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Twin Dellorto's spilling fuel
FASTdan - 31/3/09 at 01:36 PM

We have a problem with our 40's where randomly one or two (on same carb) barrels will 'flood', causing a misfire and excess fuel to drip from the trumpet.

We've replaced the needles and ensured that the floats are free in their chambers and set both carbs with the same float height.

we've also wound the regulator RIGHT out and although I've not checked the pressure lately it cant be much - previously was around 3psi and thats before we added a return to the tank and wound it right out.

Can anyone offer any advice on this? What sort of float height should they be at - roughly as we'll be getting it set up at bogg's in the near future.

BillHoll - 31/3/09 at 01:40 PM

This may help even though it is for webers.

02GF74 - 31/3/09 at 01:50 PM

does this occur when stationary or when driving?

you are using correct spacers and thackery (or equivalent) washers?

which carb floods - the first one in line from the pump or other one?


also is the regulator working and have you adjusted it correctly?

FASTdan - 31/3/09 at 02:37 PM

quote:
Originally posted by 02GF74
does this occur when stationary or when driving?

you are using correct spacers and thackery (or equivalent) washers?

which carb floods - the first one in line from the pump or other one?


also is the regulator working and have you adjusted it correctly?


I think it has occured when driving but mostly stationary.

What spacers/washers are you referring to?

We've had it happen on both carbs - though they're not really in series as the T is in the middle.

Reg works as we've had a gauge on and seen the pressure reduce with the screw. Unfortunately my good gauge has just broken so the only thing i can put on now is a gauge measuring to 100psi (so tiny increments innacurate) and at the moment I can only get a reading if we pinch the return line so def not too much pressure there.

Canada EH! - 31/3/09 at 02:59 PM

Weber, Dellorto, Solex, and Mikuni carbs need to float on the manifold, too much vibration causes problems with the needle and seat.
Various means are used to dampen the vibration, springs on the bolts, large rubber gaskets between the carb and manifold, and a couple of others I have seen but can't remmember how they work.

FASTdan - 31/3/09 at 04:23 PM

quote:
Originally posted by Canada EH!
Weber, Dellorto, Solex, and Mikuni carbs need to float on the manifold, too much vibration causes problems with the needle and seat.
Various means are used to dampen the vibration, springs on the bolts, large rubber gaskets between the carb and manifold, and a couple of others I have seen but can't remmember how they work.


Ahh yes, I understand. We have a thick black spacer and also the spring washers (that are not totally nipped up - but will loosen a bit and see if that cures it, as I must admit the carbs feel pretty rigid).

cliftyhanger - 31/3/09 at 04:51 PM

http://www.sideways-technologies.co.uk/forum/Blah.pl?b-Del1/
has a useful float setting sticky for dellorto's.