Roller Camshaft

Crower had a cam with needle bearings many years ago. I remember the full page adds for it when I was a kid. Nothing ever came of it. According to some SAE papers, the friction contribution of the cam bearings is very low when compared to other parts like piston rings and main and rod bearings.

John Woodward

80% of the friction in the short block is in the oil ring. I've been building low to ultra low tensioned oil ring motors for years as a standard practice even on the street with out vacuume pumps. it is all in the Honing process and stone/brushes used that makes it work or become an oil consumer. The Big American auto makers are finally doing this.
As for needle bearing on cam journals, the cams themselves can be pretty expensive. I like to make myself feel better by saying that some people are so trick, they usually out trick themselves. I am a FREAK when it involves COST EFFECTIVE POWER. ROVERV8: What are you building that has you thinking about needle bearing cam journals?

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

I am building a couple of Rover V8's, for classic racing, to one X-bolted block I have fitted 4" sleeves to take chev rods and pistons. I intend using roller lifters if possible, and had been told the Nascars and Australian V8 touring cars were using the needle roller bearings to reduce friction.

I refuse to run anything but roller cam bearings with my race roller cams. I made the switch 7 ~ 8 years ago, when the more agressive profiles I began running resulted in a curious wear problem with the "flat" babbit bearings I had been running. The problem even sent us home 2 days into a 3 day event at Maple Grove Raceway Park when the cam froze while coming back down the return lane (good timing).

The problem wasn't caused by running, but during startup. Every time we bumped the engine over, it took a small toll on the bearings. Do it enough times and the bearings would give up.

The top NASCAR touring series use roller cam bearings and they do give some friction savings. But Shaun is right. A very light and low tension ring set will give a really big return. The top ring(s) seal because combustion gasses expand behind them, not because of high radial tension. High tension = high drag. Most ring makers will tell you the rated radial tension of their rings. Some will offer back cutting services or you can back cut yourself to further reduce radial tension and weight for that matter. DO NOT back cut and use an approriate alloy top ring if using Nitrous or supercharging.

Keep in mind, there are a couple of different roller bearing sets to choose from AND be sure that block will accommodate and support them. Also, have someone with past experience with that block (if at all possible) do the work.

Yes, use a roller cam and lifter set. The primary advantage will be the profile. Friction reduction will be a secondary gain.

The comment was made that there are a couple of different roller bearing sets to choose from, what's the difference??
Also are you using steel cams as I think the hardness of cast iron is not enough to run in the needle rollers.

You have to run an oil ring in a 4 stroke.
Honing it correctly (which virtually no one knows how,)
allows a low tension such as the TotalSeal Gold Power oil ring(Mfd by Hastings) to run without oil problems. You can literaly cut the drag in half when compared to some of the "STD" tension oil ring packages. Detroit quit using them so why would anybody use them? If you take a block to get honed and ask the man who will be honing the block what a Profilometer is, and he tells you he doesn't know, and when asked if he brushes the bore after he hones it, and he says no, go find some one else to hone it. You will get my point when you drag a dry cotton ball around the cylinder and see it snag.

The Cast cam core that you can use for a roller cam is called an Inderall core. It does not use a roller journal bearing, though.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

2 strokes don't have a sump full of oil, but it never hurts to relook at the current state of the art

Regards
pat

Amen!

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

Any body want to build a dyno thrasher 350 Chevy with a Gapless top ring/Tapered Cast second and leave the oil rings out of it to see if it blows oil in every direction?
I'd like to see if it worked reasonably even with a dry sump/vacuume set up.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

Roverv8, different diameters and widths are available. It is VERY important to make sure that block will accommodate. I was a teenager the last time I saw the Buick version of that block. I don't know if it had enough meat to support those bearings...I'm sure it has been improved with time.

Good point(s) Shaun. The cylinder walls should be prepped very "softly". They should look like they were honed with steel wool.

As for oil control. I run .005" under on 3mm low tension sets. No problem. Don't think I'll go without though. My next NA engine I am considering not running a second ring.

I have not looked at the Buick block recently. Don't know about the reliability concearning the needle bearing journals.

On production cast iron blocks the final .0015 of honing is finished via a JHU623 or JHU625 Both 280 Grits, but the 623 is a softer material that works better on harder surfaces. Once you finish it needs to be brushed for about 10-15 strokes. These final processes will deliver a considerably longer and better sealing surface, when using a moly top/cast second, than the common practice of final honing with an 820 stone(400 grit) and not brushing the bore afterward. SUNNEN and all the ring manufacturers back me up on this. One will also see an instant seat if he lacquer thinner's everything clean and then assembles the cylinder wall lightly oiled with 5W20(then wiped dry with paper towel, leaving only a microscopic oil film)

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

Shaun,
Just to clarify: even with this attention to detail, can you run the low tension rings on a street car for 100k+ miles? I think I know the answer based on your comments about the OEM's, but when I finally get around to rebuilding my engine I want to do it right and, as you mentioned, COST-EFFECTIVE! I'm not what you would call "well-oiled"! HA HA!

Okay that was bad. Sorry

I have not experienced any problems. Just avoid any excess piston to cyl clearance. After the motor has about an hour on it and a couple of pulls on the dyno or a couple of passes down the track, it is ready for full synthetic oil.
The hone lasts so much longer with synthetic oil. I recently looked at a couple of cylinders on one of my daily drivers with video through the spark plug boss in the head. I also do this regularly on every race engine I build or inspect. The cross hatch looks excellent and there is no noticable ridge. It's had MOBIL1 since I've owned it at less than 30K miles. It now has 318K, doesn't smoke, leak, or use any oil. I still run 5W30 in it, and it's a V8 truck that get's worked pretty hard regularly. The only thing I have replaced internally is the timing chain.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

RoverV8,

I missed the question earlier re. steel cam core. Yes, I run a special billet steel core. This is a different core than a standard solid roller core. Shaun's Co has direct sources for these cores.

They are 8620 Billets.

Shaun TiedeULTRADYNE Arl,TX(stiede@ev1.net)

Another advantage of roller camshaft bearings is the camshaft is better located. Meaning the cam is not "floating" on oil in the bearing. The entire valvetrain will be much stiffer, and a stiff valvetrain is a good valvetrain.