn both idle mixture screws all the way in, dont ram them hard against the seat, just snug till they stop turning
then back them both out 1.5 turns,this is a starting point for adjustment, the farther out,the richer the mixture
they usually end up somewhere between 1.5 and 2 turns out
start the truck up, if its stays running without the choke on, then adjust out till the idle is at its high point then turn back in 1\8 to 1\4 turn.
it should be noted that the carb is the last thing adjusted after everything else is correct, valve lash, dwell, timing as if these are not set to specs first you will be fighting and aggravating yourself
Re: Tuning my carb?
Posted: November 6, 2014, 5:34 pm
by Jacobs63
Great help ice. I'm gonna do all if this this weekend. The posted link gave me some good tips too.