carter carb adjustment help please

[010175]

Trying to adjust a carter carb that was rebuilt by someone and when the air adjustment screw is turned all the way IN the engine still keeps running just like it was 2 turns out. Is this normal? If not is their something that can be done with out removing it to rebuild it?
ie like just replacing the needle screw? Could the needle be bad or can the needle seat in the carb body be bad ? The 2 idle mixing screws do change the RMP and vacuum gage. I do have a shop manual and doing the step by step carb adjustment but its running rich still. Thanks Dave

[maxwedge]

Something is allowing air into the engine, vacuum leak, improper throttle linkage setup/adjustment, either way the carb should be rebuilt, this is a simple carb to work on.

[j cAT]

Originally Posted by 010175

Trying to adjust a carter carb that was rebuilt by someone and when the air adjustment screw is turned all the way IN the engine still keeps running just like it was 2 turns out. Is this normal? If not is their something that can be done with out removing it to rebuild it?
ie like just replacing the needle screw? Could the needle be bad or can the needle seat in the carb body be bad ? The 2 idle mixing screws do change the RMP and vacuum gage. I do have a shop manual and doing the step by step carb adjustment but its running rich still. Thanks Dave

as mentioned make sure using a vacuum guage that there are no vac leaks....also the carb base gasket...before adjusting anything..most times the carb adjustments are good the vacuum leaks screw things up..

next is the float needle valve may be in need of replacement or dirt has fouled the needle valve / seat...this will cause a rich condition as the bowl will overflow...

make sure your carb fuel filters are in good condition especially with steel fuel tanks.....................

[010175]

Thanks to all.. The best I can get the vacum gage to read is 19". I take it by the answer that the air adjustment screw when all the way in should kill the engine if there no other vacum leaks. Should i test for a vacum leak by spraying starter fuild around the carb? Not real for sure how to test for leaks. The carb looks good, ie no fuel leaks or seeping. Thanks Dave

[j cAT]

Originally Posted by 010175

Thanks to all.. The best I can get the vacum gage to read is 19". I take it by the answer that the air adjustment screw when all the way in should kill the engine if there no other vacum leaks. Should i test for a vacum leak by spraying starter fuild around the carb? Not real for sure how to test for leaks. The carb looks good, ie no fuel leaks or seeping. Thanks Dave

since you have 19 in of vacuum you most likely have no major leaks, as this is normal with the correct timing , and a good engine.

to find leaks with no damage use propane gas ..attach a hose to a small torch head and with the gas valve very low in volume aim the hose at the areas to be tested..carb cleaner will damage all rubber parts so try to keep it only on the metal...

you stated it runs rich this then means that the carb float settings need be checked and the bowl/needle valve,seat be cleaned or replaced.....

[010175]

Thanks J cat, I assuming that when testing, the raw propane gas when ran around the carb on a running engine should be sucked in the leak and you will see it? I hate to beat a dead horse but I would to know, with air adjustment screw turned all the way IN, the engine still keeps running just like it was 2 turns out. Is this normal or should this kill the engine with the air adjustment all the way in finger tight? Thanks for all your help in the past 5 years. Dave

[manicmechanix]

What model of Carter is it? I don't think adjusting the idle air screw all the way in would kill the motor. Engine should still be pulling some air from the PCV assuming you are running one plus around the throttle butterflies. Closing the idle misture screw should kill the engine though I think.

[j cAT]

Originally Posted by 010175

Thanks J cat, I assuming that when testing, the raw propane gas when ran around the carb on a running engine should be sucked in the leak and you will see it? I hate to beat a dead horse but I would to know, with air adjustment screw turned all the way IN, the engine still keeps running just like it was 2 turns out. Is this normal or should this kill the engine with the air adjustment all the way in finger tight? Thanks for all your help in the past 5 years. Dave

when the propane gets sucked into the engine you will get a rpm rise...so with a tach and the propane you can direct the propane at any area to search for the leak with out any carb cleaner damaging issues...

the air screw adjustment I'm just not sure ...I don't think I ever required that this be adjusted...

but the running too rich should be the float adjustment or new float valve/parts/cleaning...

some engines require that the idle mixture screws be adjusted at 800rpm...then you adjust each screw for a 50rpm drop ...called the lean drop adjustment...

these screws are removed cleaned and reinstalled ...screw in till gently bottoms out then CCW 3turns...then do the lean drop adjustment according to your manual instructions...using a vacuum guage is also helpful ...

[maxwedge]

Pull the carb off and make sure the prim. and secondary throttle plates are seated/closed completely.

[010175]

Thanks to all you. I will pull the carb and check it out, then run a leak test next week.. Dave