Ax-man
Addicted to ArboristSite
I have been pondering this question for a long time and now that we here in the upper part of Illinois are in a deep freeze till the weekend I am going to throw this little brain teaser out onto the table. I haven't tried this but was wondering if it would work. Just want to see what someone else might say.
The question is . Can you test a carb for damaged H or L damaged needles or seats using an air pump like a Mighty Vac ????
Let's use a simple carb as an example that you have no history about where it has been or what might have been done to it, no priming system and no limiter caps to prevent you from turning the H an L screws all the way in till they lightly seat themselves.
Lets assume the carb checks out OK and hold pressure using the M/V on the pump side gaskets and the inlet needle doesn't leak.
Now to check for possible bad H or L needle or seat damage we remove metering cover and gaskets and the inlet needle and then reinstall the metering gaskets and cover without the inlet needle . Then we turn the H and L screws in till lightly seated or closed completely. Now we pump air into the carb . I am assuming air can't get past the metering diaphragm gaskets.
Now the answer to my question is this. If both H and L needle and seats are good they should hold steady pressure and not leak down . Correct or am I missing something ????? that would cause the carb to leak down and lose pressure by escaping somewhere else in the carb or hold pressure regard less of the condition of the needle and seats of H an L screws in the closed position.
I hope I am explaining this right and I am not way out in left field with my thinking by not actually doing this test on a sacrificial carb before posting it here. Just fishing for answers if any.
The question is . Can you test a carb for damaged H or L damaged needles or seats using an air pump like a Mighty Vac ????
Let's use a simple carb as an example that you have no history about where it has been or what might have been done to it, no priming system and no limiter caps to prevent you from turning the H an L screws all the way in till they lightly seat themselves.
Lets assume the carb checks out OK and hold pressure using the M/V on the pump side gaskets and the inlet needle doesn't leak.
Now to check for possible bad H or L needle or seat damage we remove metering cover and gaskets and the inlet needle and then reinstall the metering gaskets and cover without the inlet needle . Then we turn the H and L screws in till lightly seated or closed completely. Now we pump air into the carb . I am assuming air can't get past the metering diaphragm gaskets.
Now the answer to my question is this. If both H and L needle and seats are good they should hold steady pressure and not leak down . Correct or am I missing something ????? that would cause the carb to leak down and lose pressure by escaping somewhere else in the carb or hold pressure regard less of the condition of the needle and seats of H an L screws in the closed position.
I hope I am explaining this right and I am not way out in left field with my thinking by not actually doing this test on a sacrificial carb before posting it here. Just fishing for answers if any.