About time for the spintron

comnoz · Apr 27, 2015

jseng1 said:
Thanks for the better vid of whats happening at the rocker arm tip.

Webcam says that the 86C cam is a combat cam. Is this right?

The 86C/12C is a combat cam.

The 86C is similar to a PW3. Jim

comnoz · Apr 27, 2015

Here is what I am doing to help with cam flex in the new "billet" motor I am building.

CanukNortonNut · Apr 27, 2015

Jim
If I am not mistaken, you are only using one side of the cam when things are spun up with the spintron? Would not the other lifter pushrod spring/s etc. influence the dynamics of the bounce issues? Would the overlap of the cam design on the other cylinder change how the testing influences the valve behavior?
Cheers,
Thomas
CNN

comnoz · Apr 27, 2015

CanukNortonNut said:
Jim
If I am not mistaken, you are only using one side of the cam when things are spun up with the spintron? Would not the other lifter pushrod spring/s etc. influence the dynamics of the bounce issues? Would the overlap of the cam design on the other cylinder change how the testing influences the valve behavior?
Cheers,
Thomas
CNN

That is a possibility that I will be looking at.

I have seen that the cam deflection from the exhaust lobe is quite a bit less because it is nearer the end of the cam so how much the next lobe -which would be the exhaust lobe on the other end of the cam will affect the intake I am watching is questionable. Time will tell. Jim

Snotzo · Apr 28, 2015

I have just realised I am not in sequence with the spintron because I am taking data from the left cylinder components whereas the spintron is running on the right cylinder. This being the case my calculations will not be indicating the camshaft deflection that will be present on the right because the left cam lobes are well positionad next to the bearing, and the right cylinder cam lobes are somewhere near the middle of the shaft, and thus lacking the same support.
I cannot correct this at present simply because I do not have a camshaft with me, but hope to have the data for the right side in a day or so, then I will re calculate.
My apologies for any mis representations my earlier post contained as a result of this oversight.

billet · Apr 28, 2015

comnoz said:
Here is what I am doing to help with cam flex in the new "billet" motor I am building.

Was just about suggesting a similar solution before your post!

I have had thougts abot doing it myself for a while, making it easier to change camshaft as well.

I borrowed a Mick Hemming PW 3 camshaft, measured the liftcurve and got help to make a master for BSA lifter, believing the PW 3 was easy on the valvetrain.
Obviously i should try to make the closing ramp and nose a´bit more gentle like the 86c and Axtell 3 cam.

I relly enjoy this thread, very educational and full of surprices.

Sten

Snotzo · Apr 28, 2015

My previous post re the Comnoz spintron measuring the right hand cylinder is incorrect. Jim is taking all measurements and filming the events taking place in the left hand cylinder.
I therefore have to do an about turn and go back to my original computer runs, and now that a friend had supplied me with some data I was lacking for the camshaft, I will start again from scratch. I regret any confusion this might have caused, and can blame no one but myself for assuming something instead of checking to make sure.

comnoz · Apr 29, 2015

A couple more tests this evening. I got some new conical springs to compare and I like the results. They are pretty similar to the conicals I have been using but they are made by a different company. They have a lower spring rate and are made using oviate wire instead of round wire. This lets me increase the seat pressure and at the same time decrease the open pressure. I was hoping this would decrease the amount of cam deflection and help the bounce. I am quite happy with the result.

Here is how the test is run.

[video]https://youtu.be/l0oguA2o4mw[/video]

And here is the slow motion video -first with heavy steel pushrods [ 20 grams more than stock] then with stock aluminum pushrods. Both tests were run at 8500 rpm since that is where I had been seeing a lot of bounce with the 86C cam. By the way the results at 7500 rpm showed no bounce and nearly perfect valve control.

[video]https://youtu.be/qE5Z8vAkGNc[/video]

I wish I could show you the trace from the laser and cam sensors but as of yet I don't have a way to get them to a PC. Jim

Hobot · Apr 29, 2015

very cool comnoz - feels a bit like watching Star Trek inventor of first wrap drive. About what stroke could take advantage of this potiental 9000 rpm valve train? Looking close seems the spring rebound waves is matching the slight valve bounce still seen.

