The Use Of Oversized Lower Cam Outer Bearings?

Have you done a search on the later 308QV/328 larger outer bearing size "SKF 630647" (special F only) for those threads (and the threads they reference)? Seems like a huge amount of work for not much benefit -- but JMO.

 

The later bearings did last longer but are a non standard size and a lot more expensive. The 40 mm bearings did a great job and really are very likely to only need to be replaced once or twice in the life of the engine provided good quality parts are used. Replacing the outer bearing, the only one that really wears out is a simple job. Does not really make sense to me to take the motor out, apart and perform the conversion for such a small benefit.

 

Yes, a benefit, but it's not like a bunch of late 308 carb, 308i-2V, and early 308QV are having a huge problem in this area with the 40mm bearing. This change hits me more as a slight improvement that they were implementing into the 328 design and realized that they could put it into the late 308QV production too without a lot of grief/effort rather than being a change to address a critical problem. Are you having a specific problem in this area?

 

At this point in the cars life and the amount the fleet as a whole is driven I suspect seals are probably going to get hard from age and require replacement more than bearings wearing out and replacing one means replacing the other anyway.

 

Didn't that happen already about 15 years ago

I meant more is he having a specific problem that isn't just a normal wear/tear/service issue.

 

No question and why we need to adjust our focus from wearing out to aging out.

 

PM Scott McGehee aka smg2. I remember that thread you were talking about.

 

They don't and the water pumps are not too small either. The bearings only have a high failure rate when poor quality bearings are used or if belts are habitually over tightened. In 40 year of professionally repairing Ferraris I can count on my fingers and toes how many bad lower drive bearings I have replaced. That includes engine overhauls. If someone has done more they are doing something wrong.

The front covers are machined to a specific block. They are not interchangeable with any other block.

You are trying to fix that which is not broken.

 

I looked at changing to the bigger bearings but the earlier timing covers don’t have enough metal around the 40mm bearing. The best bearings I found were NTN 6203LLUA1C4 with L627 grrease (Mobil Polyrex EM, -20F-350F!) I found them from a Toronto supplier (ontariobelting.com) for about $16 and about $18 at my local bearing shop

 

Hello all,
Why don't you use SKF Explorer bearings? My 328 uses the 44mm odd sized and expensive bearings...I could only find them made by SKF.

Just my opinion

John.

 

I had the whole bearings job done during winter 1998/1999 at 85.000kms by an official workshop for huge $$$$.
Information on the www was sparse back then and FChat was just freshly launched IRRC.
The engine came out, transmission separated and the drysump pump got dismantled. Reason for my badly leaking engine was the seal ring behind the outer bearing (I have the later design). Amazing. The inner diameter had shrunk about 1mm and had no contact to the shaft's sealing surface at all. Bearings were still perfectly o.k.
With the informations a have today I would have saved a lot of money doing the easy job myself.

P.S.: Repeated bearing failure might be caused by ignoring the fact, that you need C4 bearings down there. Some independent parts dealers don't even know about the differences regarding the bearing play classes.

Best from Germany
Martin

 

Like tires.