A question about the best technique for fitting the Navigator and Electra one piece cylinder barrels onto the pistons for experienced Lightweight Owners. I have always found this an incredibly difficult, fiddly, high risk job even with the correct narrow piston ring compressors which I see are now available through the NOC Spares scheme.
With so little room between the 8 studs surrounding the heavily spigotted bores in which to fit and remove the ring compressors and with the skirts of the pistons projecting into the crank case mouths making it difficult to hold the pistons steady at TDC I find it a really difficult job with a high risk of breaking rings.
Looking at it I am wondering if it would be much easier if the 8 studs round the bores were removed leaving the 4 next to the push rod tunnels as guides. Once the barrels are safely in place it should be an easy job to screw the studs back in place.
Can anyone confirm this as a good solution or offer a better way? Many thanks in eager anticipation as I get ready to re-assemble my freshly rebored Navigator barrels!
Cheers. Nick
I think...
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On the bench... cast…
On the bench... cast iron cylinders liners upwards I filed a small chamfer on the inside face of the liner to (perhaps?) ease piston rings into the barrels. With 2 hands free, then fitted the inner gudgeon pin circlip and fitted each piston with rings in the upturned barrels nice and slow with the ring gaps exactly where I wanted them (I did not need a ring compressor)
I then found it easy to offer the barrels to all the pre fitted studs. Propping the cylinder over the crankcase allowed me to have 2 hands free to fit each gudgeon pin to each piston and then the outer gudgeon pin circlip.
If I did the same again I would have stuffed rags between the crankcase opening and the and the conrod while doing so (guess why?). 8,000 miles later all ok so it worked for me.
GRAHAM
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Removing studs
I removed the eight studs around the bores so I could get the ring compressors off the pistons. I also shaped a piece of thin sheet metal that sat across the crank case to support the pistons while persuading them in to the cylinders.
Lots of "Rocol" ASP around the cam followers to stop them falling out!
Once the rings were in the cylinders that left just enough room to remove the protection I put around the polished connecting rods.
I considered Graham S' method but was concerned over the heat needed to expand the pistons to get the gudgeon pins. The gasket and gasket sealant might not like the heat?
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Great feedback Ian, Graham…
Great feedback Ian, Graham and John, many thanks, Andy's advice is always good so studs out it is! On balance I favour John's approach which matches my thinking. Last time I replaced the Electra's barrels I used two thin strips of metal to support the pistons which worked well. I think leaving the 4 push rod studs in to align the base gasket and guide the barrels is worth doing. Luckily the Navigators studs are all new so should come out easily. I will report back once the job is done!
Nick
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... that removing all the studs is what Andy Sochanik and others recommend. The spigots should ensure that the barrels go in the right direction. Although I have to say I haven't had to do this. Yet......