Clevite bearings question.

Lyndon302 · 08-10-2021, 01:59 PM

Are they hard on the crank ???
911 2.0L S . I want to look after my good STD crank.
Lyndon

faapgar · 08-10-2021, 03:49 PM

I have built many short stroke 2.8 motors.My 2.8 is based on a 76-77 turbo case or 76-77 3.0 Carrera case.The early 6 bolt crank is great.If you have any issues with wear or ovality just have it turned down to a 3.2 rod bearing spec.It makes the mass lighter and because the bearing shell is thinner it lasts longer.If there is an issue with the bearing surface the Clevite bearing will wear the crank more than the Glyco.Obvious,the glyco is softer.I prefer the Clevite as if you machine the rod for the correct clearance the Clevite has twice the life.The key is to crossdrill the center main that feeds #2 & 5 rod journal.It should be 25% larger than the hole for the front and back feed to equailize the pressure to the center mains.Gotta go as I am cooking dinner for guests.Ciao Fred

Lyndon302 · 08-10-2021, 10:56 PM

3.2 bearings.
Will they fit my rods ??
How much is the crank ground in thou.
Mine is good STD but it's good knowledge.
Lyndon

Tippy · 08-11-2021, 04:54 AM

Bearings purpose in life is to embed any debris that gets through the oiling system. So no, they are not hard on the crank. Second, Porsche crank journals are hardened as far as I can tell.

Dpmulvan · 08-11-2021, 05:27 AM

Quote:

Originally Posted by Lyndon302

3.2 bearings.
Will they fit my rods ??
How much is the crank ground in thou.
Mine is good STD but it's good knowledge.
Lyndon

Your overthinking everything, we went to clevite or Porsche rod bearings because there was a problem with aftermarket glyco rod bearings ( sizing, failures, quality).
Just go get a set of clevite rod bearings and be done.
Cranks are ground when there’s damage.
If your crank is good it will only need a polish.
Check your rod bushings and replace if needed.
Fitment issues caused by rod big end wear are usually corrected on the rod by removing material and remachining the big end.