Hill engineering timing bearings

The part of my tach above 7800RPM is ORANGE on the way to RED???
Not much power to be realized past that, anyway ...

IMO only, the traceable Hill bearings are 'as good as it gets" in todays marketplace.

Ricambi is a sponsor here, and may pop in with some more info on them...

 

The cams spin at 1/2 the speed of the crank or the the lower drive pully due to the cam pullies being twice the size of the lower drive pully. I do not remeber the ratio but if you divide the diameter of the lower drive pully by the diameter of the bearing and multiply by 7700 you will get the max speed the bearing will achieve on your engine. If I am recalling it correctly it was 57XX RPM

 

Definitely contact Daniel at Ricambi America. He can answer any of your questions about those bearings, and supply them to you. Next belt change on my 328, I'm definitely buying those bearings from Daniel!!!!

 

I wouldn't get too worried about that labeling on the bearing as it can be a shortened/incomplete form of the whole PN. Yes, those are double row angular contact ball bearing as shown on page B-62 (page 168 in the pdf) in the NTN catalog -- I'd also guess that the "CLD" is some sort of contraction of "C", defining the contact angle, and "LLD", non-contacting seals, but it could also just be something not listed in their "standard" catalog.

MNExotics is on the right track for the RPM, but there's also a 4:3 gear reduction between the crankshaft and the belt drive sprocket:

tensioner RPM = 3/4 * crankshaft RPM * (belt drive sprocket OD)/(tensioner bearing OD)

I don't have the exact OD dimensions handy, but they are not hugely different, so MNExotics's ~6K RPM guesstimate (when the crankshaft is at 7700 RPM) is in the right ballpark.

 

I was going to leave it to you guys to work the actual spinning RPM out, I knew it wasn't 1:1......

 

I did some research on best bearing for the buck last year and ended up buying a set of the Hills. I dont think you can do better without going to some HP race type bearings and pay out the wazoo for them. I think the Hills are the way to go. They are going on with my next belt change in a few weeks.

 

It was awhile ago I did my math but I have a 308 engine out at home I will have to measure again. Anyone looking for a spare mill and tranmission?

 

What year??

 

Maybe we should look into what Hondas use for timing belt bearings. They seem to last a very long time and also rev pretty high. Seems to make sense that they could be similar in quality, right?

 

You're making the problem harder than it needs to be. No matter what's going on with the drive sprocket, we know that the camshaft RPM is half of what the tach indicates. So no need to consider the gear reduction or drive sprocket at all - just take the cam sprocket OD, divide by the tensioner OD, multiply by half the the RPM, and you've got the tensioner RPM. That's the same calculation you'd do even if the belt were driven directly off the crankshaft.

 

No, it's not "harder" -- you've given an equivalent calculation that is exactly identical in complexity:

tensioner RPM = 1/2 * crankshaft RPM * (cam sprocket OD)/(tensioner bearing OD)

Please explain how this equivalent equation is any simplier/different?

 

Simpler for me because all I have to know is that the camshaft turns at half-speed on all 4-cycle engines, instead of having to go digging through the fchat archives because I'm not 100% sure that I've remembered the Ferrari-specific 3:4 ratio properly. Of course the answer has to come out the same either way.

 

That's a different issue

 

A+
2.0 * 0.5 = 1

Or, count Cog Teeth.
It is sort of digital, I like that.
( I have worked on a bicycle.)

Seems that the Lower Drive Cogs, tensioner bearings, and crank,,, all have the same RPM, for the lower drive cog dia. = bearing dia ,,, approximately.
or not.
Edwardo