Loss of carb adjustment

Berghandler · Feb 8, 2016

I had recently redid my carb on my 1949 8N because I had gas running out when I choked too much and not starting good. Took carb. apart and soaked it in carb. cleaner overnight. Cleaned it out very good. Then put a rebuild kit into it. Now no gas problem and start's good but when I try to adjust idle and load/run adj. needles I have no noticeable difference in running of tractor. I do get plenty of black soot at the tail pipe so I think it's running rich, but when I try to adj. nothing really happens to performance while running??? Also have no increase/decrease in first 1/4 of throttle so an adj. of governor might be necessary but that's just a spring tension increase/decrease by bending more or less. Not sure why no adj. at carb. screws?

HCooke · Feb 8, 2016

"so I think it's running rich,"

What is the condition of the air cleaner?

old · Feb 8, 2016

A Cooke says and or you still may have a clogged main jet so the down pointing needle may not do any thing due to the main jet being clogged up. When you clean a carb you need to poke a wire or as I do a torch tip cleaner tool in all the passageways and spray hem out with carb cleaner after poking them out

JMOR · Feb 8, 2016

(quoted from post at 18:17:06 02/08/16) I had recently redid my carb on my 1949 8N because I had gas running out when I choked too much and not starting good. Took carb. apart and soaked it in carb. cleaner overnight. Cleaned it out very good. Then put a rebuild kit into it. Now no gas problem and start's good but when I try to adjust idle and load/run adj. needles I have no noticeable difference in running of tractor. I do get plenty of black soot at the tail pipe so I think it's running rich, but when I try to adj. nothing really happens to performance while running??? Also have no increase/decrease in first 1/4 of throttle so an adj. of governor might be necessary but that's just a spring tension increase/decrease by bending more or less. Not sure why no adj. at carb. screws?

f you can not adjust the main power adjust needle (load/run adj) all the way fully CW until seated & result in killing engine, then say so, because that is a major point in diagnosis.

tekman1966 · Feb 8, 2016

I just started having the same issue. Did you do an extensive rebuild kit or just a basic?

Royse · Feb 8, 2016

As JMOR asked, can you kill it by shutting the main needle
all the way down? You should be able to.

Try running it with the air breather tube disconnected to
eliminate the air cleaner as the problem. Temporarily of course.

If the throttle worked well before, the governor may be fine.
How tight is your throttle shaft seal? Does the shaft turn freely?
It has to seal, no doubt there, but it shouldn't bind.
I put a lot of different carbs on my tractor every year. It matters.

I agree with the black smoke being a rich condition.
Did you take the brass jets out of the carb?
If so, did you put them all back in?

Berghandler · Feb 9, 2016

I had cleaned all passages in carb with wires and then cleaner pressure from a arrisal carb cleaner can. I'm not at the tractor right now but I do believe that I had tried to adj. main jet out a number of turns and all the way in and also same with idle jet adj. with no result to running engine whatsoever. The kit I used is a basic kit but I did replace the throttle shaft, (butterfly shaft I call it) with the new one from the kit. I read many of the past comments on this site with similar problem before I redid carb. so I believe I had a good idea from these experts of what to do and look for and hope I followed them as described. I had removed all parts, cleaned them and replaced or used them again as needed. I did not remove any bushings just threaded needle brass parts. New parts included throttle shaft, needles gasket from what I remember.

kylemorley · Feb 9, 2016

Hard to really clean a carb without compressed air. Spray can just doesn't put out enough pressure.

You read a lot of posts here like yours, where someone rebuilds their n-series carb only to have it run the same, or worse than before, and usually also finding the mixture needles aren't doing anything. I suspect the problem is inadequate cleaning (and unsuitable carb cleaners that don't work well on iron) loosening up the crud but not getting it all out. Solution? Find a suitable cleaner, soak the carb in it for several days, go wild on the internal passages with wires etc, then blow the heck out of it.

Oh, careful about blasting compressed air into the carb while the float is installed, as it can warp or collapse it.

Berghandler · Feb 9, 2016

I did use compressed air very generously but only soaked for a day with aged new carb cleaner. It's an easy disassembly now to resoak. I'll try to soak longer and clean out again but I do believe it's as clean as it's going to get on the inside.
Thanks

JMOR · Feb 9, 2016

(quoted from post at 22:19:22 02/09/16) I did use compressed air very generously but only soaked for a day with aged new carb cleaner. It's an easy disassembly now to resoak. I'll try to soak longer and clean out again but I do believe it's as clean as it's going to get on the inside.
Thanks

f you can not adjust the main power adjust needle (load/run adj) all the way fully CW until seated & result in killing engine, then say so, because that is a major point in diagnosis.
"I do believe...." isn't a good answer. Find out before removal & re-clean. Lack of clean may not be the problem.

Geo-TH,In · Feb 12, 2016

Neighbor put a rebuild kit in his marvel carb, lost adjustment, running too rich. If you can turn the main jet all the way in and tractor still run, you may have put a fiber washer on main jet that will not allow you to turn jet in far enough. Turning the main jet in all the way will block all the fuel, main and idle jets. Engine can't run without fuel. So remove the fiber washer under spring on main jet and see what happens.

KL-VA · Feb 12, 2016

This horse is already out of the barn, but gas running out the bottom of a flooded carb is normal. Gas running out any other time is probably a stuck float valve. Remove carb bowl drain plug and run some fuel thru the system while rapping the carb with a wooden hammer or screwdriver handle. This is no reason to rebuild a carb if it runs good otherwise. Hard starting is usually ignition. Fix that first. Once carb is in pieces, nothing short of a complete cleaning will do. Soaking only one day and air pressure isn't good enough. Most of this has been covered by others: I use guitar wire to help clean all passages. It acts like a rasp and also helps drag solvent into the passages. Make sure jets are proper size and all the way seated. Better to re-use an old one than replace with a wrong one. Throttle shafts must seal. Float seat must be all the way down on the gasket. Adjust the float. If seat is in right, float adjustment is usually just straightening float arms to restore from previous misadjustment. Main jet must be able to screw all the way down to the seat.
KL

Bob · Feb 12, 2016

If the venturi was not installed correctly, or broken/cracked/bent/damaged, OR the gasket between the upper and lower halves is damaged/defective/wrong the carb mixture adjustments will be affected and the carb will act "goofy".

Loss of carb adjustment

Berghandler

Member

HCooke

Well-known Member

old

Well-known Member

JMOR

Well-known Member

tekman1966

Member

Royse

Well-known Member

Berghandler

Member

kylemorley

Member

Berghandler

Member

JMOR

Well-known Member

Geo-TH,In

Well-known Member

KL-VA

Member

Bob

Well-known Member

Similar threads