Stripped cam gear

[Dick Weiss]

Grooving the cam gear to relieve a little aquaplaning--like the groove(s) in tires, altho not having additional grooves w/sipes connecting it/them, the oil has nowhere to go. Straight-cut gears allow the oil to exit on both sides of the gears vs the angular gear teeth.

Years ago, during a teardown of a 'C' engine (which had a lotta noise in the 3rd piece) which @ idle, it sounded like a diesel during a WCH in Colorado--we did get it (not my car) back home, and found that
the 3-bolts and locking tabs were loose! Luckily, as long as we kept the revs up, the engine ran kinda OK.
There were no broken teeth like this photo shows.

[Martin Benade]

Wouldn’t oil leak out of the edges of the gears regardless of being straight or angled? I would expect no difference.

[David Jones]

Tried the grooved cam gear on a Vee engine 30 plus years ago. No discernible hp difference but how can you tell with an analog Stuska water brake. Hard to tell 1 ft/lb of torque let alone a needles width of difference on some of the things we tried.

[Martin Benade]

Did it strip it’s teeth?

[Wil Mittelbach]

Any ideas on what may cause this failure?
Engine is modified with dual valve springs.

Don't understand why you have dual valve springs which increase the load/scuff on camshaft lobes, per the camshaft/crankshaft gear loads of hi-rpm race cars with more frequent engine overhauls than those of normal 356 street engines. Or, perhaps you're targeting for 6k+ rpm performance with a radical cam?

[Harlan Halsey]

That grooved cam gear idea was tried and rejected prior to 1975! Supposedly it was to reduce the cam gears "pumping" oil, but it had no measurable HP benefit and as Vic noted above, doing so seriously weakened the gear.

[Vic Skirmants]

That grooved cam gear idea was tried and rejected prior to 1975! Supposedly it was to reduce the cam gears "pumping" oil, but it had no measurable HP benefit and as Vic noted above, doing so seriously weakened the gear.

Helical gears don't "pump" oil like the straight gears in our oil pumps. Saw a gear once that had TWO grooves.

[jule block]

Mark,
Where in Minnesota are you? I am in chaska. Would like to see what you find.
Jule

[Mark Schumacher]

Jule
I am in South Minneapolis
Send me a email or a PM
Engine is now on stand, will be a bit before I get back to it
Mark

[Ron LaDow]

Helical gears don't "pump" oil like the straight gears in our oil pumps. Saw a gear once that had TWO grooves.

I've wondered if the sound of straight-cut cam gears is more from the instant mechanical contact or the pumped oil...
Regardless, a helical gear set is going to move the oil from one end to the other without trapping much at all.

[Al Zim]

The gear that fits on the camshaft comes in a variety of sizes. With the use of a dial indicator you can check the backlash of the cam and gear and this situation will be eliminated. If in doubt you should use some prussan blue to check the pattern of the gears. This method of driving the camshaft was developed in the mid 1930's. Millions of 25 and 36 engines were built and 10 million plus of post 1961 engines.

[Mark Schumacher]

I have stripped the engine down further
- cam gear removed
- heads removed. They are fine, no seized valves
- lifters move as they should. Smooth, full travel
- cam rotates easy and smooth and then hit something with a hard stop. Clunk. Dowel pins not hitting.
Any ideas?

[Martin Benade]

That is with the stripped gear removed?

[Mark Schumacher]

Yes
Can rotate cam by hand with smooth operation until the clunk

[Mike Wilson]

Broken cam gear tooth in there somewhere?

Mike