I had a similar problem recently with my 29 special. Having dismantled the engine to cure an oil leak I noticed a lot of backlash on the camshaft gears, so I sorted through my bag of bits and found two that meshed closer.

Although I eventually got the engine to fire, it would not run smoothly or pull well. like yours it had good(ish) compression. Working on the premise that I started with an engine that worked and now it didn't and the only thing I'd changed was the camshaft gear, I assumed I'd set the new gear with the timing marks misaligned. So I pulled the cover off and checked - dots aligned. I then got out the valve/cam/crankshaft diagram - whatever the proper name for that is - and compared the valve openings/dwells with the pistons. They were slightly out.

I then compared the fitted cam gear with the one I had replaced. The keyway/dots angle was about 170 degrees different! I always thought they were identical, although matched pairs. Obviously not. So, did you fit a new gear?

Rick

Location: Deepest Norfolk

You have my every sympathy John, at least mine has been persuaded to run and even to allow a couple of test runs of about 3 miles each.
I have terrible problems getting the engine to run and keep running. I suspect the float chamber level and am looking at that at the moment. When running the engine pops and bangs for a bit but then settles down.
I still have a screeching noise at times despite a new set of brushes in the dynamo and a check on the bearings in the (rebuilt) dynamo but the bearing is a new sealed one and seems to be ok.
I must agree with others that ignition timing is probably the key to our problems but its not easy getting to a satisfactory starting (no pun intended) point to make final adjustments.

Location: Near M1 Jtn 28

Location: Nottinghamshire

Reading back through the comments, I realised that in fact I have changed something.
Trying to remove the nut on the front of the crankshaft I foolishly stopped the crankshaft from turning by jamming a piece of brass in the timing gears with the result that the crankshaft gear was damaged.
I obtained a replacement gear and fitted it being careful (I thought) to get the gears in the correct place for meshing.
I need to check that out but am working on another possible problem, namely that the fuel level in the carb bowl may be too low.
The engine has started on a number of occasions but died after a second or two.
Instead of continuing to hijack Johns posts, I think it might be better to start a new one called 'Rebuilt engine refuses to start and/or run'.

Location: Near M1 Jtn 28

I have recently sorted out a bit of a brain teaser on a rebuilt engine. It started briefly but then would not restart, various popping etc. Re timed it and it fired but refused to run, rechecked timing fuel etc. decided on a push start, fired up for a second or two then stopped. Another push, kept seeming like it wanted to go, then no longer firing almost like the timing kept going out and then being correct again. The owner told me that he had replaced the dynamo distributer assy as a unit and the car had run perfectly well prior to the rebuild. However on removal of the distributer the drive gears were totally knackerd, after fitting a new gear in the end of the dynamo and swapping out the distributer the problem was solved. Just goes to show you can never make assumptions that something is correct or in good condition unless you have carefully checked it yourself.

Location: Auckland NZ

PROGRESS REPORT. Today Saturday 23/4/16. I have managed to get the engine running although I had to use spray easy start. She ran well firing on all four although on a rather fast tick over. I can now be assured that both valve and ignition timing are ok although possibly a little fine tuning may be required with the dizzy once warmed up. I obviously still have some minor problems with the carb or manifold leaking air but at least I know where the problem lies.

THANK YOU EVERBODY FOR YOUR TIPS AND ADVICE.


John Mason

Location: Nottinghamshire