Sexton R975-C1 a mess

[LRDG]

Originally Posted by Bob Phillips

Malcolm- for whatever little bits its worth- those splayed out cylinder bottoms may be a pain to disassemble but maybe they will have saved the thin cast aluminium that makes up the crankcase. Later engines (eg the -46 helicopter) has much heavier castings in it. It also rated at 600 hp with much more blower and carb action. I cannot tell you about the fins, I always thought they were machined in but I don't know..Bob

Good point, Bob. You are right, they did save a lot of damage to the crankcase.

It's pretty well apart now and disassembly has stopped as there is some angst about repair costs.

There is some interesting damage to the crankcase in the raised web that supports the lifter bores. It's shown below. It lines up exactly with the inboard end of the starter drive shaft (last photo, 6 o'clock position). It's like the nut on the starter end of the shaft had come loose and allowed the shaft and small gear to move inboard and wear into the web. And it doesn't look like old damage because there is wear debris coated on the web that's not shown on the photo. It's like the nut came loose and when it was spotted (or heard), somebody just retightened the nut to pull everything back into place and hoped for the best. The weird thing is there absolutely no sign of damage or wear to the end of the shaft or the gear. It's a bit of a mystery to me.

Thanks again for all the suggestions on parts but things are on hold for a while.

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[Stew Robertson]

Hey Bob ;
I think you should clarify your comments on Bill's 975

[Bob Phillips]

Hi Stew: I think you know this story ...so
Radial engines have a tendency to collect oil in the bottom cylinders and can create a hydrostatic lock up situation if you try to start them without first eliminating any collected oil. Usually you turn the engine through several revolution to evacuate oil from the cylinders or you could remove the spark plugs and drain it. In a tank engine your supposed to handcrank the starter 50 times to turn the engine over ( through the starter reduction) to clear oil. Oil is not compressible. If you crank or are able to start the engine without clearing the oil, you will have major problems- bent link rods, broken pistons, jugs that are fractured off the crankcase etc. The story goes as I heard it was, that once the radial powered vehicle in Bill Greggs collection got away from Rockwood (Bill and Stew), at some later time it was damaged when someone unfamiliar with correct procedures attempted to start it. Anyone familiar with a radial engine would not make this error. WW2 vets told me they would "bump" the engine a little at a time with the electric starter so they would not have to hand crank it.

[Bob Carriere]

On a visit to the farm Bill offered us a drive..... and we cranked and we cranked..... Bill had instrcuted us that the engine needed 100 turn of the crank to get 2 full revolution of the engine and amptly expalined why. After pulling a battery cart that must have weighted half as much as the tank... cables were connected and a laborious starting process began.... took a while for all cylinders to fire in an orderly fashion........ and the oily smoke insured there would be no mosquitoes.

Cheers

Bob C

[Bob Phillips]

Ah the good old days!!
When I first started playing with radial engines a friend and I would start them in his garage with a separate fuel and oil tank. After starting and running the first one we quickly learned that it needed to be attached at the top to a ceiling joist - because that engine just about took off as we cranked on the carb fuel supply before the governor kicked in ! Lots of torque and with magneto ignition a runaway engine would be hard to shut down until it ran out of fuel. By the way all the engines I ever ran had high oil pressure in the 60-70 pounds region while running. We also learned to prime the dry sump oil system thoroughly before running the engine so that we had oil in those weak - link bearings and didn't unintentionally wreck something.

[LRDG]

Just to close the loop on this thread, the R975-C1 engine with its 5 broken connecting rods is now a display engine at the museum. The Sexton remains engineless.
A restorable Centurion is now my focus. The ironic thing is we have four Rolls-Royce Meteor engines in various states of repair here, leading one to assume we could make a good one from all the parts for a reasonable cost. But in reality, the cheapest option seems to be to buy a rebuilt one one from these guys for $10,000. And it comes loaded with all the accessories.

http://www.newenglandboatandmotor.co...gines-for-sale

[chris vickery]

Call them up and offer on trade all the surplus engines and components you have. Might be an easy trade or a minimal investment with little to no work.
If they are in the business of rebuilding and re-using these engines, would be a lot less headaches than trying to rebuild what you have on hand.