Roller cam bearings
 

Are there any real advantages to using a roller vs. a Babbitt bearing? I’ve never had any personal experience using them.

Re: Roller cam bearings
 

depends on the application--

Re: Roller cam bearings
 

Really interesting question. A person's intuitive reaction would be "of course, look at things like roller lifters and rockers", but I'll bet there aren't many engine builders who have actually done an A-B-A comparison of cam bearings.

Re: Roller cam bearings
 

Babbitt is the only way to go.

Roller bearings, when turning the camshaft on the engine stand, the camshaft feels drag free and it turns easily. However, during engine operation and load, there is more drag while turning. When using high spring pressures, the loading may cause the needle bearings to fail.

Re: Roller cam bearings
 

The biggest advantage of roller bearings are that they do not need pressurized oiling. So in most V8's you are blocking off 5 oil leaks inside an engine.

Re: Roller cam bearings
 

YES

Re: Roller cam bearings
 

So the advantage would relate to less oil coming from the cam journals, reducing windage in the crankcase?

Re: Roller cam bearings
 

My engine guy told me that Jesel experimented with roller cam bearings and the negative harmonics were real bad. That was quite a few years ago, maybe someone found a way to correct?

Re: Roller cam bearings
 

The roller bearings still need some pressurized oiling; they do not oil by themselves and although there are claims oil splash is enough, I have seen enough damaged roller bearings due to lack of oiling especially on endurance engines.
If you have the right cam journal an lifter bore clearance, you will not have to worry.
Yes, they are known to create harmonics issues and it shows in Spintron testing.

Re: Roller cam bearings
 

Not Legal in Stock ,,, correct ?

Re: Roller cam bearings
 

Jim I was thinking the same thing. Barry

Re: Roller cam bearings
 

What you may consider is isolating the camshaft by forming a closed tunnel with oil return run directly down to the pan. Cam, lifters and bearings see plenty of oil maybe too much but would not fall into windage with an internal or external oil return line or limit the fall to the rear only for not 100% effect.

When looking at this a few years ago it's difficult with SBC without a lot of work I spent hours cutting and filing PVC tube to fit planning to pin and epoxy but issues with connecting rod clearance made it too much work at that time and became evident sheet metal would have been a better choice.

When searching cases where I could see this actually done this was with a Ford with dry sump much easier to control putting oil in the front and return in the back the tunnel would be filled or nearly.
Great idea to apply to a stocker there would be HP there but the labor cost would be more than most would pay but a crafty guy doing it for himself............

Re: Roller cam bearings
 

A very good friend of mine that knows a few things about engine building and find HP told me that when the engine is running, the camshaft is spinning on a film of oil. It isn't dragging against the bearing material.
Dan

Re: Roller cam bearings
 

Thanks to everyone for your comments and insights. I think I’ll stick with Babbitt bearings.

Re: Roller cam bearings
 

DING DING DING We have a winner. A few years ago I talked to one of the guys at Grumpy Jenkins shop and they said it was night a day difference between Roller cam bearings and using babbit as roller cam bearings produce a lot of unwanted harmonics.

It takes more power to move all those needle bearings VS the cam sliding on a film of oil.

I blue print bore a lot of blocks for 55MM cam journals for other shops and builders babbit seems like the way to go. Also machine some of the OEM 350 blocks to 2.120 and use the GMP-1 cam bearings for BBC journals.

Re: Roller cam bearings
 

Carl

Some years back I had a contract to build Winston West 9.1 comp 390 carbed 358 engines. We were quite sucessful and won several races, every engine we built had roller cam bearings, but also were dry sump. I never saw any weird stuff going on in those engines, they made right at 600 HP. Not going to say there was no harmonics, but we never had problems. We also built some with 55 MM babbit, I never saw any difference on the dyno, I did like getting rid of the oil leaks.

Re: Roller cam bearings
 

Anyone have any experience with roller cam bearings on the street. I have 2 Gen3 hemi aluminum blocks that have been cut for 60mm roller bearings. These are in a cam tunnel so no oil from the top and I don't know if you could put a hole in the bearing cage for oil without hurting the bearing. These are destroked and bored to 305" and Bryant cranks and blocks are cut for LS chevy bearings to get a full thrust bearing for road racing. I was thinking of 1 for a street rod but not sure the bearings would oil enough at low RPM on the street. Any thoughts?

Re: Roller cam bearings
 

Don't let it idle below 1500 rpm.

Re: Roller cam bearings
 

NASCAR engine blocks, have closed camshaft tunnels; therefore, the roller cam bearings, camshaft and lifters were always flooded with oil. The initial idea for the use of roller bearings was to reduce friction. Nevertheless, no one expected valvetrain frequencies and harmonics to generate from its use.

Re: Roller cam bearings
 

Isky "Imperial" camshafts.

Re: Roller cam bearings
 

Junior Johnson was running roller bearings in a stock Chevrolet block in 74. I saw a stock open tunnel block at Smokey Yunicks shop from the 70s or 80s also with roller cam bearings. Maybe Jenkins saw harmonics, but the Nascar guys were cheatin with them before with success.

Re: Roller cam bearings
 

Harmonics are probably always there it is when they magnify become intolerable would think is dependent on operating rpm. Friend had severe believe valve train issues with a Ford combination in a Late Model years ago when changing engine builders the second had him take gear away problem solved.

Re: Roller cam bearings
 

They were not cheating with them; it was common knowledge at the time.

The closed tunnel blocks started to show up after Mike Ege, the head of the NASCAR engine shops for Robert Yates Racing and years later, for Roger Penske Racing, built the first closed cam tunnel Ford engine block while working for Yates. Mike later incorporated the same feature on the Chevy and Mopar NASCAR engine blocks while working for Penske.

Re: Roller cam bearings
 

The 55MM bearing you used probably had 3 oil holes = huge oil, A few years ago I had 55MM babbit bearings designed with one oil hole and a groove.

A lot of my customers have said going from Roller to babbit once the adjust the valves nothing changes in lash going to babbit which is good indicator there is less harmonics having the cam floating film of oil VS iron to iron.