Engine locked up on dyno

[paul_f]

That could be a date code towards the end

[leec]

Any progress on the rebuild?
Lee

[baz]

Still waiting on a crank grind which is holding up proceedings right now. Hopefully done soon so Rob can get on with it.

Feel a bit sick at needing a quality crank messed with already

[baz]

Things are finally moving on getting this fixed, collected the engine yesterday and will start cleaning everything up over the weekend.

I checked the offending rod bearing against a new one, after bending the edges outwards it matches almost perfect so that tells me the bearing is vw journal.
Looking closer at the shell it looks like it started breaking down pretty badly, you can see the pitting in the pic.



Here's what my sump plate looks like, lots of metal!



Looking at the crankcase bearing saddles I can see just over a third of my oil feed openings were intersecting with the grooves in the main bearings.

[Joel Mohr]

Notice the "shape" of the scarred area...the journal wasn't flat...and just an FYI... When I was grinding cranks at Bergs, there was a "racer clearance" that all of the race cranks got... .002 under the low was what Gene wanted...

[Torben Alstrup]

Exactly! today everybody want to build on max spec because they thibnk it is better. Its not, and definitely not in a 45 year old engine. A new Yamaha would be different.

T

[baz]

I'm surprised at a dpr crank not being ground correctly but i can see the bearing shows the journal wasn't flat across the full surface. This would have made a funny shaped plastigauge strip right?  Also mic'ing the journal would have showed it as larger than the others right?

I'll be sure to measure the new crank journals on 3 points across the journals to make sure I don't get the same problem again.

[spanners]

We are drifting onto a crank problem now, It's so unlikely it can be discounted, the facts are the bearings were shite from day one, on top they were not blue printed for race engine use, there is no copper backing, a sure sign of rubbish bearings, we all need to stop looking for supplier price and show cheapskate customers the door, it's so bad now, bearings are the last thing I change, rod bearing possibly, my own race motors have o/e mains with many many hours on them, mains just don't wear with a decent oil filter system, used o/e German is still superior to the available rubbish suppliers WANT TO SELL YOU, it's up to us to stop the rot.

[baz]

What are the new mahle/clevite rod bearings like?

[spanners]

Mahle BE are good, I hear clevite are but have to say I've not used them, Mahle mains on the other hand lack the steel backing for no 2, you can use no3 full bearing at no 2 instead, or you could use a clevite steel no 2 and Mahle remainder,  it's been thus some years now. I would guess your crank journal picked up the bearing material first in the centre area, this then machined out the odd dish look to the bearing.

[spanners]

I Blame the scotch whisky , you can't of cource get the full bearing over the crank....

[baz]

So I'm trying to get the best bearings I can this time round. I've located some old stock mexican mahle cam bearings which I believe should be good quality? Seller says they are heavy tri metal. Any opinions on these?

Also located a set of nos vw in the blue vw box main bearings, they have discoloured over the years to a dark grey  and I'm wondering if they are still good to use?  If they are good to go are they gonna be that much better than the silverline mains?  They ain't cheap but I have no problem paying for quality if it's justified. If however the silverline mains are as good then I'd rather save the unnecessary expense

[richie]

So I'm trying to get the best bearings I can this time round. I've located some old stock mexican mahle cam bearings which I believe should be good quality? Seller says they are heavy tri metal. Any opinions on these?

Also located a set of nos vw in the blue vw box main bearings, they have discoloured over the years to a dark grey  and I'm wondering if they are still good to use?  If they are good to go are they gonna be that much better than the silverline mains?  They ain't cheap but I have no problem paying for quality if it's justified. If however the silverline mains are as good then I'd rather save the unnecessary expense

I got silverline mains and cam bearings in the nitrous 67 and no problem there , have put them in lots of motors[ and the rod bearings] and never had a problem, I wonder if there is just a bad batch of rod bearings. The only problem I have seen is with real cheap chinese rods where the tang cut out on rods was to small for the rod bearing to fit nice, took a little work to get to fit and a better quality rod would have been cheaper after the time spent

Are you using a new crank now? or a ground one? I have some oversize VW journal rod bearings made by Vandervell in the 70s which are really good but no standard sizes.

Are you using dual thrust cam bearings? if so are those Mexican bearing just single thrust?

cheers Richie

[baz]

Hi Richie,  yes the cam bearings are single thrust but he has a few sets and they are reasonably priced so was thinking 2 sets will get me what I need? 

Since my dyno fiasco I've spent hours searching for info on silverline bearings, there isn't a whole lot of negative feedback on them but the bad stuff I've read did apply only to rod bearings being occasionaly tight and cam bearings being somewhat soft.

I bought a new dpr crank as waiting for a regrind was taking an age so I'm back at standard journals again. With the availability of os bearings I'd have been better off holding out for my regrind 

I have a set of silverline mains torqued up in my case I'm gonna measure up today, but the ocd part of me wants those blue box vw bearings now that I've spotted them and they've spoken to me

[alex d]

I had a bad set of Silverline main bearings, but that was back in 2007

[baz]

Scored a few sets of nos blue boxed rod bearings and bought those mexican cam bearings I mentioned earlier. Still undecided on the blue box mains, found some more for sale that look almost like new, nice and shiney and not dark grey like the first ones I found.

[baz]

Some nos ks rod bearings compared to current best available clevite 77.

Ks on left




Ks on right

[baz]

Thought i would post my latest findings just to put this topic to bed. I fitted 3 different sets of nos ks bearings to my rods and measured with a dial bore gauge. All 3 sets measure out at .02 - .03mm bigger than the silverlines that were in my engine. Not having the crank to hand yet so can't measure the journals and calibrate my mics to it but looks for certain i had tight bearings. If my mics are calibrated spot on I'm getting 55.04 to 55.05 on the ks bearings and 55.02 on the silverlines

[Torben Alstrup]

If the crank was/is on max measure, then the Silverline set up would be not enough. If the crank was 2-3/100 under like most new Chinese cranks it should be just fine, unless you want to rev 7000+ rpm. Then i like a little more tolerance too.

T

[baz]

Its a dpr crank which rob took a quick measuremant from the day we stripped the engine, it came out bang on 55mm with his mic.
I've a new dpr now which I'll need to measure with my mic so everything is measured with the same tools, but the supplier has told me they usually always spec out on the high side of the tolerance.