Unfortunately, a full UAT weighs in at almost 7 oz weight, nearly 1/2 lb which on a '44 sized aircraft is really excessive. Wish someone would make something similar with fittings for 3 mm fuel tubing, a normal sullivan type gas plug and about 2 fluid oz volume.

I have 200 or so flights on a JHH Sabre with a Green '44 using the Wren type felt clunk, without a flame out attributable to bubbles. I know Larry W has gone to using a lighter weight 'bubble trap' fashioned out of a little 4 fluid oz sullivan tank, but there still remains the undesirable added weight of about 4 oz or so.

I think I would maybe add a 2nd washer to the felt clunk, to compress the felt a little bit better, soak it in kero and shake it around a bit while pulling fuel through it to see if those tiny bubbles might not disappear. Make sure you have a large enough vent on the tank, perhaps 5/32nds brass, facing forwards to get a little ram air pressure. Works for me.

Cheers,