Author Topic: RLE questions!  (Read 20084 times)

Offline Alyn Foundry

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Re: RLE questions!
« Reply #135 on: February 22, 2018, 11:16:34 AM »
Good morning John.

Busy day, yesterday sorry for my late reply.

Yes, Phosphor Bronze. Before the days of Stainless Steel they were used widely in systems that needed a corrosion resistant non return valve. Stainless is a good alternative.

As for lengthening the jet block to suit your fuel tank, yes thatís exactly what I would do.

Your genuine OEM part should reach you in a few days....  :)

Cheers Graham.

Offline Manorfarmdenton

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Re: RLE questions!
« Reply #136 on: February 22, 2018, 01:38:53 PM »
Hello Graham,

Thanks - I'm looking forward to setting eyes on the now-famous coating on it!

Take care,
John.
John Fearnley

Offline Manorfarmdenton

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Re: RLE questions!
« Reply #137 on: March 13, 2018, 02:21:01 PM »
Graham, is it critical how far the 3/16" diameter end of the jet block with its 1/16" needle hole projects into the 7/32" passage in the main body?  As machined mine is just flush if I seat the jet block on a soft washer, or can stick out into the passage by a gnat's wotsit if I leave the (unnecessary) washer off.  Its just a matter of machining a bit off somewhere if that isn't enough - i.e. to cause some sort of venturi effect.  When I've soldered the top on the tank all that's left to do is the woodwork.  John.
John Fearnley

Offline Alyn Foundry

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Re: RLE questions!
« Reply #138 on: March 13, 2018, 04:12:35 PM »
Hi John.

The Gnats whisker is fine!  ;)

Better to slightly protrude....

Cheers Graham.

Offline Manorfarmdenton

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Re: RLE questions!
« Reply #139 on: March 13, 2018, 04:54:46 PM »
Thanks Graham.  A gnat's whisker it is - I thought that washer wasn't necessary  :)

I've just made the mixture screw.  I'm very near the point where I find out if it works!  Fingers crossed.

John.
John Fearnley

Offline Alyn Foundry

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Re: RLE questions!
« Reply #140 on: March 13, 2018, 05:00:48 PM »
Hi John.

A first run? How exciting, there's few things to match !

Your " choke " is simply a finger placed over the front of the carburettor for one pull on induction.

Next pull should, if all's set right, see it running. Get ready for an ignition stop if the governor doesn't get the speed to regulate at around 450 RPM.

Cheers Graham.

Offline Manorfarmdenton

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Re: RLE questions!
« Reply #141 on: March 13, 2018, 11:21:49 PM »
Hi Graham,

Good thinking about stopping the spark.  I'll just screw the engine down to a board for testing so the ignition unit and battery box will just be lying about.

Yes its quite a feeling of achievement when they run for the first time.

John.
John Fearnley

Offline Manorfarmdenton

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Re: RLE questions!
« Reply #142 on: March 15, 2018, 06:08:22 PM »
It runs Graham!  Initially it didn't have great compression, but after a few minutes running that's no longer a problem.  In fact there might be a tad much as the engine - complete with flat board its attached to for testing - jumps around all over the living room floor (wife is supportive but the poodles are decidedly suspicious).  I can't start it by pulling the flywheels yet, but it goes every time when spun with cordless drill and three-pronged adaptor I made to go between the flywheel spokes.  I'll try to do a vid over the weekend.

John.
John Fearnley

Offline Jasonb

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Re: RLE questions!
« Reply #143 on: March 15, 2018, 06:29:09 PM »
Thats what we like to hear, well done.

If the jumping about (the engine not you) gets too much you may want to think about taking a bit of weight out of the flywheel rim, several engines I have made have had this on the drawings and match full size.


Offline Manorfarmdenton

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Re: RLE questions!
« Reply #144 on: March 15, 2018, 10:10:01 PM »
Thanks Jason.  Actually, I'm not sure which of us was jumping about more - the engine or me.

Good idea about adjusting the flywheels.  Presumably it was done with a ball-nosed endmill?  If its weight-removal it would be diametrically opposite to where added weight would be?  I'll refer to the Red Wings, which hardly jump at all. 

Another issue that comes to mind is the compression ratio of course, and I was warned that a higher ratio would cause jumping was I not!  It hasn't come right up yet, only having run very briefly, but presumably soon will.  I wonder whether lowering it would help, and do you think that would make starting easier too?  I still can only start it with the drill.  Its easy enough to reduce it as I used a Red Wing pattern piston with three rings, so I could easily turn the top ring groove off thus shortening the stroke by about .25".
John Fearnley

Offline Jasonb

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Re: RLE questions!
« Reply #145 on: March 16, 2018, 07:29:16 AM »
Have you tried adjusting the timing when it is running to see if advancing or retarding calms it down a bit?

Offline MJM460

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Re: RLE questions!
« Reply #146 on: March 16, 2018, 10:42:55 AM »
I don't know what clearance volume you have at top dead centre, but I am wondering if 0.25 inches might be way to much to take off in one step for the reduction you are thinking of.

Compression ratio is the ratio of swept volume plus clearance volume to the clearance volume, so it is all about how that 0.25" compares with the the current clearance.  Would it be better to take it off in two or three steps?

MJM460
The more I learn, the more I find that I still have to learn!

Offline Alyn Foundry

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Re: RLE questions!
« Reply #147 on: March 16, 2018, 11:03:59 AM »
Good morning John.

I'm sorry I didn't reply sooner to share in your success, very well done!!

You could say it was 30+ years in the making....

Two things, Jason has already touched on one. Ignition timing. Try retarding it, a bit at a time. The second one which might make all the difference, richen the mixture. As you can't start the engine by simply pulling the flywheels over TDC it suggests to me that she's running a little lean. With a richer mixture the combustion process is slowed a little.

Please leave major surgery alone for the moment.    :)

Cheers Graham.

Offline Jasonb

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Re: RLE questions!
« Reply #148 on: March 16, 2018, 12:07:04 PM »
You could also make a spacer to move the head away from the cylinder to try things out before chopping the piston, thick gasket may do or a bit of 1/16" sheet metal.

Also if the end of your piston is all solid metal you could bore out the end, if it works then all well and good, if it does not then the recess can be filled back up with metal preferably an aluminium slug as that may help with your balance issues which may be due to a heavy piston. This way you keep all of your rings and won't loose any sealing ability.

Offline Manorfarmdenton

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Re: RLE questions!
« Reply #149 on: March 16, 2018, 12:33:52 PM »
MJM460 - the reason I mentioned .250" was that using a Red Wing piston I have actually increased the crank to piston crown measurement by that amount, and it was also the amount by which Graham suggested in his drawings that relatively higher compression could be achieved.  I was warned though that increasing the compression might make the engine jumpy and more difficult to start.  Both of which it is!

Graham and Jason - yes, I won't do anything in a hurry.  I'm still playing with mixture and timing.  One thing I've noticed is that it still runs but gets quite hot when the timing is advanced beyond TDC.  To far retarded and it still runs but sounds laboured.  The mixture seems to be quite critical - alteration quickly causes the engine to stop.  I'll experiment more over the weekend, and had already wondered about the spacer idea Jason.

John.
John Fearnley