Timing Tips

[jonnyconcrete]

Replacing the dizzy on Saturday, so I'm after your timing tips!

[billwill]

Are you used to doing it?

The full procedure is something like this:


See the other threads for finding the correct one of the two top dead centres of cylinder 1 (the front one).
elan-plus-f13/tonight-three-newbie-questions-t20949.html

Use a socket set spanner & long tommy bar to rotate the engine , always rotating in the normal forward direction. Get it on TDC, then you need to set it to 12 degrees before TDC, but do not turn the engine backwards to do that, Go right around, two whole revs less 14 degrees. Very difficult to see what you are doing with the radiator in place, so be prepared to go through all the hassle of taking the rad out. When you have it in position put it in gear & put the handbrake on to make sure the engine stays at 12 degrees. Check after doing this as putting it in gear may move the engine a little. If it has moved start again


The centre shaft of the distrubutor rotates about a quarter turn as you slide it in, so you may need to try a couple of times to get it lined up with the distributor cap in the ideal position (which is roughly with the leads parallel to the engine block.

Finally with a lamp or multimeter or other suitable continuity indicator, rotate the dizzy body too & fro until the points JUST open at this 12 degree position. Then do up the clamp, put the rotor arm on, the cap & connect to plugs etc.

Put the rad back fill up with coolant and then you can try start the engine.


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You can abbreviate this if the existing dizzy is in the right place already by getting engine to TDC, then take the cap off and measure very carefully the position of the rotor arm and the contact connector, relative to some convenient fixed point on the engine. Unclamp, & lift out the old dizzy carefully noting how much the dizzy shaft turns. With care (& several tries) you should be able to get the new dizzy into exactly the same position.

Have fun!!!



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Revised to read 12 degrees after checking the Manual.

[oldelanman]

A comprehensive reply from Bill as always. Just a couple of points I would add....
It's a good idea to set the points gap on the bench before you put the distributor in - far easier than trying to do it on the engine. Also hold the distributor shaft clockwise (against the normal direction of rotation) when you are setting the timing to take out the backlash in the drive gears.

Regards,

[512BB]

And a point that I will add is this. You cannot hope to get your twink to run as it should, unless the dwell angle is right. For this, you will need a dwell reading device. The dwell angle is the time, in degrees, that the points are closed during the ignition cycle, and allows full build up of energy in the coil for a good spark at all engine RPM. Without the correct dwell angle, your lost.

Leslie

[billwill]

But you can't really alter the dwell angle, can you, except partially by varying the points gap, because it is determined by the shape of the top cam on the distributor.

You can use a dwell meter to adjust the points gap, instead of using a feeler gauge I suppose.

Does the manual show the designed dwell angle?

<later> ah yes it says "cam dwell angle" 60 degrees plus or minus 3 degrees.

[CBUEB1771]

You can use a dwell meter to adjust the points gap, instead of using a feeler gauge I suppose.

The dwell angle is what counts electrically. The points gap is only a proxy for the dwell angle. You use the feeler gauge to establish a starting point and then tweak the setting using the dwell meter to get to what matters, 60 +/- 3 degrees. I was always envious of Chevrolet owners as these distributors have an external points adjustment so you can zero in on the dwell angle while the engine is running. Of course that is just about all that I was envious of with respect to Chevys.

[Galwaylotus]

Set the dwell first. This governs the time the coil builds charge. The dwell setting also affects the timing - the reason it must be done first. The points gap is what sets the dwell. A 12v bulb with a couple of leads soldered to it will tell you when the points open so you can get that exactly where you want it when setting static timing.

[jonnyconcrete]

Thanks for all the tips Guys, much appreciated, has anyone used timing lights with an advance indicator..are they accurate?

[paddy]

has anyone used timing lights with an advance indicator..are they accurate?

I have a cheapish strobe with an advance adjustment - ie you dial in the advance you want, and then try to set the timing so that the timing mark is at 0 degrees.

I've never found it to be better or worse than the type of strobe with no adjustment. Although in theory you can set it to the desired figure in degrees (ie and not have to guess some position between the 10 and 15 marks), it doesn't add any more precision in practice, and just seems to me to be something else to go wrong. Also, as you wave it around in the limited space in the engine bay you can knock the dial and then you have to start again.

So, to summarise: I wouldn't bother.

Paddy

[summerinmaine]

has anyone used timing lights with an advance indicator..are they accurate?

I have a cheapish strobe with an advance adjustment - ie you dial in the advance you want, and then try to set the timing so that the timing mark is at 0 degrees.

I've never found it to be better or worse than the type of strobe with no adjustment. Although in theory you can set it to the desired figure in degrees (ie and not have to guess some position between the 10 and 15 marks), it doesn't add any more precision in practice, and just seems to me to be something else to go wrong. Also, as you wave it around in the limited space in the engine bay you can knock the dial and then you have to start again.

So, to summarise: I wouldn't bother.

Paddy

Agreed, as a general matter.

But I once had the opportunity to use a high zoot strobe with advance adjustment down to 0.5 degree IIRC, and the results were pretty nice with a freshly rebuilt dissy. Of course, the cost of the device would be prohibitive for all but the most well-heeled private owner.

[billwill]

The use of a timing light of course comes after you have done all the above procedures with static timing.

You need to do the static stuff first to get the engine running, then you can use a timing light for final adjustment and for seeing if the timing advances correctly at increasing engine RPM.


Trouble is the rad is in the way and it is very difficult to be able to see the timing marks with a timing light. Be EXTREMELY WARY if you still have metal fan blades on the water pump pulley.

[69S4]

Thanks for all the tips Guys, much appreciated, has anyone used timing lights with an advance indicator..are they accurate?

I've had one for many years and once I'd got over the gee-wizz hi tech (it was when I bought it!) aspect, I've often wondered how accurate the zero point was. Certainly if I set the advance dial to zero and then read the figures off the front cover, it's spot on tdc when I dial in the advance I just saw so I'd guess the dial is roughly right. Set on zero it seems to cross check accurately on some of my motorcycles where you set the timing with a dial gauge. IIRC it's a Gunson but I've no idea which model.