TOPIC:

Folks a bit of guidance required..
(i've got the PDF manuals and have doen some searching on here, but...)

On my '79 A1 carbs, couple of assembly questions;

i)My idle screws (the little o-ring jobbies) seem to turn very freely along their entire length, zero to 3 1/2 turns out.
The springs all look the same length (approx seat to tip of needle end)
The o-rings all look undamaged / no cuts or chunks missing on close inspection.
I'm concerned they'll just vibrate-rotate like crazy, what's supposed to give them some stiction, the spring or the o-ring, or just the 'paint' marker the manual mentions?

ii)Float level checking; what & where do you guys get your drain screw adaptors?
My float bowls are downward facing drain screw, which mic' up to 5.9mm OD threads, so for metric I assume means M6 and probably a fine pitch?
There's no boss or stub to push any fitting on, and the o-ring is not clamped radially (i.e. no internal plain-bore) but rather in a longitudinal washer to boss manner, so no way to push in a tube.

iii)Float level; is the manuals' 6.5 - 8.5mm from machined flange correct, or any anecdotal recommendations on that?

Thanks,

Richard.

what's supposed to give them some stiction, the spring or the o-ring ?

Both the o-ring and the tension provided by the spring keep the needle in place.

Almost every set of carbs I have rebuilt have had this same issue. The OEM o-rings shrink, despite feeling viable. This included my own several years ago. Subsequently no o-ring resistance and that suggests a poor seal.
I came up with this solution and it works. Very well ! Small diameter silicone fuel tubing (R/C airplane engines) found at most hobby-shops - generic - ( Stan - note the lack of CAPITAL letters! )
Making them individually was problematic as I could only get 1 to my satisfaction out of every 2-3 cut. Then came up with a "cutter" that makes 6 at a time and all usable !
A "smear" of silicone grease and they turn in easily, seal perfectly and add that needed resistance.
They do not come in contact with fuel ( not supposed to be fuel in this area) so last a long time.
The socket-head conversion to the mix-screws is worth it's weight in gold !

Scotch I like that, silicon tube is a good idea!

Oversize but highly compressible, good thinking.

My box of o-rings doesn't go down to this size anyway, and actually the silicon may be a better way of achieving a very snug fit whilst still allowing rotation, whereas the harder o-ring rubber is much more critical to diameter.

From my R/C days (Stan cover your ears) silicon is fuel proof anyway (or at least for the nitro in those engines) so doubly ideal.


As much as I'm impressed with your mass-production tooling, I'll go the Edward Scissor-hands machete route, given the price of silicon!

Much appreciated.

When I see 'carb' in the title I just click to see, haha
Great info again, and I got to see your automation tool! Nicely done!

I'll suggest you use a new/sharp box-cutter blade or similar. Scissors create their own problems with this task, but a very small/very sharp machete would certainly add some excitement to the job!

: )

I will confess, my machete is presented in the form of surgical scalpels. best small knives I've ever bought, and range of blade types is handy.

Yesterday I was even using the poor things for deburring brass tube for the choke tube repairs and missing jet, not quite the use the blade designer intended I'm sure, but boy does brass carve nicely!