Forum

[Mark M]

Walter, I had this problem when rebuilding a pair of Monoblocs on my Mk1 Interceptor. I wrote about it before. If you have used the new Viton tipped needle I would suggest replacing it with a brass one, the new design just would not seal on my carbs. I had to use the original seats as they have a larger fuel flow and Amal didn't (maybe still don't) make them at the time. I bought new Amal components for all the usual wearing parts and was not impressed, I found the bike ran better with the old needles, needle jets, fuel float needle etc etc re-fitted. Also, the new adjuster screws had screwdriver slots which were machined so small no screwdriver would fit them as well as odd shaped tapers on the pilot screws. They may have improved over the 4 years since but I think it's worth refitting a brass original float needle.

REgards, Mark

[Rattlebattle]

It's a while since I looked at mine, but is it possible that you have the little brass spacer positioned incorrectly on the float spindle thus restricting float movement? i.e. Is it on the wrong end? Away from home at the moment, so can't check if this is a daft suggestion or not but might be worth a look.

[Dutto]

Walter, the only way I can see the float bowl hitting the tickler before the needle is if the float is fitted the wrong way round. I know this is probably silly but it's an easy mistake to make.....

[Presto]

The only way the float can impinge on the tickler before the float closes the float needle is if the tickler has been fitted incorrectly or its spring has failed to return it to its seating. In terms of its vertical dimensions the float is symmetrical (but not symmetrical in terms of its horizontal dimensions – therefore there is a ‘front’ and ‘back’ difference but not a ‘top’ or ‘bottom’ difference). So fitting it the ‘other way round’ makes no difference.



The float may ‘catch’ on the lowest of the cover screw bosses, it may be affected by irregularities in the brass bush on the spindle, or on the spindle itself.



It may be worth trying the newer alloy float needle, which is both lighter and shorter than the ‘standard’ type – even though it may seem logically to exacerbate the problem Walter reports. The alloy needle is approx 0.030 shorter than the brass viton tipped needle. This has been found to make a difference to fuel flow in Monoblocs – allowing a slightly higher fuel level before shutting off fuel supply. The shorter, alloy, needle in the Monoblocs can result in cleaner carburetion at the point of transition from pilot jet to slide. This particular problem does not occur once the engine is running, as movement (vibration and tilting in cornering etc) counter any tendency for the valve to shut off prematurely.



But ‘bottom line’ is that if the tickler is fitted correctly and its spring returns it to its seating it is not possible for the float to hit the tickler before shutting off the fuel supply through the float needle.

[Dennis C]

Not possible unless someone has put a washer under the valve seat raising the height of it.

[Presto]

True Dennis - but the washer would need to be approx 3.5mm thick. But why would anyone put such a thick washer under the needle seat? It would always prevent the needle closing and the carb would perpetually flood. Or am I wrong?

[Dennis C]

No not entirely wrong, the amount of movement of the flat on the float were the needle sits is less than you think and just fitting a fibre washer to the valve is enough to cause this problem, people seem to think that this fitting needs to be sealed which is the cause of the problem, logic says it should be sealed but?.

[Presto]

Thanks Dennis – but my point I think still stands. If a washer [of whatever thickness] is fitted that causes the float to touch the tickler [when it's in its 'normal' position] before shutting off the needle valve then there will be a constant flow of fuel and constant flooding - not only flooding when the tickler is activated.

[Dennis C]

Sorry I am confused, isn't that what Walter was complaining about?, surely he wasn't complaining it flooded when he tickled it.

[Presto]

Dennis my thinking is on these lines:



Walter has said: “When I tickle the carb on my 1960 connie the carb just floods” and also “never had an issue then or before then so its a mystery why it's playing up now, any more thoughts?”



If the washer was the cause of the problem (and he hasn’t fitted a washer since he’s laid the bike up) the carb would have flooded constantly before he put it away, not just since he has ‘recommissioned’ it.