E3134 cam timing

Fast Eddie said:

Yes, they have the 3 keyways.

As I understand it, you can get within 2.5 degrees of any figure with this set up.

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1/3 tooth = 4.8 crankshaft degrees.

Correct LAB, so if you're 4.8 degrees away, find the right keyway and you'll be at 0. Worst case scenario is you're 2.4 degrees out, cos then by moving it, you'll be 2.4 degree out in the other direction!

+/- 2.4 degrees (4.8 degrees of movement).

I never use timing marks to set the cam timing - always degree disc and dial mike. And I get TDC with a soap bubble on an old plug with the electrode removed. I use nil tappet clearance for setting up and measure the error at each end and allow for it.

To each his own Alan.

Your method seems strange to me though. All recognised experts in this field suggest using a very large tappet clearance. If I recall correctly, the factory state .020”. This is because the initial opening and final closing of the ramps are not accurate. So, if you’re looking for opening and closing figures, you’ll be all over the place using zero clearance.

What figures do you use? If you’re trying to set to factory specified opening and closing figures, it will simply be impossible to do so with zero clearance.

If you use factory timing figures you must use factory stated checking clearances.

If you wish to avoid the unreliable readings of the ramps altogether, like Stan Shenton, and many, many others recommend, use lobe centre timing.

A friend of mine who has a works 350 Manx, tells me that measuring valve drop at TDC is the way to go. There is not much in the way of ramps on E3134s. The main thing is to think of valve openings and closings in the same way as you would with a two stroke where a mm in stroke height before the valve opens or closes, is a big difference.