Cam Grinding

[bruce]

My machine has built-in capabilities to taper grind a surface. The machine I purchased is also being used in 2 other cam shops that I know of to grind small engine cams but unfortunately they are not willing to share any photos with me on how their's are setup. One is used for Harley cams and the other for 4 cycle snowmobile engines.

[106-1194218389]

Bruce, did you mention how or where you were going to get your masters? Were you going to have the ability to copy cams? I know my friend had all sorts of criteria, diameter of lifter base, rocker arm ratio etc. On your flathead it would be direct push off the lobe so the lobe itself "looks" smaller that say a small block chevy of same duration etc. The cam you showed us in the picture must have been pretty healthy then.

[bruce]

My masters will be machined using a rotary table on my milling machine, actually have machined one master already to play with. Maybe someday I'd look for someone with CNC to generate masters from my CAD layouts. But keeping them "in-house" keeps my costs down and this is a down and dirty way to get my cams I'm hoping.

The cam I showed was an old cast weld/regrind from someone else, it was around 230-240 duration most cam profiles now in my class are running +280 duration and .340 lift. I would be able to copy a cam but do not plan on doing that as I want to develop something myself and not copy someone else's profile.

But it does take a lot of R&D . . . I really don't have a plan or idea what I'm doing . . . but then again at one time I had no idea what a flowbench was either nor had a dyno to work with and now I have both of them in my shop

[Tony]

Keep doing the R&D Bruce.

Jfholm is right about grinding a taper into the lobes. This is usually done by dressing the wheel at a very slight angle before the final cut. The grinding wheel ends up being a very shallow cone shape not perfectly cylindrical. The cam lobe then contacts the cam follower off center and causes the follower to rotate in its bore. The amount of lobe taper determines how fast the cam follower rotates in its bore. Either zero rotation, or too fast rotation will quickly wear things out, so some experimentation and compromise is required. The only lobes ever ground dead square are lobes intended for roller followers.

As long as there is plenty of oil, and the followers rotate fairly slowly in their bores, the lobe and follower should live happily together.

[106-1194218389]

Hey Bruce that's what you need to do - develope a roller cam for your flathead!

[bruce]

[106-1194218389]

Put massive spring pressures in you thought process then. I know on our drag cars we are at 400 pounds on the seat now and about 900 pounds open

[Tony]

But side valve engines have beautiful direct valve actuation, really the same as a direct acting overhead cam engines.

In fact, you could probably do a whole lot worse than shamelessly copying cam profiles off some Japanese DOHC engines. They have obviously figured out suitable valve motions for direct acting bucket on valve operation, which should work just as well with side valves, hehehe.

Perhaps all you need for getting some suitable master cam profiles is a hacksaw. If the rotation is opposite, just flip the lobe around and mount it from the other end.

These 4 valve DOHC engines always have cam bearings located very close to the lobes, so all you would need to hold a single master lobe in your machine would be a big collet chuck to grab the original cam bearing surface. You might be able to do something really clever with a large commercial taper lock fitting, to make a big bore custom collet chuck to fit a reasonable range of cam bearing sizes.

Aftermarket Japanese cams often appear on e-bay so you would not be limited to just the standard original factory durations.

[bruce]

[Tony]

[bruce]