Howdy folks,
I bought a new Carter YF from Mike's carburetors for my 1974 highboy with a new reman 4.9L and I have had trouble getting it to run ever since.

I trailored it to a friend's and he helped set it with a tachometer to get the idle at 600 like the sticker on the motor says then I drove it home and the next morning it wouldn't start. I looked around to see what was going on and noticed the screw for the warm idle adj wasn't even touching the part that it pushes into. I screwed it in and it started but it doesn't want to stay running.

Does anyone have simple instructions on how to set the screws to standard just so I can get it running again? I know the mixture screw is supposed to be 1 ½ backed out from all the way in but what about the idle screws? Is there a way to set them to a basic standard?

Thanks in advance any and all information is greatly appreciated!

 

When the engine is cold and the choke is closed, that main idle screw is usually not touching at all. So that might have been normal.
You'll need to hold the throttle open a little bit and then hold the choke plate open so that the high-idle cam and linkage release and let it settle down to the curb-idle screw. Then you can set the idle. But you really should only do that warm anyway, so that all the idle stuff is working at it's best.
If you do it cold you might get a change in idle speed when it's warmed up.

Setting the idle/air mixture screws is a dance. The recommendations are for getting it started, then it's up to you and the individual engine setup to turn them to whatever number of turns gets the best idle quality. You turn one until it idles higher and/or smoother, then turn the other one for the same result. Then you do it all over gain with the other screw to see if it's parameters have changed.
You might do this dance two, three, or even four times until you've got both idle/air screws where it runs best. And all this while you'll be adjusting and re-adjusting the curb-idle screw to put the idle back to the desired 600 rpm level.
Same thing for ignition timing. You set the timing first, then the idle speed and adjustments.

And back to the original dilemma, having the idle stuff wrong does not cause the engine to not start. Or even to be hard to start. Might be something else, or a combination of something-elses at work.
Maybe the choke did not close far enough when it was cold? Maybe the ignition timing is not set right? Maybe there are vacuum leaks? Maybe the main jets are the wrong size? Maybe the wrong PCV valve is causing too much or too little air to flow through that system causing a mis-match of fuel and air at the intake. Lots of stuff can work against you after a carb swap.

When it's cold and the air cleaner is off, flip the throttle lever by hand and watch the choke butterfly/plate/thingy. It should close almost all the way. There is a specification for how far it closes, but it's usually down to just a small gap (like 1/8" or so) left open. Once you start cranking and engine vacuum builds up, the choke pull-off opens it up to another specified opening to actually let air in and it can settle down to a smooth, but higher idle speed. At this point it should start easily if everything else is cooperating and the idle screw will not be touching the lever again.
Only after the choke opens up as the engine warms will the high-idle cam release it's own little screw (cleverly hidden on the passenger side of the carb) and the main idle screw takes over.

Are you familiar with carbureted vehicles and their little idiosyncrasies for starting? Just checking because it's been so long since they've been in production a lot of owners don't know the tricks of the trade.

Good luck. Probably a lot more than I mentioned here, so keep asking questions and others with a lot more carb-lore info than me will chime in too.

Paul

 

Really appreciate all the information! I am gonna try again and see what I can do!