Timing driving me nuts

[Suicidalbadger]

Long story, but bent a valve a while ago, had head sorted and cams clearances measured and shims sorted with a few new valves. The valve guide had cracked so needed some work I couldn't do.

Now putting it back together after two years in boxes, went to start it and timing was way out, like crazy backfire, hot exhaust, really rough. Checked everything twice, DMC2 ignition seems to work but middle and right spark plugs have a weak spark so maybe new plugs. But it just won't run timing seems so far off.

The marks on the cam sprockets are straight up when outside cylinders are at TDC, so cams should be right but it almost seems the sprockets are on the wrong holes it's that far off running. One of the marks is very feint on the sprocket but it's the only mark,  I've had cams off before and never a problem before so I'm not new to this type of work.

Does anyone have a picture showing both camshafts position of Inlet and exhaust lobes/cams at TDC on flywheel? or is there anything else I've missed? it was running fine until valve bent and even then drove home on two cylinders.

Thanks I hope someone can suggest something I've missed.

Badger

 

[sfcpiet]

With the crank at TDC, the cam lobes should roughly point at each other, sort of laying flat on the followers, on one of the outer cylinders, doesn't matter which.  Exhaust is just about to close, inlet is starting to open, rather symetrical, good enough for a rough check and should at least start and run with this set up.

piet

 

[Suicidalbadger]

Thanks, it's what I thought, been turning crank slowly and it all looks good. Some overlap with exhaust open as inlet opens before intake. So cam lobes are pointing towards each other but downwards in a shallow V. sparks are poor on two plugs so maybe they aren't working under compression, so new plugs ordered.

 

[Dellortoman]

... as inlet opens before intake.

There's your problem.  Can't have the inlet opening before intake

If you doubt the accuracy of the timing marks on the camshaft sprockets, then the only way to be sure is to ignore them and dial the cams in with a degree wheel.

 

[Suicidalbadger]

I was starting to think that, not something I really wanted to do and can't fathom out how it's gone together in the past with no problems.

Somewhere I found a table of valve opening angles, or max open crank angles to check.

If someone has a good photo showing relative positions of both cranks that would help me decide this is the next step.

Thanks for the help.