[video]https://www.youtube.com/watch?v=DYE3nm9voUk[/video]

comnoz · Apr 29, 2015

hobot said:
very cool comnoz - feels a bit like watching Star Trek inventor of first wrap drive. About what stroke could take advantage of this potiental 9000 rpm valve train? Looking close seems the spring rebound waves is matching the slight valve bounce still seen.

The new 750 motor that is waiting for the last couple parts is 69mm stroke.

Hobot · Apr 29, 2015

69 mm eh, then a few more 1000 rpm of valve train control yet to attain to get top gear short stroke benefit.
For road race long strokes being able to stay in lower gears higher rpm sure pays off even if top speed tops out closer to lower torque peak rpm. Keep it up Jim as I just want to be a consumer.

comnoz · Apr 30, 2015

Here is as good as it gets for a longstroke motor with an 86C cam or less. 7500 rpm, stock lifters and pushrods, my new springs.
Notice how much less stem flex there is in comparison to the springs I have been trying.

[video]https://youtu.be/v1GEi3bqe8A[/video]

Here is a screenshot of the laser trace at 7500 rpm. The ripples at the base circle are from noise caused by using a soundcard as an A/D converter .

slimslowslider · Apr 30, 2015

Bravo!

comnoz · May 2, 2015

Since I like the lift of the 86C cam I want to run it in my new billet stroker motor. I need to reduce the effective duration a bit as I want the power to peak low enough to be usefull in a 91mm stroke engine.
So I cut a stock lifter with a 4 inch radius.
Here it is with a coat of black ink so I can measure the contact patch after it's run.

Now for a run to check the valve action. The 4 inch radius allowed around 1000 more rpm before loss of control set in.

[video]https://youtu.be/s4ZK3KW3ogQ[/video]

Since I plan on using a BSA follower in my new motor I needed to see if the contact patch will fit on a BSA lifter.
Here you can see it will not make it. I will need to reduce the radius to 3-1/2 or maybe 3 inches before it will be compatible with the short BSA lifter -or find a longer lifter.

comnoz · May 2, 2015

The next step. A couple BSA lifters ground to a 2.5 inch radius. A 3 inch might have worked but better safe than sorry. I can always increase the radius if there is room.

Now to check the oiling system.

A couple stock pushrods with the ball end removed and a cup installed.

I did a few tests with the high speed camera to check the valve control. With the 2.5 inch radius lifter I can run to 8800 rpm before things begin to go bad.

I pulled the barrel for a quick lifter check and noted I had created a couple lines through the center of the lifter by revving it till valve float.

Then back together for a 20 minute run to check the wear pattern on the lifter and cam.
I put a thermocouple in one of the timing chest bolt holes just to see how much temp rise there is with just two valves an oil pump and the spinning of the oil in the chest -with no hot oil from the head.

[video]https://youtu.be/Er2dr3d4FvI[/video]

Snotzo · May 4, 2015

There are items to consider when changing follower from a flat base to one with a radius.
The flat base standard Norton follower has a base length of approx 1.17". This base will accommodate the WC86C profile with room to spare.
Because the base is flat, the follower position is not that critical regarding it's centreline in relation to the centre of the cam. However, when a change is made to a radius follower of the BSA type, then the centreline position of the follower can become critical.

For safe actuation, the cam profile should at no point overlap the edge of the follower. With the 0.625" BSA follower length, this is drastically shorter than the standard flat, and because there can be a positional issue regarding it's centre line, the contact path of the cam on follower may well be off centre to the extent that one or the other of the cam flanks foul the edge of the follower.

The 1.125" radius BSA follower will accomodate the WC86C profile easily with room to spare, even if the follower in not exactly positioned on the centreline of the cam. Changing the radius to 1.5" and it is still just able to do the job, but the positional issue is now critical. For the WC86C intake profile, the 1.5" radius follower would be at the absolute limit..

With the WC86C intake profile, radii greater than 1.5" cannot be accommodated with a follower length of 0.625" because follower edge fouling occurs.

Regarding the compromise in area under the lift curve that results from changing from a flat follower to the 1.5" radius, the loss is in the region of 9.9%, although by way of compensation the surface stress with the radius follower is some 8.6% less.

The change to a radius follower does have the desired effect of easing the situation that exists with control of separation and bounce at high engine speeds. The smaller the radius is made, the greater the reduction in the opening and closing acelleration rates of the valve.

