Valve Spring Suggestion For Web 312a

Dan1950

Dan1950

1974 MK II Roadster
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Not looking for rpm above 7000, just want some added insurance against valve float.

Also valves probably std size.
 
Comnoz has done a lot of testing of valve springs. He would know. You could try a search on valve springs and bounce to see if anything comes up. I know he did some testing with the PW3 which will get the valves a bouncing at 7000 RPM.
 
Since you are on this topic...

I'd like to know what lifters (tappets) look like after hard riding when using a cam with violent ramps. I was looking at my old stock tappets and they have a very narrow witness line in them right at the center. I know valve bounce beats up the valves and seats, but that is going to happen anyway eventually. Was just wondering about the witness line being typical or not. This was with a Norvil 2S cam and KW dual springs.
 
Schwany said:
Since you are on this topic...

I'd like to know what lifters (tappets) look like after hard riding when using a cam with violent ramps. I was looking at my old stock tappets and they have a very narrow witness line in them right at the center. I know valve bounce beats up the valves and seats, but that is going to happen anyway eventually. Was just wondering about the witness line being typical or not. This was with a Norvil 2S cam and KW dual springs.
Click to expand...
The mark you describe can be valve float, ie the lifter is being ‘launched’ and then landing back on the cam.

It can also be due to the springs becoming coil bound.
 
Schwany said:
Since you are on this topic...

I'd like to know what lifters (tappets) look like after hard riding when using a cam with violent ramps. I was looking at my old stock tappets and they have a very narrow witness line in them right at the center. I know valve bounce beats up the valves and seats, but that is going to happen anyway eventually. Was just wondering about the witness line being typical or not. This was with a Norvil 2S cam and KW dual springs.
Click to expand...
My stock tappets had a slight witness mark in the center. That was with the stock cam. The cam lobes looked normal before I sent it off. All lobes and tappets looked consistent.
 
Fast Eddie said:
The mark you describe can be valve float, ie the lifter is being ‘launched’ and then landing back on the cam.

It can also be due to the springs becoming coil bound.
Click to expand...
Alright, kinda what I figured. Bounce more than likely. Coil bind I'm not sure is happening. I think the KW springs I was using were just stock replacements. Then again I put the springs in there a long time ago. I might have chosen racer boy springs. I did not do any custom spring shim work, I just used the stock parts plus the insulators.

This next bit will not go over that well. Just want to say it is not a complaint it just is. Could be user error.

I'm seeing the same thing on the exhaust valve lifter only using the JS2 cam and JS beehive springs no insulators under the valve springs intentionally. That might be valve bounce for sure, but I'm not seeing it at all on the intake lifters. This is looking at the motor recently taken apart after only 2K miles. I will be installing the valve springs with the insulators next go round. Lift is not that great with the JS2 cam, but it is not stock. I'll go check on the difference in lobe height from the stock cam in a bit when it warms up. Just for my own enjoyment. I know the 2S has more lift than the JS2. Different duration and softer ramps on the JS2 though. Checked that a couple of days ago.

Thanks
 
Dan1950 said:
My stock tappets had a slight witness mark in the center. That was with the stock cam. The cam lobes looked normal before I sent it off. All lobes and tappets looked consistent.
Click to expand...
Thanks Dan

I can't get a fingernail to hook up on the witness mark. (The redneck master mechanic test.) The witness mark just looks kind of scary. Wish I could remember if I had the tappets reground before I put that 2S in there. More than likely not, given where my head was at when I put that 2S cam in there. lol

The 2S cam surprising as it may seem, still looks good.

Looking forward to how you feel about your engine after you get it on the road. If JC likes that webcam, it's probably a good one and will be what you are looking for.
 
Schwany said:
Alright, kinda what I figured. Bounce more than likely. Coil bind I'm not sure is happening. I think the KW springs I was using were just stock replacements. Then again I put the springs in there a long time ago. I might have chosen racer boy springs. I did not do any custom spring shim work, I just used the stock parts plus the insulators.

This next bit will not go over that well. Just want to say it is not a complaint it just is. Could be user error.

I'm seeing the same thing on the exhaust valve lifter only using the JS2 cam and JS beehive springs no insulators under the valve springs intentionally. That might be valve bounce for sure, but I'm not seeing it at all on the intake lifters. This is looking at the motor recently taken apart after only 2K miles. I will be installing the valve springs with the insulators next go round. Lift is not that great with the JS2 cam, but it is not stock. I'll go check on the difference in lobe height from the stock cam in a bit when it warms up. Just for my own enjoyment. I know the 2S has more lift than the JS2. Different duration and softer ramps on the JS2 though. Checked that a couple of days ago.

Thanks
Click to expand...
Float is different to bounce. Float is when the follower leaves the cam. Bounce is when the valve bounces after being slammed back into the valve seat too fast. FWIW.
 
