Something's going on...
Posted: Mon Oct 09, 2017 4:26 pm
With my cylinder head. Engine has been going well, I thought, but has always had issues when starting from cold and a very slight stumble at very small throttle openings. When cold, the engine starts but misses badly with lots of spitting through the carbs and popping through the exhaust. After about 30 seconds or so everything settles down and the engine revs normally with no spitting etc., although the very slight stumble is still there. Have tried adjusting carbs as have others, but little improvement. A new engine man has just joined our local garage and I thought I'd give him a try. Must say I was impressed! He tried adjusting the carbs, using the tube to the ear method for balancing ( said he preferred that to using the any other method) and immediately noticed an issue with the inlet to no 4 cylinder. Reckoned not much wrong with the carbs, but thought there was a mechanical issue of sorts. Whipped off the cam cover, turned the engine to give cam lobe clearance at no.4 and found there was none To cut a long story short ( bit late for that ) I set about checking all tappet clearances and changing the shims as necessary. No problem there until I came to no.4 inlet. I calculated the the size of shim required (a bit on the thin side I thought) and replaced everything. Checked all clearances again and AGAIN no clearance at no.4 inlet. Tried again and by this time the shim thickness was only just above 50 thou.....too thin. I puzzled over this for some time (my few remains brain cells take their time to get together ) and realise the size of shim made no difference as the bucket was resting directly on the valve spring retainer !!! How the hell as that happened? I'm sure that all tappet clearances were fine when I first checked, though I did collect the head with camshafts already fitted. I do think that the original head machinist I used, topped some of the valves to give adequate shim thickness and maybe that has something to do with it. Anyway I've little alternative but to get the head off to find out what is going on. Anyone any ideas?
My new engine man is sure he can sort whatever it turns out to be, but I'm a bit annoyed with the original one.
Sorry, I've gone on a bit long. Once I get going...............!
My new engine man is sure he can sort whatever it turns out to be, but I'm a bit annoyed with the original one.
Sorry, I've gone on a bit long. Once I get going...............!