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Is This Possible?
Posted: Sun Aug 16, 2015 7:38 am
by Coyote
While changing the floats and resetting the float heights the other day, I noticed something odd. You might remember I had trouble getting the center cylinder to run.. Well when I removed the bowls, there was residual fuel in the left and right bowls, but the center was dry. Totally dry - like it never had any fuel in it.
Those familiar with the later 550's know the fuel feeds between the left and center carbs - then crosses over to the right from the center carb. How could I have fuel left and right and none in the center? In my mind, that's impossible. But it sure looked that way.
The motor is still apart. Waiting for son to come over and compress the rings while I drop the cylinders back on. I can do that job alone with the motor on the bench, but not in the frame.
Re: Is This Possible?
Posted: Sun Aug 16, 2015 10:33 am
by bill in okc
You must have made the right call to readjust the float levels.
Re: Is This Possible?
Posted: Sun Aug 16, 2015 12:31 pm
by Alan H
After a run, the middle pot/carb area is warmer than the outside two, so the fuel evaporates more?
The carb will get heat from the crankcase/gearbox as well as the cylinder. More than the outer 2 perhaps.
I've noticed that the middle pot on my K takes a bit more 'starting' than the outer 2 after being stood more than a couple of days after a run, so may be similar to yours?
I usually fire up on the starter and it takes a few turns to pump the fuel through I suppose, so if the middle floatbowl is empty and the outers not quite empty, that would be logical (said Mr. Spock!)
Re: Is This Possible?
Posted: Sun Aug 16, 2015 2:32 pm
by tz375
eeze posseble fo sho.
If the needle valve is stuck or blocked on the center carb, fuel will flow over to the right carb and the center bowl will stay dry.
Re: Is This Possible?
Posted: Mon Aug 17, 2015 1:36 am
by yeadon_m
When fussing in the past with float heights on my GT380, I've carefully removed carbs after a run to find exactly the same fuel level in each bowl. So IMO, if you had a dry centre bowl, you have some kind of problem.
Mike
Re: Is This Possible?
Posted: Mon Aug 17, 2015 4:31 am
by rngdng
tz375 wrote:eeze posseble fo sho.
If the needle valve is stuck or blocked on the center carb, fuel will flow over to the right carb and the center bowl will stay dry.
Agreed. That's my bet.
Lane
Re: Is This Possible?
Posted: Mon Aug 17, 2015 4:38 pm
by Suzukidave
If the carbs are still off you could maybe do a bench test with the bowls off and use water instead of gas to see whats going on ?
Re: Is This Possible?
Posted: Mon Aug 17, 2015 8:08 pm
by Coyote
I'm surprised no one ever came up with Lexan bowls or even just a glass tube on the side. That would take all the guesswork out of it.
Re: Is This Possible?
Posted: Tue Aug 18, 2015 3:07 am
by rngdng
I've actually seen lexan bowls before. They were sold for a time but I guess didn't go over well.
Lane
Re: Is This Possible?
Posted: Tue Aug 18, 2015 7:24 am
by tz375
I have a couple of sets of Lectrons with clear float bowls.
Re: Is This Possible?
Posted: Tue Aug 18, 2015 7:53 am
by Suzukidave
A google search pulled up quite a few posts on checking fuel level on assembled carbs by rigging up a small length of model fuel line to the carb drain and then up the side of the carb bowl . When the bowl is full you can check the inside level by the level in the fuel line next to the bowl .
Re: Is This Possible?
Posted: Tue Aug 18, 2015 8:11 am
by Coyote
I've seen that method before. Easy enough to do, if and when you can ever find spigots to fit the drain hole threads. I have never seen anything even remotely close.
Re: Is This Possible?
Posted: Tue Aug 18, 2015 5:53 pm
by Suzukidave
Dont have one handy to check .. but would a main jet thread in ?