Does anyone have the valve timing in degrees for the 3HW engine, please.

I have all the other timings of the period, but seem to have misplaced the 3HW timings -
The cams are timed up as per the WD manual, but at sometime in the near past the exhaust valve has taken a divot out of the piston ?

A serious clout, yet the valve is still straight - considering the valve is at 90deg to a flat top piston!!!??

Now, she is either not burning any oil whatsoever (+600 miles) and the damage was done prior to my ownership, or i'm responsible ?


I have also checked the timing using pre-war 3H degrees, the Inlet is bang on, but the Exhaust looks about 1.5 teeth out ?


There's also a faint mark from long ago, on the inlet side ?
Surprised that things are so close on a low compression OHV engine?

I don't know how it could be 1 1/2 teeth out? But this is from my 3HW folder. I presume they mean 'Degrees' not 'inches'. Ron

email (option): ronpier@talk21.com

Thanks Ron - completely different from what i have, probably because these figure will be at a different checking lift (often 0.20" though Triumph have tended to us 0.040") ?


Wanted them in degrees as I've yet to measure a cam which actually conforms to what its supposed to be.
Using degrees you can work out where peak lift should be - these new figures are a good example.
Will sit down later and work out what it all means on CAD.



1.5 Teeth out - is the difference from what i have and what the 3H value should be .... based on 40 teeth on the cam wheel

Well any further info you work out I would also add to my folder. Ron

email (option): ronpier@talk21.com

interesting when look at these timings using CAD .... more questions than answers - the valve closed value (on both valves)is bang on my 3H info, however the open point is 28-35deg less, giving much reduced valve overlap?


The big problem is how the timing is measured, due to wear, lift ramps, etc. so degrees are usually measured from some value of cam of valve lift - usually 0.020" or 0.040" - this is not given in any of my info on 3HW engines, but Triumph have historically used 0.040".


I've another set of cams i'll slip in and measure, then publish what i find.

Well, my 'new' set of cams give almost exactly what RON's spec. say, i.e.;

INLET 47.5/68.5 deg
EXHAUST 69.5/46.5 deg

These are just opening values (i.e. ZERO lift).

The original set of cams came with the engine and i have no idea what these come out of as they do not even conform to the Tiger 80/70 timings of ;

INLET 36/70
EXHAUST 70/36

Presumably, again @ ZERO lift (from the 1939 Triumph Instruction book).

So, i will be eager see the difference.

Regarding the above book, it seems the final gearing for the Tiger 80 is the same as the 3H model, so unless the WD version (3HW) has much reduced gearing (smaller Engine sprocket and/or gearbox sprocket) - i guess she will get left alone?