About time for the spintron

jseng1 · Jul 29, 2015

With so much damage potential it seems like you would want to design a cam with the closing ramp you found with the profiled lifters but configured for lightweight radiused lifters. That would give you less valve float. Splicing the profiled closing ramp data onto your favorite cam wouldn't be too hard and you already have the data. The $600 or so required to get Web cam to make a new master made for BSA lifters is expensive but not a bad idea if you are going to have catastrophic failure with the stock heavy lifters. I know its doable because I've done something similar with Megacycle. Note that new BSA lifters are now available from SRM.

comnoz · Jul 29, 2015

jseng1 said:
With so much damage potential it seems like you would want to design a cam with the closing ramp you found with the profiled lifters but configured for lightweight radiused lifters. That would give you less valve float. Splicing the profiled closing ramp data onto your favorite cam wouldn't be too hard and you already have the data. The $600 or so required to get Web cam to make a new master made for BSA lifters is expensive but not a bad idea if you are going to have catastrophic failure with the stock heavy lifters. I know its doable because I've done something similar with Megacycle - putting smoother ramps on the PW3/JS2 type cam. Note that new BSA lifters are now available from SRM.

Whether the profile is done on the lifter or the cam will not make a difference. It the valve floats severely -damage is likely.

There is more to it than splicing on a closing ramp. Otherwise I would just make up a master on my CNC and send it to Webcam.

This was the 3rd lifter that I have broken the Stelite on since I started the spintron testing. Two Norton lifters and one BSA lifter. On the other two lifters, most of the Stelite remained attached to the lifter body. This time the Stelite shattered into a thousand pieces. Jim

Hobot · Jul 29, 2015

No metallurgy exotica alloys allowed Norton rotary crank to survive for production till they froze it. NASA then NASCAR too. Got to crack more eggs to make this cake spin. Thank you Sir Eddie for leading us into these new heights and lows of Norton life.

Dances with Shrapnel · Jul 29, 2015

Jim,

In all the years and races that Herb maintained and campaigned my 500 USS Norton we never lost a stellite and I think we lost one stellite on the 750 USS. The 500 USS uses the Dunstall style lifters whereas the 750 USS uses the BSA type.

Do you have a hunch (or solid idea) as to why you are loosing them here? Is it the abuse, the specific material, method of attachment or maybe the stock lifters are not stiff enough? As far fetched as it might seem, is there any chance that the oil is not warm enough (too viscous) to get where it needs to be?

Thanks for all you have been putting forth and sharing. Great stuff!

comnoz · Jul 29, 2015

Dances with Shrapnel said:
Jim,

In all the years and races that Herb maintained and campaigned my 500 USS Norton we never lost a stellite and I think we lost one stellite on the 750 USS. The 500 USS uses the Dunstall style lifters whereas the 750 USS uses the BSA type.

Do you have a hunch (or solid idea) as to why you are loosing them here? Is it the abuse, the specific material, method of attachment or maybe the stock lifters are not stiff enough? As far fetched as it might seem, is there any chance that the oil is not warm enough (too viscous) to get where it needs to be?

Thanks for all you have been putting forth and sharing. Great stuff!

The Stelite has not simply broken loose as happens occasionally. They are cracked in many places. They crack because they get hammered by the cam when there is separation of the valve train parts.
There is no missing the sound the spintron makes when the valve train gets to the point of separation. Like a high speed jackhammer. You need ear protection. Jim

Dances with Shrapnel · Jul 29, 2015

I will have to qualify and say I did not see the stellite we lost, only a verbal report from Herb Becker. I don't know if it crumbled as you show and describe or if it "came detached". It was likely either Tim Joyce or Rob McClendon who was racing it at the time.

The point is you describe what has happened (what you see and hear) and I am trying to gain some insight into why it is happening. Most all of your spintrons show valve bounce at the seat but we don't know if the valve is lofting off the nose or not. Do you suppose the damage to the stellite is while the valve is bouncing on the seat - but how can that be when there should be valve lash and perhaps an adequate hydrodynamic wedge of lubricant.

Furthermore, my 750 USS ran a N480 with periodic excursions to 9,000 rpm and regular excursions to 8,000 rpm with only one failure. The 500 USS even lived with a rev limiter set to 9,500 rpm and we used every bit of that with no loss of stellite.

Both engines used lighter (probably stiffer) cam followers and lighter and enhanced valve train components though with the 500 we resorted to a gear driven valve train and purpose built cam (with center bearing of Herb Becker's design) designed by Professor Gordon Blair.

What I am saying is that with all we did, I would consider myself very lucky if either of my valve trains did not hammer yet we only lost one stellite. I am looking at the differences between your and my valve train components and applications here and trying to make some sense out of it.

I am just trying to get my head around the whole thing and the stellite loss is just one bit of the whole thing.