I must stress here, that the above is the result of calculations based on measured items that have been in my posession for that specific purpose. The WC86C cam profile data was forwarded to me in the form of an S96 file. The total may or may not be exactly representative of that which is running on the spintron, but is presented here as an example of the several issues that can arise when switching to a radius follower.

comnoz · May 4, 2015

Snotzo said:
There are items to consider when changing follower from a flat base to one with a radius.
The flat base standard Norton follower has a base length of approx 1.17". This base will accommodate the WC86C profile with room to spare.
Because the base is flat, the follower position is not that critical regarding it's centreline in relation to the centre of the cam. However, when a change is made to a radius follower of the BSA type, then the centreline position of the follower can become critical.

For safe actuation, the cam profile should at no point overlap the edge of the follower. With the 0.625" BSA follower length, this is drastically shorter than the standard flat, and because there can be a positional issue regarding it's centre line, the contact path of the cam on follower may well be off centre to the extent that one or the other of the cam flanks foul the edge of the follower.

The 1.125" radius BSA follower will accomodate the WC86C profile easily with room to spare, even if the follower in not exactly positioned on the centreline of the cam. Changing the radius to 1.5" and it is still just able to do the job, but the positional issue is now critical. For the WC86C intake profile, the 1.5" radius follower would be at the absolute limit..

With the WC86C intake profile, radii greater than 1.5" cannot be accommodated with a follower length of 0.625" because follower edge fouling occurs.

So what your saying is even though the contact pattern looks pretty good at 2.5 inches -I should reduce the radius more.
I will either do that or use a different lifter. Jim
Regarding the compromise in area under the lift curve that results from changing from a flat follower to the 1.5" radius, the loss is in the region of 9.9%, although by way of compensation the surface stress with the radius follower is some 8.6% less.

The change to a radius follower does have the desired effect of easing the situation that exists with control of separation and bounce at high engine speeds. The smaller the radius is made, the greater the reduction in the opening and closing acelleration rates of the valve.

I must stress here, that the above is the result of calculations based on measured items that have been in my posession for that specific purpose. The WC86C cam profile data was forwarded to me in the form of an S96 file. The total may or may not be exactly representative of that which is running on the spintron, but is presented here as an example of the several issues that can arise when switching to a radius follower.

Snotzo · May 4, 2015

So what your saying is even though the contact pattern looks pretty good at 2.5 inches -I should reduce the radius more.
I will either do that or use a different lifter. Jim

Because I cannot be absolutely certain that my calculations are based on the same set of components that you are using, I suggest you should check the followers to ascertain you have an unmarked witness line across both front edge and rear edge of your follower. If you see clearly such an unmarked line, even though it be only perhaps 0.010" wide, you are not fouling the lifter edge.

A follower with a roller instead of a radius pad would solve all issues of the contact kind, but would so drastically reduce the area under the lift curve that a new valve lift design would be needed to restore the situation. Such an alternative method is used in the Weslake engine, which has the BSA follower as the normal fitment.

comnoz · May 4, 2015

Snotzo said:
So what your saying is even though the contact pattern looks pretty good at 2.5 inches -I should reduce the radius more.
I will either do that or use a different lifter. Jim

Because I cannot be absolutely certain that my calculations are based on the same set of components that you are using, I suggest you should check the followers to ascertain you have an unmarked witness line across both front edge and rear edge of your follower. If you see clearly such an unmarked line, even though it be only perhaps 0.010" wide, you are not fouling the lifter edge.

A follower with a roller instead of a radius pad would solve all issues of the contact kind, but would so drastically reduce the area under the lift curve that a new valve lift design would be needed to restore the situation. Such an alternative method is used in the Weslake engine, which has the BSA follower as the normal fitment.

What would be your thoughts on reducing the radius only near the edge of the BSA lifter. I can offset my grinder and get a pretty clean transition from one radius to the next.

I have looked into a roller follower and even have built a prototype. The cost of a suitable custom billet cam put me off however. Jim

Brooking 850 · May 4, 2015

Hi Jim, home now so can view your videos, excellent info.
Have been discussing your testing with my engine builder, as he will be helping me with the next motor,he had done similar tests with V8 Chev motors in the past, he asked if you may get quite some different results running a piston and rings building cylinder pressure/compression against the inlet Vv and with/with out an exhaust system that caused some back pressure enough to slow the bounce on the exhaust valve
Any merits in this with your spintron and Norton motor? Just food for thought
Regards Mike