Classic cars forum & vehicle restoration.

[Brewster]

I'm a bit confused (classic understatement) about my 1967 Humber Septic and it's ongoing starting problems. I had it running reasonably well last year but then there was a loud bang, a puff of smoke and it refused to fire up again. I closed the lock-up door on it last year.

Back at it again now but it's still not running beyond a very rough 10 or 20 seconds now and again. At least one cylinder isn't playing ball. A compression test a couple of weeks ago showed 162, 162, 175 and 165 psi on cylinders 1-4. I had petrol dripping out of the inlet manifold overflow and a fuel gauge reading showed the mechanical pump was putting out about 4.5 psi. There's now a fuel pressure regulator providing 2 psi. When I try to start it I still get petrol dripping from the overflow.

I had the Weber 28/36 carb ultrasonically cleaned last year and replaced jets, gaskets, etc. I rechecked the float level of the Weber a few weeks ago. Although it's a Mk2 Sceptre, it has the 1725cc engine from a 1971 Sunbeam Rapier. It's a low compression block according to the engine number.

I set the timing last year to 10 BTDC and have just set the valve clearances when cold to a couple of thou wider than the manual says for hot. The plugs are constantly covered with black soot.

I'm at that horrible stage of having run out of things to try. Vacuum leaks? Is there a way to check with an engine that's not running? Any Rootes lovers able to suggest a way ahead?