Thanks again for all your effort

comnoz · Jul 29, 2015

Dances with Shrapnel said:
I will have to qualify and say I did not see the stellite we lost, only a verbal report from Herb Becker. I don't know if it crumbled as you show and describe or if it "came detached". It was likely either Tim Joyce or Rob McClendon who was racing it at the time.

The point is you describe what has happened (what you see and hear) and I am trying to gain some insight into why it is happening. Most all of your spintrons show valve bounce at the seat but we don't know if the valve is lofting off the nose or not. Do you suppose the damage to the stellite is while the valve is bouncing on the seat - but how can that be when there should be valve lash and perhaps an adequate hydrodynamic wedge of lubricant.

Furthermore, my 750 USS ran a N480 with periodic excursions to 9,000 rpm and regular excursions to 8,000 rpm with only one failure. The 500 USS even lived with a rev limiter set to 9,500 rpm and we used every bit of that with no loss of stellite.

Both engines used lighter (probably stiffer) cam followers and lighter and enhanced valve train components though with the 500 we resorted to a gear driven valve train and purpose built cam (with center bearing of Herb Becker's design) designed by Professor Gordon Blair.

What I am saying is that with all we did, I would consider myself very lucky if either of my valve trains did not hammer yet we only lost one stellite. I am looking at the differences between your and my valve train components and applications here and trying to make some sense out of it.

I am just trying to get my head around the whole thing and the stellite loss is just one bit of the whole thing.

Thanks again for all your effort

You likely had a valvetrain and springs that were controlling things well enough to prevent broken Stelite -most of the time.

With the IRL springs I am not experiencing valve train separation and it runs quietly to 10,500 with only a small amount of valve loft visible on the laser sensor. The lifter is back to the cam before the end of the acceleration ramp so it is causing no problem.

I think the likelihood of a broken Stelite is small with either lifter as long as the valve train is under control.

Of course, if I had lots of time, I would like to develop a cam to run with BSA lifters that could run to 10,500. With high RPM there is obviously a small advantage to be had by using lighter weight lifters. None of the cams presently made for BSA lifters are capable of that kind of RPM. With the time available the best I can do is profiled lifters on an available grind. Jim

Dances with Shrapnel · Jul 29, 2015

comnoz said:
You likely had a valvetrain and springs that were controlling things well enough to prevent broken Stelite -most of the time.

With the IRL springs I am not experiencing valve train separation and it runs quietly to 10,500 with only a small amount of valve loft visible on the laser sensor. The lifter is back to the cam before the end of the acceleration ramp so it is causing no problem.

I think the likelihood of a broken Stelite is small with either lifter as long as the valve train is under control.

Of course, if I had lots of time, I would like to develop a cam to run with BSA lifters that could run to 10,500. With high RPM there is obviously a small advantage to be had by using lighter weight lifters. None of the cams presently made for BSA lifters are capable of that kind of RPM. With the time available the best I can do is profiled lifters on an available grind. Jim

Fair enough.

I seem to recall we were running R&D race springs in the 750 USS and Herb resorted to some special springs for the 500 USS; maybe we got it right. I understand time constraints but rather than developing a new cam, take a look at the cam and valve train in my 500 USS; you have all the bits. It would be interesting to see how well it behaves in the spintron.

Thanks again.

comnoz · Jul 29, 2015

Dances with Shrapnel said:
comnoz said:

You likely had a valvetrain and springs that were controlling things well enough to prevent broken Stelite -most of the time.

With the IRL springs I am not experiencing valve train separation and it runs quietly to 10,500 with only a small amount of valve loft visible on the laser sensor. The lifter is back to the cam before the end of the acceleration ramp so it is causing no problem.

I think the likelihood of a broken Stelite is small with either lifter as long as the valve train is under control.

Of course, if I had lots of time, I would like to develop a cam to run with BSA lifters that could run to 10,500. With high RPM there is obviously a small advantage to be had by using lighter weight lifters. None of the cams presently made for BSA lifters are capable of that kind of RPM. With the time available the best I can do is profiled lifters on an available grind. Jim

Click to expand...

Fair enough.

I seem to recall we were running R&D race springs in the 750 USS and Herb resorted to some special springs for the 500 USS; maybe we got it right. I understand time constraints but rather than developing a new cam, take a look at the cam and valve train in my 500 USS; you have all the bits. It would be interesting to see how well it behaves in the spintron.

Thanks again.

I have run an N480 with BSA lifters on the spintron. I could get control up to 8500 with the IRL springs. At 9000 rpm I had a lot of seat bounce but very little loft. No broken Stelite.

I did have a few broken valves when using one in my racebike some years ago.

Dances with Shrapnel · Jul 29, 2015

Thanks again Jim.

Good to know you have benchmarked the N480. Now to get it to 10,500 rpm

About time for the spintron

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