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jeff2wings
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  • 1 year later...

jeff2wings,

Firstly, let me say I'm in awe of the various engine project you have restored, modified and made.  You must have the patience of a saint!

Secondly, with reference to your Micron/Owat-type engine, I wondered if you have seen the article on piston/cylinder finishing by Ken Croft, published on Adrian Duncan's modelaeroengines.com website?  Quite by chance I was only reading it last night.  Ken makes some interesting points about tapered bores and how to achieve them.

Ken Croft on Piston/Cylinder finishing
 

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Oh,hello,thought it was just me here, lol ! Robin, yes I know of Ken Croft from the model engine news website, in fact it was the motor boys plans handbook that Ken made available on the outerzone website that provided the necessary information to build the engine, although I have visited Adrian's website I had not seen that article, it would seem that I was doing all the right things, but not necessarily in the right order! Hopefully the next set of pistons will be better, thanks for the link. 

Before makeing a new piston I  thought it would be worth attempting to salvage the old one by "cherry bombing "it and lapping back to the size it should be. 

20211219_152203.jpg

20211219_152314.jpg

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  • 2 weeks later...
  • 4 weeks later...

Will have to read all this interesting thread...

 

Anyone got a frog 150 R ?

 

With or without a fitted silencer ?

 

Would you know the actual diameter of the cylinder base threaded area, where it screws into the c/ case please ?

 

Anyone happen to know if the silencer similar to the circular Cox 09 type was fitted "alloy up" or alloy down please.

 

Been hunting for a picture to clarify orientation, but no luck.

 

ED, if I were to email you with description and pictures, would you give me the benefit of your opinion.please ?

 

 

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Frog 150 R

 

Thanks Jeff much appreciated.

 

Mine doesn't have the "bee hive" shaped cooling jacket, it has verticaly parallel sided find.

 

It came with silencer ring fitted, label on box and gaurantee slip confirms engine number, 150R w/s, with silencer, slip not dated.

 

Gaurantee slip and engine number tally at approx 1200, so may be an early-ish one ?

 

How easy was it for you to remove the cylinder, c spanner and some heat ?

 

Will measure up in a few days...

 

Suspect either silencer up side down ( the back plate was ) or washer missing. Tiny contact area spigot on cooling jacket to nip alloy ring in place.

 

The spigot does not fit in the alloy exhaust ring, looks wrong to me.

 

Thanks for the dimensions and sorry to hijack your thread which I will read from the begining.

Edited by Rich Griff
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Rich If your Frog has strait sided fins then it's a later Mk2 version from the early to mid sixties I think. All the early models had the round or beehive shaped head. Really early ones were plain silver and later we're anodised blue. The frog silencer muffler fits alloy side up. I have one with a set of the instructions somewhere . If I find them I'll scan and print them here. If the piston is  not scored then "cherry bombing" the piston could get its compression  back. Start another thread for the frog ?

 

Jeff2Wings. Brilliant repair to the Webra front housing. What alloy rods did you use ?  Obviously better alloy used on Webra cases than on the CS Boddo I melted ! Excellent work .?

E.D.

Edited by Engine Doctor
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