1928 Model 9 engine in a 1928 Model 8 frame?

Started by priormuir1, November 17, 2018, 03:19:00 PM

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Tom Snow

Hi, the '28 Model 8 engine is 20.50 inches from the bottom of the crankcase to top of the rocker plate, say 22 inches overall for good measure. As previously stated the 8 and 9 were scaled up or down depending how you look at it , even the petrol tanks have a different depth; about 4 inches for the model 8 and 4.50 inches for the model 9. I would look for model 8 engine pieces or swap the 9 engine as it would make a better job at the end of the day as all of the other parts like primary chain cases would fit and not need modifying.

Regards,

Tom.

wessex_man

Sorry I can't help re-height as I don't have my M8 now. You could try fabricating some temp engine plates in wood or aluminum to drop the engine and see how far out the other alignments are. A case of suck it and see if it's possible. Best of luck.

priormuir1

Many thanks for the reply. I wonder if any kind Forum member might measure the height of a 1928 Model 8 engine? Clearly, I have the choice of either trying to fit my Model 9 engine to the Model 8 frame I have  or I can try to find a 1928 Model 8 engine.

wessex_man

I Think you are going to have extreame difficulties in trying to do so as Marstons scaled their Sunbeam parts.

The 1928 Model 8 frame is much smaller than the Model 9 of the year. You can't spit through the bottom of the tank frame. They also kinked the bottom tube to fit the engine.

If you make modified engine plates to lower the M9 engine, in an attempt to compensate for the extra height, so it doesn't hit the tank. I suspect you will have alignment issues elsewhere.

Not saying it can't be done but if Marston's thought they could have shoe horned a 500cc engine in don't you think they would have tried?

you may get some idea of scale from these.
1928 model 8

1928 model 9

priormuir1

I wonder if any member has fitted a flat tank era model 9 engine in to a similar age model 8 frame? I acquired an incomplete model 8 (which had no engine) and have since acquired a Model 9 engine which I hope might fit. I am looking to take advantage of someone's previous experience!