Quote:
Originally Posted by mikedsilva
For what it's worth, I use boregauges, micrometers and plastigauge to double check.
For a street/home build, plastigauge is more than acceptable. I've never had success being able to do the rods with plastigauge though.. not sure how people manage to torque the rod bolts without the rod moving.. maybe that's me? I always use mics and bore gauges.
I never re-use bearings. I've only once or twice come across bearings with zero marks or wear. And even if they look perfect, I just cannot bring myself to re-use them. For your rods, def do not use the Glyco bearings. Use the Automobile Associates style or if available, look for ACL bearings. They come in std size and "extra clearance" sizing and they are extremely accurate.
For the mains, the Glyco tend to be ok but I usually go with Gen Porsche GT3 main bearings.
When you bolt your case halves together with the crank, make sure to use the #8 bearing too. It is the "locating dowel" at that end of the case.
I target 2 thou clearance on mains and rods.
As sturdy as the aluminium cases are (compared to Magnesium), I've never come across one that measures within the Porsche spec of 65.00-65.019 mm. Never.
People say that Alusil cannot be re-ringed cos Wayne's book says so. Others have done it. Some successfully. Some not. I have not come across a client willing to take the risk yet. So I have the cylinder replaced or re-plated with Nikasil and get replacement pistons and suitable rings.
If you look at the parts listings on this site for rings, they say they are suitable for BOTH Mahle and KS cylinders.. but how can that be possible?
Others have said they buy them from here, but when I have asked for part numbers so I can order some, the trail goes dry... I tried speaking to the reps at this site, but they couldn't assist.
As for Alusil being no good, well, it is used widely in lots of other makes and lots of other Porsches. I recently rebuilt a 3.0 with Alusil.. it had travelled 250,000 kms. The cylinders looked like new and the rings were also in great condition.
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OG911,
READ AND PRINT THE ABOVE POST (by
mikedsilva). You would probably not get a better recommendation than this one. The most expensive costs or expenses in engine rebuilding are LABOR, cylinder heads machine work, quality main and rod bearings, and heaven forbids crankshaft work. Since you are doing the rebuild yourself, why use old bearings with 220,000 miles on them? Alusil cylinders in good condition could be re-ringed. PROOF: I have in the garage a ‘78 SC track car with almost 20,000 track miles rebuilt more than 25 years ago and still running well plus more than a dozen engines I had rebuilt and counting.
You will need to use precision metrology tools to measure the bearing clearances. I could not imagine bringing my car to a shop or mechanic that has no tools and using tape measures for precision evaluation. Wish you good luck.
Tony