Handitwin needle and seat not sealing

[mike-stroz]

I’ve been trying to get this ’40 or so Handitwin to run right for a while now but it just won’t. I put a new nitrophyl float in the carb and that seems to be working really well but gas is still leaking past the needle and seat and overflowing the carb. Is there any fix for this? Note that I don’t have any specialty tools, just hand tools. I did fit a new needle from a parts Sportwin I had collecting dust and it helped, but not enough to really make a difference

[pm-t2]

If you haven’t lapped the needle and seat, then I’d suggest you do so.

I make up a compound for lapping using toothpaste and Comet Cleanser. It’s not that aggressive, which is what you want when lapping in the seat in that aluminum carburetor.

You need a clean surface on both needle and seat in order to get the seal necessary to maintain the float level where you want it. You may have to also adjust your float height, which may be your actual problem. If the float is too high on the needle stem, it won’t pull the tapered cone against the seat area. Just sayin’

Hope it helps.

Best,
PM T2

[The Boat House]

Sent you a PM.

[mike-stroz]

quote PM T2:

If you haven’t lapped the needle and seat, then I’d suggest you do so.

I make up a compound for lapping using toothpaste and Comet Cleanser. It’s not that aggressive, which is what you want when lapping in the seat in that aluminum carburetor.

You need a clean surface on both needle and seat in order to get the seal necessary to maintain the float level where you want it. You may have to also adjust your float height, which may be your actual problem. If the float is too high on the needle stem, it won’t pull the tapered cone against the seat area. Just sayin’

Hope it helps.

Best,
PM T2

Ok, I’ll make some of that compound and try it out. I did think my float was set too high at first so I set it lower and same problem. I did a little more rooting around and I think I may have a spark problem too so I think I’ll replace the condensor and plug wires while I’m at it. For testing I think I’m going to put it on my ’46 Sportwin that’s a great runner

[mike-stroz]

Well, never mind about that spark issue, the points had somehow adjusted themselves to be constantly closed! This time I put loctite on the screw

[mike-stroz]

Looks like that trick worked and the needle and seat is sealing really well now. Not so much on my Sportwin carb now that I look at it… I’ll have to work at that one some more.

Tubs, I never got your PM for some reason

[The Boat House]

I’ll try again.

[mike-stroz]

Well, 10 minutes into testing the Handtiwin needle and seat and the fuel level hasn’t increased at all! There’s another project out of the way. On my ’46 Sportwin with the same carb it’s a whole different story. I’ve got no idea how it ran so well with the float bowl overflowing constantly… It’s looking like there’s some deep pitting around the seat, is there any way to bore out the seat slightly to get back to good metal? Or should I just find another carb?

[Author]

Posts