Farm Boy 475

[petep]

[ame]https://www.youtube.com/watch?v=DJ5ZZ3AEdkA[/ame]

After 14 months of building it is going beautifully. The build was definitely at my limit of capability, being self taught and only starting ME 4 years ago. I now have the confidence to try something more complicated.
It is running at about 600RPM and fires every 46 revs.
I'm running it in at the moment and have to remake the carb to correct specs - the current carb is a temp job.
Apologies for the poor quality iPhone video. When its painted, polished and base made, I'll do a decent video.
I have 2 questions gentlemen:
1. It has a huge 'kick' when firing, so what sort of base with some sort of 'cushioning' would you recommend?
2. I'd like to simulate the 'casting' look for the base. How can I achieve that?
Best regards to you all and thank YOU all - you have taught me what I know today.
Pete

 

[kvom]

That's a nice runner. The kick looks quite sedate considering others I've seen.

 

[gbritnell]

It certainly runs very nicely. As for a base I would just use a piece of aluminum plate and radius the edges. It doesn't look like it kicks as badly as some others I've seen.
gbritnell

 

[Blogwitch]

A couple of ways you can simulate casting finish.These are what I use.

The first is grit blasting, which works very well on aluminium and softer materials, by using different grades of grit, you can obtain rougher or smoother finishes. The smoothest being small glass bead medium, this gives a finish like you see on commercial model aircraft engines.

I am a devil when I make from castings, especially if they are bad or bent, I will machine everything straight until I can get good datums then apply the simulated release tapers and casting finish when the job is done.

The second method is to use a pneumatic paint remover, the ones with needles shooting in and out. These can get a good casting finish on harder materials such as cast iron and steel. Only done one using this method and it turned out better than I thought it would. There are dual ones on the market, primarily used as an air chisel, but comes with an attachment that converts it into a paint chipper. I sharpened the needle tips to give better penetration and finish.

http://www.ebay.co.uk/itm/150mm-AIR...867319?hash=item58d3764bf7:g:Z7AAAOSwZ1lWgl0e

Hope this helps

John

 

[cwelkie]

Terrific runner Pete! You've done yourself proud this engine runs beautifully. As others have mentioned, it doesn't seem to "kick" any worst than others, in fact seems rather sedate (but that may be down to how well you've "tied it down").

Some have simulated a cast surface using an electric engraver. It will take longer than John's suggestion above but sometimes we have one tool and not another. Remembering to mask surfaces you'd like to remain smooth is usually a good idea ... for the seemingly inevitable slip or two.

Charlie

 

[Jasonb]

Nice running engine.

I have also used an electric engraver but only to restore the cast surface of relatively small castings and it would take quite a while to do something the size of yours.

Another method I have used is to use an old tin of red oxid eprimer that was getting a bit thick and with a short haired paintbrush stipple the primer on and then spray as normal over the top. This gives quite a subtle texture. A splatter cap on an airbrush combined with low pressure does a similar thing.

 

[petep]

Gentlemen, thank you for the comments and suggestions. John, some excellent suggestions - you wouldn't realise how much I have learned from you on this and other forums. Thank you.
The original video had the wooden base fastened in a large milling vice. Here is a video with the engine sitting on the work bench - not so sedate!
[ame]https://www.youtube.com/watch?v=HhyloPnQuE0[/ame]

 

[Engine maker]

Nice job. you should be proud of that one.

The kick you mention may be because you may have the ignition set a but too far advanced ( firing before or right at top dead center TDC ). It also seems to be running a bit rich because of the exhaust cycling 3 times between coasting. If you get it all perfect it will cycle once between coasting.

I built sn 003and just last year noticed it was acting strange. Upon inspection I noticed the cam was worn about 3/64" of lift. So I made a new one out of drill rod and hardened it. The planets must have smiled at me because it runs better now then it ever has. I showed Alan Howell (Jerry's son) at the Zanesville show it coasting 68-72 revolutions between firings, and when the moon and all the planets align the record I've hit is 76.

Keep up the good work.

Jim G

 

[jayville]

looks good well done...clem

 

[petep]

Jim, thats the leanest that I can get it to run and it's definitely firing at TDC. Yes, I would think that one intake cycle should fire it, but it doesn't. I've tried everything. Very frustrating but at least it runs. New carb made to JH's specs so I don't think thats the problem.
Pete

 

[purpleknif]

For the base, you can probably find "wrinkle finish" spray paint at an auto parts store .

 

[Engine maker]

It will get better as it runs and things settle in. Mine has been running for 8 years now, and just keeps getting better. Let it run for a while and then try to tweak it. I have mine firing about 3-4 degrees after TDC. If you go too far advanced (i.e. before TDC) you wear out the rod bearings premature because of the added pressure.

Jim G

 

[jgedde]

https://www.youtube.com/watch?v=DJ5ZZ3AEdkA

After 14 months of building it is going beautifully. The build was definitely at my limit of capability, being self taught and only starting ME 4 years ago. I now have the confidence to try something more complicated.
It is running at about 600RPM and fires every 46 revs.
I'm running it in at the moment and have to remake the carb to correct specs - the current carb is a temp job.
Apologies for the poor quality iPhone video. When its painted, polished and base made, I'll do a decent video.
I have 2 questions gentlemen:
1. It has a huge 'kick' when firing, so what sort of base with some sort of 'cushioning' would you recommend?
2. I'd like to simulate the 'casting' look for the base. How can I achieve that?
Best regards to you all and thank YOU all - you have taught me what I know today.
Pete

As the builder of Farm Boy 408, I can appreciate what you did building it. Great Job! Yours is indeed very sedate - except when it fires: true violence there! I'd make sure the ignition timing is right. Mine doesn't kick anywhere near as bad. I wonder if you're firing too far before top dead center...

Mine is just sitting on a wooden base and stays put while running. No cushion needed.

John

 

[petep]

Well, its finally done. Took a while to get it going properly after the paint job. Thanks to all of you for your previous responses and suggestions. And of course, the obligatory video - [ame]https://www.youtube.com/watch?v=JJWw3QpB0wI[/ame]