Member postings for Ian Hewson

Hi Geoff, thanks for the info on the piston lapping, I used the method described on AdriansModelAeroEngines.com site where he advises lapping the barrel to a slight taper fit, just nipping at the top, similar to your findings.

My engine will probably never fly, but I do like to do the work to the best of my ability even so.

Appreciate the help you get on here.

Ian

Thanks for that Jason, just looking ahead, got the engine built up to the backplate level, going to do the crank and piston next. Lapped the cylinder with diamond paste from Arc, came up nicely.

Interesting build, makes a change from steam models.

Think I have realised what the nipple on the silencer is for, pressurising the fuel tank to feed the carb, no need for the fuel tubes to the mixing chamber in the backplate?

Another question, do you use any gaskets or sealants, for the cylinder head, engine backplate or block to cylinder?

Neil, you should be an archer with all the strings you have for your bow🤗

Hi Jason

Thanks for your prompt reply, appreciated, so the holes on the liner are the critical ones, and should not be restricted in diameter by the holes in the block when it is fitted?

The 10.5mm exhaust hole was the one that was confusing me as it seems to restrict the port in the liner.

Just measured the plan, and I can now see that the 14.35mm is due to the curvature of the cylinder, didn’t want to bu**er up the block on the last cut.

Ian

A question about the port dimensions, the cylinder block exhaust port is shown as 10.5mm x 5.5mm, whilst the cylinder liner port is shown as 15.285mm x 4.96mm.

How critical are these dimension as the are shown to three places of decimals?

I would have thought that the liner would have been the important dimension for the exhaust, is it to do with back pressure as in a car engine?

As I mentioned before, I have not had any experience with 2 stroke engines.

Bought a few cheap carbide drills at one of the regular stalls at the Midlands Show, tried them on an old hss tool using slowish speeds and feed on the Fobco. They cut without any problems, wish I had bought a few more and had some years ago for jobs such as the above.

Edited By Ian Hewson on 03/01/2019 15:17:57

Edited By Ian Hewson on 03/01/2019 15:18:35

Used to make box spanner’s that way out of conduit, opened up the end of a piece of 1 inch conduit with the ball end of the hammer and then closed it round a 3/4 inch conduit bush.

You could make any length spanner up to 12 foot that way.

I know you should not hammer two hammers together, but we got away with it, but it is not to be recommended.

In the late 50s as an apprentice in the YEB meter test room it was a joke to get the lad to hold the wires of the 1000volt megger, but they could not understand why I could hold on as they wound.

So long as I held tightly I only got a tickle, laugh on them.

It was a different story with the later electronic version though, I could not hold that.

My manual says febris k68

Edited By Ian Hewson on 11/12/2018 19:05:18

And a lot more did!!!!!

What’s that got to do with getting a bargain Mick?🤔

Some people have all the luck David 🤢

Wouldn’t change my refurbished by Myford 254s, lot of wi**y waving goes on about myfords.

Thanks Jason, just noticed the two different threads whilst looking for the best supplier.

Grandfather had a pair, used to play with them in the early 50s, he was a boot and shoe repairer as was his father.

Thanks Peter and Jason

Solid bearing it is then, always good to have advice, just been checking my taps, gues which one I don’t have for the plug lol.

Hi Jason

A couple of people have mentioned fitting ball races as an improvement, wondered if it is worth while?

Would you have the glow plug type handy, never had any experience with model aero engines, but it seems that the glow plugs react similarly to spark plugs in a tuned car engine.

Ian

Just received the plans and ordered some metal to make a start on Firefly, can you say how the ball races were fitted and the type?

This will be my first ic engine, all my others being steam, looking forwards to the build.

Just a note that John Feeney is no longer supplying the metal kits for this engine.

Edited By Ian Hewson on 24/11/2018 11:34:29

So the people who have experience of hole saws were right then?