Unrestored 102 SD (Naval?)

[Beagle2]

I'm trying to confirm if this crank is original. I suspect it isn't, but need to be sure. It may be from a Century.

If an original SD crank is shorter, it may explain the chunky washer I found under the flywheel plate (flywheel nut may of run out of thread)?

If anyone has a spare crank to measure I would be very grateful.

[woodbutchergraham]

From my brief experience and I’m fairly convinced you are right. The crank on mine is black steel, welded along the counter weights not as yours is cast and all too nice. I’m sure someone has a photo to compare.I’m sure Jan or one of the SD specialists has a spare crank and con rod to help you out. That is if John hasn’t one in his expansive collection of spares

[Oyster 49]

I fished out the spare AD crank I have and compared it with a rusty SDcrank I have. The cranks seem to be the same. I then put the AD crank in a pair of SD crankcases and it fits perfectly. So the conclusion is that later 102 cranks can be fitted SDs

I suspect that is a century crank, con rod and piston you have there.

[Niander101]

Yes obviously original crank was worn out so replaced by the later one
maybe it was run short of oil
i have come across a few now with worn big ends

[Oyster 49]

This is the AD crank I have, not the best condition, some corrosion pitting on one side, but no real depth to it. Big end seems ok.

[Niander101]

Life in that yet

[Beagle2]

Sorry oyster, missed your post

Thanks for the crank photos. However I Jan has managed to kindly source the parts I needed for the power head.

I would still be very interested in buying an SD prop and gear box if you still have a spare?

[Oyster 49]

Yes, I have several. I will look under my workbench..

[Beagle2]

The block and crankcase has gone back together OK. Although there was still slight rubbing from the edges of the con-rod bolts on the crankcase (see earlier in this thread). This is despite now using an original 102 crank and rod. A bit of wet and dry paper got it running smoothly. I guess it was a just down to a particularity tight crankcase? (hope so)

A friend at work tested the block crank and rod etc using Magnetic Particle Inspection ink (MPI). No surface cracks found, so all good. (Thanks Jan!)

I assembled the crankcase using a tiny run of Hylomar. I decided to buy some proper wire twisting pliers to finish the con-rod bolts. May have been over the top, but are useful for motorbikes etc.

I reassembled the magneto. Those screws on the irons needed the tops drilling off as were stuck fast. Took a long time but worked out OK. I wonder why the irons are much bigger than the later MK1 Villiers ignition with the smaller 'cheeks'? Also noted there is nothing to stop the coil rotating on the irons, hereby becoming disconnected from the HT lead. The later MK1 has screws to lock the coil in place. However the coil is tightly sandwiched between the irons so hopefully this wont be a problem.

Now the main problem....

As mentioned at the start of this thread, I mentioned the large washer under the magneto base plate. It seems that without the washer, the flywheel will not sit low enough to cover the base plate (see pic). With it screwed down all the way there is still a 1-2mm gap.

The flywheel will simply will not go any lower on the taper of the crank shaft. At first I thought the woodruff key was interfering, so I trial fitted without it in place. It still sits too high.

Something is not right Any ideas?

I noticed a previous owner decided to attempt to remove the fly wheel by hitting the outer edges. Groan. Although, I doubt this would have compacted the flywheel sides enough to cause this problem.

[Collector Inspector]

Check these

B

[Collector Inspector]

and..............................

[Collector Inspector]

and the very most important to check (your other clearance problem) would be these

Everything should be close if not in proportion

Think "trying to remove crank float" by someone else?????????????????????????????????

Engine checked is SD6226L3

B

[Oyster 49]

Has the crankcase been machined back for some reason? Could this just be a case of a maching error from new, and a washer was put in to fill the gap?

I'll check my SDs to see what they look like gap wise.

However if the screw locates in the dimple and the backplate is then in the right place re the flywheel, then you could just refit the washer?

If all else fails I've got a spare set of casings you can use as a comparison.

[Oyster 49]

These are my two SDs, plus a pic of one now sold. Quite a variation between the three. this leads me to suspect that the casing machining was not very accurate, but the machining of the location dimple seems to be the key to the fit. So if the dimple machining was accurate, but the machining of the backplate location flange was not, then that would expalin the variation.

Seagull were obviously not using statistical process control

Another thought, has the flywheel lower face been machined?

[skyetoyman]

from my days as a metal turner , getting a consistant fit on tapers is difficult. Mainly due to machining tolerances.