Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing tuning SU HS6 carbs in a '67 +4?

Thanks for all the info. I also found a Youtube of MossMotors showing how to connect the hose to the bottom of the float bowl... Is the install of the jet just as simple as a screw as noted by the diagram?

Yes, although it helps to hold the choke on with one hand to push the lever fully down for better access.

Ok... This past Sunday I installed the two new jets and it was a piece of cake. One must be patient and have the right tools of course. I had to have a phillips head screw driver with a bend, or use a removable phillips head drill bit. It went in like a charm. No more leaking gas (petrol). It did run, but now I have to re-tune the carb to get it done right. It seems to have taken away the sputtering, but I will have to see how the tuning goes. That will have to wait until next weekend. Thanks for everyones two cents.

Great to hear. Let us know how the running goes please.

OK... over the weekend I adjusted the carbs and went for a little drive and I have eliminated totally the sputter. It was the leaking jets that obviously messed up the fuel supply and the engine was just sucking air at the higher revs. Thanks for all the good advice. I think noticing that the hose to the jet was wet with gasoline (petrol) really was the giveaway hint to the problem. I changed the spark plugs and noticed one wire was a bit loose to the plug. I did get some sputtering tiny backfire pinging at times. Could the loose plug have caused that?
Learning all the mechanics is good fun. I have been watching a lot of Moss Motors and University Motors Youtube videos.

Good news you have got your issues resolved.
As far as a loose connection to the plugs is concerned, yes that is a likely source of such issues as misfiring, spluttering and backfiring.

Well done! Very satisfying eh?

Loose plug leads can short under load - pulling hard in a high gear for example, so it might have been that.

+1

Was there pinging as well as backfiring, the pinging may be caused by your timimg and you may just need to tweak that as well

Yes, the pinging - well um... i'll try to describe it... It only happened when slowing down.. I believe in and out of gear. It wasn't anything horrible, but it would be a slight "pop",,,,"pop".... very low popping noise, as if it is almost backfiring. I'll now order new wires and distributor and see if that helps. I call it pinging.. cause it is sort of small... It never popped while pushing the throttle.

Thanks.