roller cam ?

[ßill]

A long time ago (early 60's) there was an article in "HOTROD" magazine about a "roller cam". This cam was supported by needle bearings and followed by roller lifters. I don't remember if this was topped off by roller rocker arms or not. This system significantly reduced the friction associated with the cam. Has this arrangement has been rejected in favor of roller lifters and rockers supported by conventional bearings? It seems to me that the major point of friction is still the cam bearings. Does any one remember this idea? Can anyone shed any light on the demise of this system?

 

[jfb4548]

Roller Rocks!

Roller cams are alive and well. There are both Hyd. and solid versions available. Solid is more a pure raceing set due to the extreem valve spring pressures required to keep the lifter in contact with the cam. Some pretty radical cam profile! The hyd. ver. are used in some new vette motors, and even the hi-po mustangs. Most likely others too. These use a milder cam profile and spring pressures about that of a mechanical cam.
Race cam grinds require roller rockers do to the hi lift and big valve spring pressures...600+LBS when valves are opened.

Hyd. cams would work with a hi lift stock type rocker arm, a roller tip or full roller rocker. Just make sure the slot in the arm is long enough to allow for the increased cam lift.

Rollers rockers come in two types: 'roller tip' only rockers or the full race type with 'rollers' both in tip and fulcrum. The full roller rockers are much bigger and will not fit stock valve covers.

Both use standard bearings in the block. Ive never seen roller bearings in a standard chevy block. Maybe some of the new motors? Not up on the latest toys!

 

[ßill]

Thanks for the reply John. The bearings in the block are the ones between the block and the cam. If I remember the article. the torque needed to turn the assembled engine w/o spark plugs to about 1/10 with the needle bearings. The only negative I can see was possibly maintaining oil pressure and I am sure that can be overcome. Any thoughts?

 

[MaineShark]

I do remember reading something about roller cam bearings a while back. If I recall correctly, the block needed to be modified, since the bearings had a much larger outer diameter than standard cam bearings, and the gains were only really significant at high revs when friction becomes a major factor. I doubt it would be cost-effective for a regular engine. I think it was more of a thing for dedicated race engines that were going to be turning up crazy revs.

Joe

 

[warren s]

Back in the 60s some work was done using somthing called Torrington needle bearings. The cam journels were much larger to support a separate bearing.

The expense was not worth the minimal power increase.

This was also attempted with the crankshaft but torsional instability proved destructive to the bearing.

 

[JohnZ]

Porsche used roller bearing cranks in their 550 Spyder race engines and in the 1600 Super production models in the late 50's and very early 60's; they had roller bearings for the mains and for the rods, which required a 6-piece built-up crank with machined Hirth joints and bolts at each bearing location. They worked fine in race engines, but low-rpm street operation ("lugging") destroyed them, as it brinelled the bearings. They were incredibly expensive, and the feature was only offered for two years on production cars due to failures.

 

[motorman]

NASCAR engines use roller bearing journal camshafts. the camshaft also must have hardened journals like roller lifter camshafts. the main reason for the roller camshaft bearings is the heavy tension valve springs used to get the engines to turn 9500 RPM would destroy plane camshaft journal bearings.