1946 M16 Cylinder Head

[clive]

The point i am making is that if the step in the bore sizes is an issue, as has been written about here numerous times, then go back to the tapered spacer with the addition of a tufnal one for heat isolation. Straightforward i thought.

[Diana3899]

Right Chaps, it's feedback time. With the new tufnel spacer in place I started her up from cold with a couple of kicks after giving her a tickle. Had a good ride around the Kent lanes without any problems and got her nice and hot. Got back to the garage, killed the engine and left her for 10 to 15 minutes and then tried to start her but she was a bugger to fire up. I had to give her a good tickle until fuel dripped from carb then with the exhaust lever lifted I gave the kick start lever half a dozen or more swings after which she fired up. So my theory that the metal spacer was causing the fuel to evaporate was clearly wrong! So I now wonder if the difference in hole diameters is causing the problem given that a 1" hole is feeding into a 1 1/16" hole which if my calculation is correct this will reduce the velocity of the gas entering the combustion chamber by 6.25%. I am seriously thinking of getting on to Surrey Cycles and ordering a new 376 carb with the correct bore. If I do go down that line will I need a 3/4" thick spacer with the appropriate bore hole. I would expect a hot engine to start without the carb being tickled! Any comments and suggestions would be welcome.