Roller cam bearings

[HP HUNTER]

Originally Posted by carl hinkson

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.

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.

[Stewart Way]

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?

[Glenn Briglio]

Originally Posted by Stewart Way

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?

Don't let it idle below 1500 rpm.

[SSDiv6]

Originally Posted by HP HUNTER

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.

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.

[Dwight Southerland]

Isky "Imperial" camshafts.

[1347]

Originally Posted by SSDiv6

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.

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.

[Signman]

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.

[SSDiv6]

Originally Posted by 1347

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.

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.

[carl hinkson]

Originally Posted by HP HUNTER

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.

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.