Rob's WD16H and Big4 Forum

One of first 500 of contract C14498 with leg shields

Rob's WD16H and Big4 Forum
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Re: cam timing 16h

Gents,

I am of the opinion that the picture of Heiko does not show the engine at TDC and therefore might be a little confusing.
When keeping the settings as specified in the original maintenance manual the cams should more or less be in the same positions.
That is how I have done it until now.
I am however game to try the setting John gave.
Modern petrol might require or allow for some change of settings.

The "military" setting always works and the settings on these old bikes are not as critical as on modern cars or motorcycles. There may however be another optimum after 70 odd years.

Cheers,

Rob

Re: cam timing 16h

Hello,

I have not done any further work on the engine since I took the pictures.

The manual says:
"Inlet open 27° to 30° before top center"

- so is this: Inlet is 100% open (I think so ) or starts to open?

"Exhaust closes 27° to 30° after top center"

- so this is: Exhaust just starts to close ( I think so ) or is it 100% closed?


This might have mislead me, what is now correct?

Thanks,
Heiko

Re: cam timing 16h

Hello Rob,

Thank you for your reply, please do you think my setting is ok ?

My TDC 1 is like fig. 14 p18 in the manual: In and Ex cams are parallels at 4 o'clock
My TDC 2 (after 360°) photo show exhaust cam begin to close and Inlet cam begin to open.

Any help is much appreciated

Re: cam timing 16h

This is what happens when you do not follow the instructions in the manual. It all gets very confusing and you end up making mistakes. To time the engine properly read page 18 to 20 of the instruction manual available for download on this site. It even gives instructions for when the marks are missing. (if marks are present do not trust them, people may have altered them over the years).
When you feel confident in knowing what you are doing then by all means experiment with whatever different timing figures you want but it will still be an "experiment".
The figures are Inlet starts to open 27-30 degs (5/16") BTDC
Exhaust fully closed 27-30 degs (5/16") ATDC

Obviously this refers to TDC on the exhaust stroke not the compression stroke.

The figures from Mike Pemberton only puts the exhaust 2 degs out of spec ie 25 instead of 27-30 so could be worth a try.