Fast Eddie said:
Float is different to bounce. Float is when the follower leaves the cam. Bounce is when the valve bounces after being slammed back into the valve seat too fast. FWIW.
Click to expand...

Good point. I'm off topic again with the witness mark and bounce stuff...

Would float leave a witness mark? Seems contradictory to me, but I am not a valve train engineer. Coil bind for sure would. Hard to believe I have coil bind given how I installed the springs, but who knows.

I watched JC's video of the PW3 cam with Sir Nigel's Honda valve springs. Any relation to you? Bounce is not seat and valve face friendly.
 
Yes, IIRC valve float leaves a mark across the nose of the cam caused by the follower hitting the cam when it lands.
 
Fast Eddie said:
Yes, IIRC valve float leaves a mark across the nose of the cam caused by the follower hitting the cam when it lands.
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That I don't see on any of the Norton cams I have... yet. More spring pressure should eliminate that possibility, no?
 
Schwany said:
That I don't see on any of the Norton cams I have... yet. More spring pressure should eliminate that possibility, no?
Click to expand...
Yes, more spring pressure would solve it. But too much spring pressure may cause coil bound or other issues!

Actually, I learned a lot from Comnoz’ spintron videos. I had always been a fan of keeping spring pressure to a minimum. In fact I used to set up a race engine with just enough pressure to cause valve float at a certain rpm, and then use that as a rev limiter !

But Comnoz’ spintron work made me realise that’s wrong, a certain pressure is needed to maintain valve train integrity and stop all sorts of unwanted moving / fretting / resonance / bounce / etc !
 
The line across the lifter is not caused by valve bounce - t is caused by spring pressure at peak lift from the point of the cam (the pointer the cam the more wear). See the spintron video below for details. I made this vid because there are a lot of misconceptions about valve bounce and lifter wear. The big danger of valve bounce is valve clash. The solution is appropriate cam lobe ramps - preferably assymetrical ramps that let the valve down more gradually. I used cheap oil in the vid so I could see some cam/lifter wear.

 
jseng1 said:
The line across the lifter is not caused by valve bounce - t is caused by spring pressure at peak lift from the point of the cam (the pointer the cam the more wear). See the spintron video below for details. I made this vid because there are a lot of misconceptions about valve bounce and lifter wear. The big danger of valve bounce is valve clash. The solution is appropriate cam lobe ramps - preferably assymetrical ramps that let the valve down more gradually. I used cheap oil in the vid so I could see some cam/lifter wear.

Click to expand...

I'm sending you a PM if you don't mind.
 
So far nobody has recommended what valve springs to use. I just want adequate spring pressure and coil bind clearance for the Web 312a cam.

I would also like a recommendation for valves.
 
Dan1950 said:
So far nobody has recommended what valve springs to use. I just want adequate spring pressure and coil bind clearance for the Web 312a cam.

I would also like a recommendation for valves.
Click to expand...
Have you asked the supplier of the cam for a valve spring recommendation ?

Both Jim Comstock and Jim Schmidt will supply you with a valve and spring kit.
 
Dan1950 said:
So far nobody has recommended what valve springs to use. I just want adequate spring pressure and coil bind clearance for the Web 312a cam.

I would also like a recommendation for valves.
Click to expand...
"Black Diamond" valves (inlet and exhaust). Regarding coil bind, there was instruction with the Service Release about coil binding on the 2S (Combat) cam that described how to lever the valve at max lift to assure that there's on coil binding. It's pretty much brute force but it's the really reliable test of your setup.
 
Blewdy Yaink said:
"Black Diamond" valves (inlet and exhaust). Regarding coil bind, there was instruction with the Service Release about coil binding on the 2S (Combat) cam that described how to lever the valve at max lift to assure that there's on coil binding. It's pretty much brute force but it's the really reliable test of your setup.
Click to expand...
I have purchased the (std size) Black Diamond valves, beehive springs and retainers.
 
Dan1950 said:
I have purchased the (std size) Black Diamond valves, beehive springs and retainers.
Click to expand...
IMO, good choice. Check out the Service Release for checking valve clearance for the 2S cam (mid-1972) in the INOA or NOC archives.
 
Schwany said:
If JC likes that webcam, it's probably a good one and will be what you are looking for.
Click to expand...
Unless he has changed things recently, Jim has gone back to a stock cam for his 924 ? cc road bike. He found that it gave the greatest midrange power. I imagine he is also expecting that it will last longer than his last bumpety cam did. The early demise of that one prompted the oil testing, iirc.
Just spent an hour reading old threads on camshaft problems/choices.
Most interesting.
I have a very boring life when it comes to camshaft stories. And that is a good thing!

Glen
 
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