H2 carb float bowl orientation

[DaveAhrendt]

Are the arms on the float bowls supposed to be perfectly perpendicular to the carb body? I suspect they should be
but mine are not. I'm guessing this is leading to the difference in fuel level in the jets.
Thought I'd ask before I create some new leaks.

Thanks,

Dave
'46 TC 0524

[Steve Simmons]

So long as they are equal to each other, I don't think it makes a lot of difference. Moving them can change the level a tiny bit though, so if you move them then you might want to just check the level. Some people run them as far away from the exhaust manifold as possible just to get them away from the heat. I don't go quite that far because it can make it difficult to get the lids off.

[Duncan M]

Moving them does effect the fuel height in jet. Something to keep in mind when adjusting fuel height in jet.
page 29
https://www.namgar.com/images/uploads/C ... er30.1.pdf

[DaveAhrendt]

OK, I'm confused. I found a reference in the NEMGTR tech reference that the arms should be as close to perpendicular to the carb body as possible. I have done that. I've set the float levels using the 7/16 tube in the SU tool kit. When I turn on the fuel pump runs until it stops. When I check the fuel level it's way below the recommended level of .220'ish below the jet bridge. In the case of the front carb I don't start to see fuel in the jet until it's almost completely lowered to somewhere around .43'ish. On the rear carb I don't see fuel at all since the arm stops the jet from lowering much below .4.

I'm not sure what I'm doing wrong here but the level seem to be almost half of what I should see. I think I've got all the right parts, float fork, etc. Any ideas?

Thanks,

Dave '46 TC 0524

[Steve Simmons]

I'm not an expert, and I change my method every couple years as I find better ways, but currently what I do is set the jet 60 thou below the bridge and then adjust the float height until the level is where I want it, ignoring the measurement of the fork. If the fuel level is too low, I'd raise the float level no matter what the actual gap is. Sometimes the forks get tweaked, or you could have a needle valve that was made too tall. Lots of variables.

[Duncan M]

Dave, you need a smaller diameter tube for your preferred adjustment method. Sounds like one of those very small dia. cocktail straws might be what you need. The fuel level in the float bowl is directly related to the fuel level in the jet. When I switched to the nitrophil floats, I recall it was tricky getting them adjusted so that the fuel level got high enough.

[DaveAhrendt]

Thanks for the info guys. I've just come in from the shop and things are not well here. If I start reducing the diameter of the test rod the fuel level in the jet does rise accordingly. But, to get close to the .220 below the bridge the fork is almost flat and I think the nitrophil float may actually be hitting the fork pivot. This is with a .25 drill as the test rod. Something is awry.

Are the nitrophil floats that much different in floating characteristics? I guess I can dig out the old brass floats and see what happens.

I had a plan to install my Shorrock supercharger this fall/winter with a newly rebuilt carb from Joe Curto. Maybe I should just up my schedule and do it now.

Dave '46 TC 0524

[Duncan M]

As Steve mentioned there are a lot of variables, like a shutoff valve that is too long in length. Another problem with the valve can be not using a gasket or using too thick a gasket. Does it call for a gasket? And of course the forks can get all bent into odd shapes.

I found the correct length original type (needle) shutoff valves are a bit different length from the newfangled Grossejet (ball) valves. I found using one or the other with the nitrophil floats allowed the proper fuel height setting to be achieved. Sorry, cannot remember which. Also, some newer forks I got a few years back for the TC carbs were a bit different than the old ones that were in there. Again, I do not recall which ones ended up working to get the fuel height high enough.

When you go by the method discussed on page 29 here https://www.namgar.com/images/uploads/C ... er30.1.pdf
the fuel height will be .250" to .1875" below the bridge. Note that on page 29 to get a value below top of bridge -- you need to add the jet drop (1/16 inch) to the fuel height 1/8 to 3/16 inch below top of jet.

Pitstop today in TC9866/exu Note the red foliage poison oak in background.

[DaveAhrendt]

Thanks for that info Duncan. I was away for a few days. I did check for any floating difference between the brass and nitrofil floats. Both float the same in a jar of fuel. Both sit somewhat unlevel at 50% below the fuel level. So there should be no difference in performance.

While we were away I decided to ditch this effort and start installing the Shorrock. I was going to do it later but why wait.
Thanks again,

Dave