carter "N" issues (Photos)
 

I've got the carb off the 63 O apart and even though I was extremely careful in removing them, I managed to shear off the heads of two of the small brass screws that attach the butterfly to the choke and throttle shafts.

I guess I'll drill it out and re-tap for #4 hardware, if there's enough material there.

Anyone been down this road before me?

I knew they were fragile, and likely "staked" to prevent them from backing out. Once I got them loose, I backed it out a half turn, then forward to clear the treads, then another half turn, then forward, etc etc. Even so, the brass has very little strength (particularly after years sitting out in the rain) and even though I was careful, the heads sheared off on two of them (naturally, one on each shaft!

One step forward, one step back...

OTOH, the carb, though filthy, is cleaning up nicely

John

I had one of the screws break off on my throttle shaft. One thing you can try...if you can get the shaft in a real good work holder on a drill press, and use a tiny bit, you may be able to drill out the brass screws without even touching the threads.

I tried it but went a little too fast and the drill deflected, so it did hit the threads. I wound up just swapping out my throttle shaft, but I'll still probably drill it out for #4 screws when I rebuild the K321 that I borrowed from.

Good news
 

I put the throttle shafts in a V block and was able to drill a VERY small hole down the middle of both screws. I then sharpened up a scribe and used a small hammer to collapse the shell of the broken off screw enough to push it out of the bores of both broken off #3 screws without zinging much of the existing threads.

All I need to do is get some #3 hardware and some locktite and I'm back in business. I'm really glad to be able to get this 50 year old carb back to work.

John

PS: If I'm right, I will need to figure out how to get a little ball bearing to stay in position under spring tension while I slide the brass shaft back in ...can't remember whether it's the throttle shaft or the choke. I can see where it indexes on a detent on the shaft, so I guess it's the choke (Im not near the carb to check).

The detent bearing is for the choke.

I'll assemble that in the tub*, with the stopper in and the shower curtain drawn , so that WHEN it goes vectoring off into space, it won't go far.

Sounds silly but it was a great location to assemble the small parts on an AR-15 I built up from a kit.

John

* EMPTY tub.

The referenced bushing does NOT fit an "O" carb type N
 

Got some of the bushings mentioned as fitting cub carbs, and they don't fit the Original Carter N carb. The OD and ID are both too big to fit the "N" carb.

I should have measured it before driving 12 miles to the one Ace hardware that had these bushings. I guess I'll keep them for the other Cubs.... Rats!

John

I hate hearing that was a wasted drive on your part, but is good info to know. I didn't know there was a difference in them. :angry:

not all wasted...
 

Well, I was able to get some 3-48 hex drive ("Allen head") screws there, so it wasn't a total waste. I much prefer attaching fasteners (particularly small ones) with an Allen head than a flat blade anyway. I fit them in by hand last night and my drill-out surgery was successful, as they threaded right back in. Whoo hooo!

I'll get t calipers and the fastenal catalog out and see if there is an appropriate size bushing available for the "N" carb so we can add this info perhaps to the Tech Library for the next person down the road...

John

ended up making one
 

Made one on the lathe, even with my crappy machinist skills :-)

For the Carter Model N bushing

OD= .405"
ID= .216"
Thickness= .100"

Great job on that. :beerchug: