Ignition timing

[southerly95]

Just rebuilt front and top end of our 1098 but lost the timing, although I clearly marked the dizzy and clamp I forgot to mark the clamp to the housing. Started first time but tickover is a bit lumpy.

I have read and re-read Haynes on the timing job but it doesn't sink in on how to do it. Could someone help by explaining simply how to obtain static timing and then by using a strobe?

Also why does Haynes say in the engine spec that valve rocker clearance is 19 thou but 12 thou in the narrative on reassembly?

Thanks, John

[Willie]

The rocker clearance is 12 thou" so it was either a misprint or was referring to the special clearance needed when you are checking valve timing I do not know ! To set the ignition timing you need to set the timing marks(on the crankshaft pulley and the chain cover) to say 3 degrees before top dead centreBEWARE..you must ensure that this is when the compression stroke is on No 1 (radiator end) cylinder as it is possible to set it up on the wrong cycle. You can check this by feeling that both valves on no. 1 are unoperated. You then ensure that the rotor arm is pointing to number one plug lead and if necessary you have to reseat the dizzy to obtain this. Having set everything to this position you rotate the dizzy slowly clockwise until the points just open i.e.
a cigarette paper between the points becomes just free to move. the plug leads are fitted in the order 1,3,4,2 anti clockwise. The engine should now start ok but, all ignition settings are dependent on road testing. Final setting is arrived at for your engine by advancing the timing gradually until you hear pinking under acceleration and then backing off slightly

[bmcecosse]

Just swing the dizzy back and forth while it's idling (hot engine) and settle where you get smoothest idle! And then as above - make sure there is no pinking when flogging up a hill. You should check the vacuum advance mech is working - most are not !!

[southerly95]

Thanks for replies - forgot say there are no pints but a small box on the baseplate, do I need a light tell if the equivalent of the points are open if so how is it wired? Regards, John

[jojax64]

"You should check the vacuum advance mech is working - most are not !!"

How do you check it?

[bigginger]

Suck it and see - honest

[Matt]

errm if the engine is running dont worry about the static timing, just get the stobe on it as described above!

[alex_holden]

Thanks for replies - forgot say there are no pints but a small box on the baseplate, do I need a light tell if the equivalent of the points are open if so how is it wired? Regards, John

Connect a small 12V lamp across the coil. When the lamp goes out, the electronic points have just opened.

[bmcecosse]

Smootheset idle is the best setting! Otherwise you are just setting 'blind' against some fanciful setting in a book which was written many years ago when petrol had lead and octane ratings were high!
Yes - suck the vacuum pipe (be ready to spit!) - if there is no resistance then the diaphragm is bust, if there is resistance then you need to observe inside the dizzy to see if the baseplate moves as you suck.

[downsey]

I agree with bmc, just start it up and adjust the dizzy to the best idle. A-series motors run great when timed right, but never run horrible unless the advance is drastic. What i did was left the bolts a little loose and took it up some mountain roads continually stopping to dial the timing in.