Runs lovely on choke but then... advice anyone?

Runs lovely on choke but then it stammers on pick up. Not sure what it might be.

Any ideas? Its already had a new distributer and carb kit.

 

I am far from an expert and its hard to tell without trying / hearing it, but it defo sounds like a air to fuel ratio issue, does the same thing happen when the engine is warm and the chokes are off but you are not moving ?

 

Ran fine before the carb kit ? , well if yes, you do the math

 

What carbs/engine are you running? if its stuttering on reving, check vac pipes if its vac distributor, also throttle pump if the carbs got one (this things job is to dump more fuel down the carb on take up of revs to allow the carb to catch up)

manifold air leak?
dirt in the carb (s)

any or all of the above, what has been changed setup wise from before?

 

if it's running ok on choke - therefore richer, i would guess it's fuel starvation under load if it does it while running.....presume you had it set up correctly? are the fule lines secure? filters clean?

 

Have you adjusted the dizzy or just plonked it in the same position as the old one?
Assuming your carb is fine and no air leaks etc etc, do static timing, then loosen the dizzy clamp and adjust slightly clockwise/ anticlockwise a bit until it runs well ( off choke) then go for a drive.

 

it sounds like its too lean

 

my 009 runs bob on too cant fault it i've just put an electronic ignition in mine and its fantastic i had a similar sounding problem with my '73 bay it was the coil breaking down under load..just a thought my advice dont throw money at it go through it mathodically, i know its frustrating but at least then you can be sure and cross of the usual suspects


hth

 

Mine wouldnt run correctly at all, wouldnt idle properly and used loads of juice. Whilst I was at T2 Detectives last week, they recommended I take it to a bloke in Wimpole Cambridgeshire, he detected that the carb was sucking in too much air due to incorrectly fitted butterflies and choke settings too high, hence it was running on choke great but ran like a sick pig when the choke came off. Couple of other carb faults. He set it up and then adjusted it under load using a rolling road. Increased BHP and top speed dramatically. Drove away like a new van, no flat spot on change-up and great acceleration plus strain free cruising at 75-80 MPH. Well worth the trip for me. Its much nearer to you so would be a possible option for you. 3 hours to fix a carb that mystified everyone else. Think it was Wimpole Garage Services and the guy was named Peter.

 

Add to the air leak list - the leak in the carburettor spindle - worn throttle spindle where the silicone put in by the previous owner falls out making the perfomance drift off with time.

Ours managed about 6000 miles after purchase before it got silly , with random acceleration flat spots and tickover trouble.
Once I got used to the Type 1 engine noises, I could hear the hiss on my carburettor where the air leaked in. I could also wobble the throttle spindle from side to side in the carburettor body. When I took it all apart there was a fair amount of silicone in there. Same kind of silicone that was trying to seal the rocker cover lids on where the cure was new springs which totally stopped the oil leak.

There are bushes for original 34 PICT-3 on Ebay - these carburettors have plastic bushes on the throttle spindle.

My Bocar had brass spindle bushes and these are about 0.1mm larger outside diameter than the plastic ones so the Ebay bushes dont fit properly without a little adhesive help. (some epoxy glue but there may be issues with heat softening it when the engine stands after running so I will be buying a new carburettor soon) . The Bocar has has nasty burred nylon mixture and idle screws which suffered after all the attempts to set it up with a wobbly throttle spindle.

Other issues that caused problems with the engine speed:

The cold start throttle end stop lever was jamming because one of the choke spindle bushes had been hammered in and was slightly crushed.

The copper rivets connecting the 12 volts from the tag to the bimetallic strip in the electric choke mechanism were loose so the choke worked sometimes - and so the choke would come back on by itself after a while. If you measured the electrical resistance while it was cold it was usually showing a good circuit.