Practically Classics Forum

Hi,

I bought a full rebuild kit for my spitfire 1500 twin HS4 carbs plus new needles, I started by stripping the carbs did a really thorough clean (took hours) and rebuilt using the new parts:

new spindles, butterflys (without overun valve), jets, needle valves, gaskets etc etc

I put the car back together and after some tuning with the gunson got a nice blue colour which was unachievable before the rebuild, I balanced the air intake with a gunson carb balancer which i got spot on.

my issue is.... when i apply the choke it operates correctly and pulls down the jets however when i put the choke in the jets dont return up fully causing a rich mix, is it possible to lubricate them with anything? ie vaseline, grease 2 in 1 oil or similar as they are new they seem quite tight which is contributing teh the issue.

ALSO

I drove the car after the rebuild and when the car was warm and im getting a lumpy acceleration sounds more like a raspy noise rather than a smoooth pickup, my plan is to once again check and clean the spark plugs, check igition timing, check valve clearances anyting else may be causing this worth checking?

cheers guys spent so much im on the car and never actually used it which is getting demoralising so any help much appreciated.

cheers
Joe

Is your choke return spring OK? Usually they are attached to the linkage somewhere on twin setups.

Hi, yes the choke spings are both working fine and without the jets attached offer alot of reistamce when you operate the choke maulally and return with a snap, its just when you attach the jets the whole setup doesnt return fully indicating either an issue with the angle of the setup ie not pulling straight up or the jets being quite tight in the 'hole' on the bottom of the carb.

when you look into the carb from teh air intake you can see the top of the jets are level with the bottom bush when you manualy push the jets all the way up

it's possible the replacement jets have been made a few thou over size or maybe the old jets have worn a slight ridge in the guide bore , might be worth measuring the new jets to make sure