55 100 BN1 Carbs

[Gray_Cat]

The float chamber lids on my 55 BN1 carbs have cutouts on each side of the hole for the retaining bolt. Are these to be unsealed? Are they for overflow? If so, is there supposed to be an overflow pipe? I've not encountered anything like them before so not certain about their function.
Also; what is best for gaskets when bolting the float chamber to the carb body? The original type or the rubber grommets that seem to be in the rebuild kits? Candidly, I tried the rubber grommets and they didn't work too well - maybe my inexperience? Any and all help very much appreciated! /ubbthreads/images/graemlins/hammer.gif

 

[Dave Russell]

On the type H carbs, the standard float chamber vent is a couple of slots cut into the top center flange. There is a sheetmetal cup with a side cutout that fits between the flange & the top hold down bolt. This cup is a larger diameter & allows vent air to pass into the float chamber through the slots.

There is also another type of vent that consists of a banjo with vent tube. The top is not slotted on this type of carb. The banjo is sealed to the float top opening with a special washer that has scalloped cutouts on it's inside diameter to allow air flow from the banjo to the lid. The top of the banjo is sealed to the bolt head with a standard fiber washer.

The float bowl attachment has several variations. They have different attaching bolts. The first type uses a brass washer with a fiber washer on each side between the bottom of the float bowl & bolt head. It uses a fiber washer between the bowl & the carb body.

The second type uses a different bolt with a steel washer & a shouldered Neoprene washer on the bottom of the bowl & a shouldered Neoprene washer between bowl & carb.

There is a third type that has a sort of headless bolt or hollow stud, threaded on both ends. This type uses a nut on the bottom, a steel washer next, & a shouldered Neoprene washer on the bottom of the bowl. Top of the bowl to carb has a neoprene washer & steel washer. The very top of the stud is sealed to the carb with a fiber washer.

My particular H6 carb uses the second type. No other arrangement will work. If you have the first type, the Neoprene washer will not work.
I have attached a diagram of the float bowl attachments.
D

 

[Gray_Cat]

Many thanks Dave. Your response answered my questions really well and I feel a lot better about working on the carbs. As far as I can tell the float bowls on my Healy attach as you describe in the first illustration. Also, the caps are missing for the float chamber lids so I will track a couple those down as well.
Thanks again!