Anyone tested regular cam bearings to roller cam bearings?

[5.0stang]

I was just curious if there was any HP to be gained?

Is it better to run on a thin layer of oil film (regular) or spin the bearings (roller)?

Thanks.

[black_z]

I'm sure rollers are better if the cup guys use them.

[MadBill]

Ah, but do they still? I've heard stories...

[Windsor377]

The OHV engines I've had a part in that are in 9.5 - 10k + rpm range use babbit cam bearings.

Those in the 8 - 9k+ range, and have less servicing, use roller.

As for hp differnces, no I can't supply that answer. The engines with the babbit bearings will not physically fit teh roller bearing for comparison. The engines running the rollers, I just wont put a babbit bearing in them, because of the maintenace cycles they have.

It is my thought, those extended maintenance cycles lead to a babbit cam bearing failure once. Right or wrong, I switched and never looked back and never had another cam bearing failure.

[want-a-be]

A Pro Stock team I had access to before they retired from racing did a test on this. What they found was that there was no real added hp with the roller bearings.

But they did find that by going to the same size cam bearings all the way through could free up a few hp. What they did was line hone the cam journal. Once they got everything in line they could put the cam in and the weight of the dowel on the cam was enough to turn the cam. Thats how easy it turned.

Their thinking after that was ...roller bearings were more for endurance racing.

Later, Don

[MadBill]

I have seen in an older thread here that one issue with babbit bearings is a tendency to scuff with 1,000 lb.+ springs during cranking, before the hydrodynamic wedge can develop...

[Unkl Ian]

Was it Smokey,that built a roller motor,and found no power gains ?

Pretty sure he mentioned that in his book.

[CNC BLOCKS]

I have two 8-71 blower SBC engines with 1250 over the nose and and BBC babbit cam bearings and we have to whirl them quite a bit on the blower starter to get them fired and we have never scuffed and cam bearings in 13 years.

[CamKing]

I have always looked at Roller bearings as a reliability upgrade.
I've never seen any power gains.

The most interesting thing I've seen was on the Buick V6 Turbo Indy engines.
The cams ran small bearings, and had a small barrel diameter(.900").
After they'd run a few hundred miles, you could look at where the roller lifter was tracking on the cam lobe. You would see that one edge of the roller follower would be tracking more then the opposite side.
at first I thought that either the lobes had been ground with a small amount of taper, or that the lifter bores were not 90 degrees to the cam centerline. We checked, but couldn't find anything wrong.
A few years into the project, they switched to roller bearings. The journals for the roller bearing cams were only .006" larger diameter then the old cams, and the barrel size was the same. With the roller bearings, the tracking on the lobes became much less noticable, and was even across the face of the lobe. You no longer had one side of the lifter roller digging into the cam.
The only conclusion I could come up with was with the older style cams were flexing, and that by switching to the roller bearings, thier lack of bearingto journal clearence was making the cam more ridged.

[n2omike]

There are some guys here running 460 BB Fords that have problems with scuffing standard cam bearings, as the bearings are fairly narrow. One fix, is to use wider bearings. Another is to go roller.

There was somebody on the http://460ford.com forum selling sets of the wider bearings at one time. (I believe they were one of the 351C bearings.)

Anyway, it's a popular fix for BBF's running big rollers and big spring pressures.

Good Luck!

[black_z]

Ah, but do they still? I've heard stories...

Well, if you've heard stories! Maybe not anymore.

[Adger Smith]

A long time ago one of my "Cup Buddies" told me the only reason they used the roller bearings was they helped accelerate off the corner a little quicker. No HP gain on the dyno, but they could control oil/windage better.

[compguy]

and would another benefit of babbit vs roller be that a given cam core id, for instance on say a SB chev take a 55mm roller cam bearing, but a 60mm babbit bearing, so the benefit is a larger cam core = stiffer cam with all of the benefits of same?