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This is the first time I have assembled the engine of my ’49 Flyer.
Can anyone give me advice on the best way to go about assembling the cranks and flywheel please.
I had a ‘dry run’ at it last night and with gland springs, shims and the main bearing rollers it seems like you need three pairs of hands !
Is it best to lay the cases on their side and put one web in and then flip the lot over to do the other side or is it best to keep the cases upright and put the webs in from the side ?………. And this is before I’ve even got to the part of knocking the cranks up !!
Any help or advice appreciated.
Sticking the main bearing rollers in position with grease helps, and I also have a couple of useful little tools that came from Tom Ward, via John Hartshorne, about twenty years ago. They are just pieces of hex bar, about three inches long, threaded at one end, that screw into the crankpins and act as handles, and obviously one is threaded L/H and the other R/H. They make it VERY easy to insert the cranks into place one-handed. It is absolutely VITAL that the flywheel is supported laterally when ‘knocking up’ the cranks onto their tapers, and the only way to do that is to have the engine on its side with a solid block of metal supporting the flywheel. The block I use, also ex-Tom Ward, is held in my large bench vice, and I need someone else to hold the engine in place, crank on top of the block, when I knock the other crank, so that both seat onto their tapers. If you fail to do that the hammer impacts will be transmitted onto the main bearing cups, and they WILL be damaged… For lowering cylinders onto the crankcase I use a pair of guide rods. These are just lengths of 3/8″ diameter rod with about 1/2″ of 3/8″ BSCY thread 26TPI on the ends, screwed lightly into the rear pair of holes that will take the cylinder holding-down bolts after assembly. I may do a Yowl article with photos showing these assembly tools…..
Thanks for that advice Brian.
I had read somewhere else about guide rods to help in lowering the barrels on and I intend to make some myself as it is within my engineering abilities.
However I don’t have the means of cutting a left hand thread for the handles you mention. I’ll see what other options I can come up with.
Regarding the ‘knocking up’ of the crank, I bought some Inch and one eighth aluninium billet for the job and had intended to do it as you say with one piece of billet in the vice and using the other piece on top to drive the cranks home, but tell me, how hard do you hit them ? I know this is a difficult question to answer
as everyone has a different understanding of how hard, hard is ! But if you could give any guidance it would be most appreciated.
Also, what end float should I be looking for on the crank when its assembled, and do I have to assemble without the gland springs so I can check end float easily and then dismantle and re-assemble with the springs ? 🙁
Sorry to bombard you with so many questions, Its a steep learning curve for me !!
Thanks for your help, Mark
We are getting into the realms of subjective rather than objective opinions, and how hard to hit something with a hammer is a prime example of that ! I can only suggest good old common sense and a small hammer. All this has been covered before in “Technicalities”, so I strongly advise you to have a good read of the various articles on this subject. End float needs to be around 12 to 15 thou”. The factory end float was 1/64″. It needs to be split evenly between the two halves of the engine. Lever the flywheel over fully to one side with a broad screwdriver between it and the back of the main bearing cup, and measure the clearance. Then lever the flywheel over the other way and measure the gap on the other side. The two measurements should be the same or within a couple of thou”. Again refer to “Technicalities” for more details.
Perhaps I’m lucky. My quite heavy duty vice has jaws that will clamp on the flywheel and still clear the sides of the crankcase enabling me to have both hands free for knocking up the cranks. You don’t need a big hammer for knocking up if the tapers are a good fit. You can check the quality of the fit by just pushing the cranks iinto the flywheel before assembly, you should be able to lift the flywheel by the crank without the flywheel dropping off. Keep your feet clear just in case!
Thank you both for that information, it’s been very helpful and I now feel more confident about the task.
I’ll let you know how I get on.