Blocked idle jet on monobloc 389?

[KiwiGF]

Hi,

Quick question (I hope), finally after nearly 2 years of buying my 56 A10 non runner I have got the rebuilt engine started, but it "dies" almost immediately unless I keep pressing the tickler every second or so and hence the carb flooded, I've cleaned the brass idle jet but no improvement. My question is, should petrol come out of the idle jet when it's little brass cap is removed? (it's not coming out, and I'm thinking maybe the petrol feed to the jet is blocked, or the float level wrong but I don't know how that could be).

It's got a 1 1/8" size 389 with 25 idle jet (I think ideally it should be 30).

I've not seen the oil return to the oil tank yet but that's another issue to be sorted. I think the return filter is taking time to fill up or at least I hope so.....


Edit - forgot to mention, I've blanked off the choke cable cable hole in the carbs top cap, and not fitted the choke slide and spring, so I've assumed it's OK to do this (and there is no difference between throttle slides when a choke slide is not fitted).

[wilko]

It certainly should leak out. Must be blocked, or the mesh filter hiding on top is.

[KiwiGF]

Thanks Wilko, I'll give the carb (yet another) clean out tonight.

I got it going long enough to get the oil returning to the oil tank last night, it sure was a relief to see that, in hindsight I should have loosened the pressure reducing valve nd kicked it over until oil came out of that, and saved myself some anxious moments!

[chaterlea25]

Hi Kiwi,
Also check the tiny holes in the body/jet block where the pilot mix enters the inlet tract
one hole is under the inner edge of the slide and the second nearer the engine side
Yes, fuel should dribble out when the cap is removed, the jet should be screwed fully home before the cap is fitted

Well done on getting it running at last

HTH
John

[Rgs-Bill]

Idle pilot jet hole in floor at the back of carb venturi is either blocked, or no fuel is getting there past the jet bloc, from the float bowl.  Or air holes going through from front of carb, (air cleaner off ) through the jet bloc, into the 2 holes in the carb body itself, where the idle circuit adjustment screw adjusts the idle.  The horizontal one, has somehow managed to plug up, ( does not hardly ever happen )

[KiwiGF]

Thanks everyone, it's starting and ticking over perfectly now after I found and cleaned all the mentioned places. I've even fixed the flooding problem after using the cling film and rubber technique in place of the side bowl cover and letting the carb fill up whilst I watched the float.

I was very surprised that petrol started coming out of the tubes in the inlet mouth well before the petrol level in the bowl had reached that far up and the float valve had not stopped the petrol either, it turns out the tickler doubles as as an air vent to the bowl and the bowl was getting pressurized and petrol being pushed out of the jets backwards I guess.

Anyway it was a 2 min job to clear the vent holes in the tickler and now no flooding and no need to buy new parts.

[wilko]

That's why i like monoblocs!