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Fitting Electric start to DM2: Advice please.


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All those of a nervous or sensitive disposition, look away now.

 

After trying very hard to put it off, I'm reaching the point of fitting electric start to Bellatrix's engine.

 

Yes, I know she's been fine for eighty-odd years without it; and yes it's satisfying and fun to start by hand on a nice day when the engine is warmed up - but on a cold morning, when she hasn't run for a while, even if you've followed the RN handbook advice to leave little oil in the cylinders, you've used tilley-wicks, and even a blow lamp down the inlet manifold, it's a b**tard!  And possibly dangerous for someone not in the first (or even second) flush of youth; the uncomfortable feeling in the chest might be to do with having toast BEFORE trying to start the engine, but then again . . .

 

I've found a marine engineering firm that will machine the flywheel.

 

What I need is the experience and advice of anyone who has done this conversion - particularly where do you get a starter ring gear for a 22inch flywheel, and what is a suitable currently-produced starter motor (12volt).

 

Any and all suggestions gratefully received.

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45 minutes ago, David Mack said:

Marine Power Services can do you a 23 inch ring gear (at a price).

https://www.marinepowerservices.co.uk/index.php/store/lister/product/jp-js-jk-starter-ring

Mmm, thanks.Followed the link. See what you mean by "at a price"

 

3 minutes ago, Markinaboat said:

May also be worth a call to Dave Bixter at Granthams Bridge, Hillmorton as he's the RN guru.

Yes,after days scouring the Internet this may be the way to go. Ring gears seem to be advertised by vehicle they are meant for, rather than by size. Bit like when you try to buy a car tail lamp bulb.

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Its a problem getting a ring gear and as for machining a flywheel well as the owner of a little Myford lathe that beggars belief. I would look at getting a nice big flywheel with a good ring gear and starter motor off a scrap something or other (with the right voltage) then  getting a thick alumimium disc machined to a suitable dia. and bolting the whole lot to the front of the flywheel. Biggest problem is clearance for the starter pinion but stand off bolts or something plus the aluminium disc would maybe work. A bit of paint and a professional looking safety guard and it would look perfect.

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9 minutes ago, Bee said:

 and as for machining a flywheel well as the owner of a little Myford lathe that beggars belief.

Could you not bolt your Myford toolpost to the engine beds and have an assistant turn the engine over on the hand start, to machine the flywheel insitu, then remove it to fit the ring gear.

13 minutes ago, Bee said:

I would look at getting a nice big flywheel with a good ring gear and starter motor off a scrap something or other (with the right voltage) then  getting a thick alumimium disc machined to a suitable dia. and bolting the whole lot to the front of the flywheel

That would probably require you to have the starter motor mounted backwards, in front of the flywheel assembly (unless your acquired flywheel is larger than the RN one). Not impossible, but a bit clumsy, and you would need the opposite hand starter motor.

 

You can get bolt on starter rings, so you might be able to drill and tap the back face of the flywheel and bolt one on there.

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Problems, problems. I am not machining a great big flywheel at 3 rpm!   The back face would be much better, didn't realise you could get bolt on starter rings. I rigged electric start on an old Ailsa Craig years ago, motorbike chains straight onto the ratchet on the flywheel Worked beautifully about 10 times then the ratchet housing fell apart and the chain nearly took my head off. 

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I would suggest a solid tyre friction drive onto the flywheel using a motor mounted on a pivot so that you could swing it clear. You would need to decompress and rig a way of holding the motor in engagement for starting.

 

Inelegant but easier to engineer.

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1 hour ago, Bee said:

Problems, problems. I am not machining a great big flywheel at 3 rpm!   

Grey cast iron should be cut at a surface speed of 50-80 feet per minute. A 22 inch flywheel has a circumference of about 5.8 feet, so should be turned at about 9-14 rpm. That sounds easily doable on the hand start. It is after all essentially what the machining boys will do.

Edited by David Mack
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1 hour ago, Bee said:

The back face would be much better, didn't realise you could get bolt on starter rings.

A quick search produced this. You might be able to find a larger diameter version.

https://www.diycarserviceparts.co.uk/starter-ring-gear-flywheel-11723-by-febi-bilstein.html?gclid=Cj0KCQjw16KFBhCgARIsALB0g8IrqrgHI0PyeAxUsyakAjT3mNnwI2Gl5J3-nrSI5bvE8AvO5vrOguEaAoPiEALw_wcB

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I've got two or three starter motors taken off lorry sized six cylinder engines that were used for research so the starters are all but new if it helps.

 

That flywheel weighs in at about 300lbs. Not a weight to be taken lightly . . .  Don't ask how I know but it involves an old Standard 10 saloon and a trip to Southampton..

 

Given the  cost, not unreasonable given the amount of work for what is effectively a one-off, for a purpose made ring gear it might be worth hunting for something a tad bigger and having an adaptor ring made.

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On 22/05/2021 at 15:29, Markinaboat said:

May also be worth a call to Dave Bixter at Granthams Bridge, Hillmorton as he's the RN guru.

Unfortunately Dave's a bit crook at the moment so he may not answer the phone.  Perhaps give Deborah Bixter a call at Willow Wren instead.

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Electric start was fitted to Daphne's National by the RN company, perhaps 12 years ago? It involved sending the  heavy flywheel away for machining and ring fitting. A special bracket fabricated for the motor which ,I believe, is different for National or RN, though the RN one might be a standard part. The set up worked ok but it was found necessary to adjust the starter motor with shims to get reliable engagement rather than that often heard "clunk" then nothing until the engine was manually turned slightly. The electric start is reliable now as long as the battery is ok.

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On 22/05/2021 at 20:05, Tonka said:

Just been looking on Tony Redshaw's of Braunston facebook page and they did one for a Gardner engine once so maybe worth a call

I can recommend Redshaw's. They put an electric start on my JP a few years ago.

 

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Somewhere back in the mists of time there was a thread on here by Caspar Ghost who had adapted a volvo flywheel and starter motor to a vintage diesel. It was an ingenious solution using stock automotive parts.  

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Many thanks to all, for comments and suggestions.

 

Plenty to think about there.

 

I will report back.

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  • 1 month later...

I'm currently fitting a starter ring gear that bolts on all adapters made will go with a 2kw starter motor, you can take most starter motors and have a new gear put on them so you could use a lorry one, and convert to fit,

Mine is being made as bolt on so only machine work was a few days in the lathe, I'll take pics if wanted, my plan is to turn by hand then kick starter in to start.

Use decomposition levers still so your only turning over semi weight to speed not dead start.

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