Tappets

[Rob Frankham]

I had a Matchless G3L single where the specified valve clearance was zero on a cold engine. The method was to adjust so that the pushrods would just spin with your fingers. I presume in that case the clearances opened up a little with a hot engine.

Excerpt from the Matchless G3L service manual (available on line at https://www.manualslib.com/manual/11424 ... s-G3l.html).

When checking the valve timing the tappet clearances must be set to ·014 inch ...



Rob

[barryh]

Excerpt from the Matchless G3L service manual (available on line at https://www.manualslib.com/manual/11424 ... s-G3l.html).

When checking the valve timing the tappet clearances must be set to ·014 inch ...



Rob

There were different versions and depending on whether they had steel or alloy pushrods some were zero clearance and some were specified with a gap.

[melville]

Excerpt from the Matchless G3L service manual (available on line at https://www.manualslib.com/manual/11424 ... s-G3l.html).

When checking the valve timing the tappet clearances must be set to ·014 inch ...



Rob

There were different versions and depending on whether they had steel or alloy pushrods some were zero clearance and some were specified with a gap.

Yes, the pushrod material is key.

Stock VWs use alloy pushrods and are usually set at .006". The alloy pushrods expand at a rate fairly close to that of the alloy head/iron jug. They are noisy, but the noise is consistent over the usual operating range.

Most aftermarket PR for performance VWs are steel and the advice is to set them tighter, all the way to a 'loose zero.' One supplier's material says that the different expansion rate is a feature--"When the engine is too hot, the suddenly noisy valvetrain is an additional signal."

I'm curious how Airheads behave with alu or steel PR over the operating temperature range, as I understand they have been supplied with both.

[enigmaT120]

I use feeler gauges on my R65 because my exhaust valves do tend to close up even after having the seats replaced. And I want to monitor the changes.

On my '70 Bonneville, I frequently use GSPD's method. Reason one, that bike doesn't seem to experience issues with changes. Reason two, a .002" feeler gauge is very difficult to fit into a properly set gap! The gauges are very flexible.

But my favorite reason is that it's really easy to test my clearance with the Click and Clack method. I don't know if those guys ever owned old Triumph motorcycles, but the intake faint click and the exhaust slight clack are easy to hear.

I have owned vehicles where I had to check the clearances with the motor hot. I hated that job. In fact I think my '81 Toyota 4WD pickup with a 22R motor might be one....