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[Norm]

Does anybody know how firm the valve springs should be on a 1939 sidevalve 350 should be. Being able to open the valves with my finger just doesn't seem right lol

[Norm]

I should have added that this motor was in a fire hot enough to melt the half tappet door off

[Bullet Whisperer]

Hi Norm, I have one here. It's an engine which I stripped after it has lain outdoors for about 50 years, but the cylinder barrel seems quite good and has the valves and springs still in place. I will give the valve springs a press and report back later. Cheers, Paul.

[Norm]

Thanks Paul, this motor will not be going in a bike, it just has to end up as a running display engine, give it a start, let it choof away for a short time and everybody will be happy

[Bullet Whisperer]

Hi Norm, just checked and there are single springs in this one and with the barrel upturned, I can open the valves about 1/2" or so with thumb pressure, so yours might be ok. One thing, the valves are never going to hit the piston ! Cheers, Paul.

[Scalyback]

I would ask Guy Martin.



He did an excellent demonstration on finding tyre pressures by how much he could squeeze them!



We are not worthy...We are not worthy!

[Norm]

Thanks Paul, sounds about right, I guess gravity helps them shut and as the piston comes up the compression will help shut them. lol. Thanks again

[Norm]

Boy this motor had been hot, no oil in the pumps just crumble/carbon, and on the crank pin and conrod you could see where all the rollers had been sitting, quite amazing

[papasmurf]

Scalyback with reference to Guy Martin and tyre pressures. I suspect very few people could understand the frustration, anger, and outbursts of tears I have due to in the last few years losing my engineering "touch" with my fingers.
My father, (who had made wooden parts for Mosquito fighter bombers,) could never understand how I from a very young age could measure things accurately by eye and touch without the benefit of measuring tools.

[simon]

My cobber is rebuilding a 16H Norton at the moment and it doesn't seem to particularly powerful valve springs. It's only about 5:1 compression too. Amazing that they go so well.