V-twin oscillator steam passages?

This topic has 6 replies, 2 voices, and was last updated 12 February 2012 at 22:17 by Cornish Jack.

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11 February 2012 at 11:24 #84384
Cornish Jack
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@cornishjack
G’Day all.

I’ve nearly finished mangling the bits for the Blackgates V-twin. General incompetence has reduced the dimensions of the standards to less than the drawings and I have still to complete the air/steam passages. Having some difficulty visualising the ‘cycle sequence’, particularly in respect of the line-up of cylinder ports against standard ports … it appears that the two coincide fully at half stroke – seems odd to someone who vaguely understands the Otto cycle!!

The relative size of the ports is such as to, apparently, require great positional/angular accuracy. I would find this much easier to accomplish if the ports for the standards were drilled on separate ‘facing’ plates, attached to the standard surface with the air passages milled out. This would also help with the reduced thickness of the standard. Could anyone who understands such things please comment on the feasibility/stupidity of such a scheme?

Rgds

Bill

PS – this engine, if ever complete, will NOT run on steam!!
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11 February 2012 at 11:24 #5941
Cornish Jack
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@cornishjack
12 February 2012 at 13:04 #84516
Cornish Jack
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@cornishjack
Hmm, no response as yet. Probably Les Jones 1 was right – that piccies are needed.

Sooo …

The difficulty, as given in the previous, is accuracy. How necessary and would my suggested variation work?

TIA

Rgds

Bill
12 February 2012 at 14:34 #84527
MICHAEL WILLIAMS
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@michaelwilliams41215
Hi Bill ,

There is no problem at all in fitting separate port plates to an engine – indeed it is commonly done . You might like to fix with a few small screws initially so that you could if needs be have more than one go at it . When all is ok seal up with small amount of solder or ordinary sealant – taking care not to block anything up . My preference would be a Loctite gasket type sealant .

You might like to make the actual ports a little undersize to start with and enlarge them when you are sure they are in right place . Most engines of this type actually work quite well or even better with undersize ports anyway and the need for accuracy is less .

If you find that the existing standard and the port face together are still not thick enough for your needs there is no reason not to put a washer behind the crank and space the whole lot forward a little .

Ask any further questions you like .

MW
12 February 2012 at 17:29 #84541
Cornish Jack
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@cornishjack
Thank you, Michael.

Will give it a go. Some further puzzlement – The inlet holes on the cylinders are specified as No 50 and the holes on the standards are spec’ced No 60; would that take care of your suggested port sizing?

Rgds

Bill
12 February 2012 at 17:44 #84542
MICHAEL WILLIAMS
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@michaelwilliams41215
Hi Bill ,

I’ve studied the drawings a bit more .

The designer of your engine seems to have a good understanding of what is needed in way of port size and spacing . I suggest you make them as drawn .

MW
12 February 2012 at 22:17 #84574
Cornish Jack
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@cornishjack
Thank you, Michael – that’s reassuring

Rgds

Bill
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