Starting problems

S

steved1957

New Member
Hi, 3lt very difficult to start from cold, it will eventually run on tickover but won't rev, when it does eventually run normal it has plenty of power and really smooth.
It has a brand new SU Carburettor on it, inline fuel filter is clean, it has a good spark, fuel in the float chamber, i don't know a lot about SU carbs so would appreciate any pointers as to what it could be.
Thanks Steve
 
I haven't looked at that but will have a look tomorrow, as i say once it gets warm it runs sweet, plenty of power, it will start and tick over for maybe 30 seconds and then dies, i was beginning to think condenser, have one coming Friday will try that if i don't succeed before then.
 
Also check that the mechanical advance in the dizzy works smoothly, even when cold. Remove cap, you should be able to turn rotor easily against a spring, if not investigate - screw inside under the rotor might need oiling.
 
Bernd said:
There is oil in the carburettors?
Click to expand...
The damper only does something when the car is being driven. It slows dropping of the piston due a sudden change in manifold pressure, replacing an accelerator pump on conventional carbs.
 
sdibbers said:
The damper only does something when the car is being driven. It slows dropping of the piston due a sudden change in manifold pressure, replacing an accelerator pump on conventional carbs.
Click to expand...
In essence you are right, but it actually works the other way , it slows the lifting of the piston slightly when the throttle is opened, this means the depression on the jet increases and enriches the mixture for acceleration. Dropping of the piston is hardly affected at all.
 
Something inconsistent in the bit about 'once warm it runs sweet, plenty of power' and 'runs for 30 secs then dies' ?? Wont get warm in 30 secs AFAIK. Dies after 30 secs - choke still at full rich? Once its running choke should go in at least 1/2 way or more, just out enough to not stall. NEW SU carb - mixture adjusted by somebody who knows what to do ? Choke cable adjusted correctly?
 
I'd say you have two compounding issues. First the choke isn't set rich enough and second you havent checked the float level (or the needle and seat is too small or line blocked)
Engine cuts out because when running full rich on choke the float bowl is draining out. When choke is in, the lower fuel flow is sufficient to run the engine.
The crap starting part is a matter of getting the choke height and the choke/throttle cam setting correct as JP928 says. That task really should be done by a professional with experience on Su carbs as its kinda fiddly and is best done with specialist workshop equipment. Trying it at home can leave you with no hair and a car that won't start...
PS You can use a can of aerostart or flyspray to get it going till it'll run and you can warm it up enough to drive to the workshop.
PS2 take your old carb and any other bits you swapped with you to the shop
 
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wHAT MIKE SAID! Get a P5 3ltr workshop manual, it should spell out how to set up the Carb from scratch - the P6B manual does this well.
 
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