MTFCA Forum

I just saw the post not that long ago about adjusting the float level to cure a skip of the engine when pulling a hill and such. I can't seem to find it back! Pretty sure I've got the same thing going on. Thanks in advance!
Mike

If your OF runs fine except for "pulling long hills" I doubt that the float (fuel) level is the problem. I'd be looking at the economizer travel and/or the high speed jet adjustment. The fuel level should be exactly 1" below the machined top surface of the float bowl, and I usually install a sight plug to check this dimension with the bottom of the threaded hole at the 1" mark. Another way to check the fuel level is to clamp the carb in a vise by the mounting flange, attach a funnel to the inlet and feed gas into it till the funnel shows that the level is stable in the funnel. Now while holding the needle clamp, loosen the lock nut and back out the needle valve 1/2 turn at a time until the fuel level rises enough to flood the carb (by fuel appearing at the bottom of the throttle shaft). Now turn the needle valve back in 1-1/12 turns, tighten the lock nut, and you'll be close enough. Dry up the damp area around the throttle shaft and double check the level again, leaving it sit and stabilize for an hour or so while watching for even dampness at the shaft . This will also expose any leaking needle/seat problem. I usually leave my rebuilds sit with fuel in the funnel for 24 hours to double check for needle-seat issues as well as tiny leaks at any of the brass plugs.

Bruce, Would you care to elaborate on how you adjust the economizer valve and it's proper operation? I recently found out there is a slight difference in the height or dimensions of the OF bowls from early to late. Thanks for your input!

The economizer circuit is designed to allow more air into the mix at lower speeds (closed to partial throttle position) and is controlled by an arm activated by the cam under the throttle arm. When the throttle is closed, the cam through a small roller attached to the economizer arm holds the economized valve up (open), and as the throttle opens and the cam moves with it, the position of the cam allows the economizer to drop (close). Near the end of the travel and all the way to wide open throttle position the economizer valve will be fully closed cutting off the extra air previously allowed into the circuit. First thing to check is that there is freedom of movement where the economizer arm contacts the little brass adjusting nut insuring that the economizer valve is free to close tightly when the throttle is totally open. The travel of the economizer valve lift should be approx 1/8" and can be adjusted by the small brass nut (and cotter pin) or in some extreme cases, by bending the cam down to compensate for wear on the steel roller on the end of the economizer arm. Normal wear will tend to limit or restrict the overall travel of the economizer arm/valve, but a bent cam, arm damage and/or poor adjustment could cause the valve to remain open too long or not close completely, giving a lean condition. As for the fuel bowls, although one feeds initially through the top and the other feeds directly through the bottom, both OF designs have basically identical bowls/float systems, and the fuel level setting is always 1" from the machined top surface. Most lean conditions in an OF are the result of excessive wear at the throttle shaft/bushing due partially to the side load from the economizer cam. I think Corey is making new shafts.

Thanks for the education! I'll check it out tomorrow. Runs great, but when pulling a hill I'll get a sputter. If I open the throttle more I can hear it wants to go but almost makes sputter worse?

Try backing out the high speed jet 1/2 turn and go for a drive. Better yet, note exactly where it is now, and using the screwdriver slot as an indicator, carefully turn it in till it gently seats and count the number of turns it takes. Most instructions say a good starting point is 2 1/2 turns out but probably 80-90% of the ones I've done like close to 3 full turns out.

I had the stumble on flat level roads this year. I had forgotten that 4 years ago I had the same stumble problem when I went to Ireland, it took 2 days to locate the problem because it was so obscure it never crossed my mind nor that of the all the local garage employees where the car was recovered to. If the specific gravity of the fuel changes it will alter the float level, I agree not by much but enough to alter the float level and cause the stumble. Sunoco mentions this on their website.
Nigel Hugo.

Michael, did you get your problem solved?? Bruce

I believe so. We took a benefit tour yesterday. I opened the high idle needle 2 clicks before we left. Hog heaven, smooth like glass! About 20 plus miles into it the car starts starving out. Full choke would get you another 50 yards. Got a armpit of gas a couple times thinking I had crud from from the gas tank running a wire. Took the carb off today. Took it completely apart. Blew everything out. Putting it back together I notice the lock nut on the bowl needle isn't " locked "! It vibrated closed! Not sure if I'm close to setting the float level or not but I got a few miles on after adjusting and locking! They were good miles not struggling! Thanks for your insight,

Sounds like you need to set the float (fuel) level. You have two choices; with the carb held level in a vise, slowly pour fuel into the bowl through a small funnel until the level in the funnel stabilizes and then begin backing out the needle maybe 1/2 turn at a time until the carb floods (fuel will appear at the bottom of the throttle shaft in the bore of the carb. Now turn the needle in 1-1 1/2 turns and that will be close enough. The other way is to drill and tap a 10-32 hole in the side of the float bowl so that the bottom of the threaded hole is exactly 1" below the machined top surface of the bowl. Then adjust the needle so that the fuel level is just approaching the bottom of the threaded hole. Put in a short 10-32 screw and gasket and you're good to go.