Member postings for KEITH BEAUMONT

No E Mail in any of my boxes.

Keith

Hans,

Glad you are now OK for Drawings of the Viper. I have been on holiday so was unable to offer my set.

Sheet 2 , Crankshaft, I pressed in the pin before doing any lightening. I usally hold the shaft horizontaly in the chuck and use a radius cutter in the mill. Take horizontal cuts either side of pin and you then have a nice radius in the corner.

Sheet 4, cylinder. The small difference between # 33 and 3mm will not effect any performance, probably improve it. Another version of the cylinder has much larger transfer holes, The important thing is to ensure the top of the hole is correct in relation to the exhaust. I used a 3mm solid carbide slot drill .(see previous page) One tip is to use a sacrificial plug in the cylinder to prevent snatch on breakthrough.

If you have any other queries just ask. Please make sure you give the necessary clearances to the Ball races.

Keith.

Dave Wooton,

You probably saw that add in a thread of mine a few years ago. Photo is in my Album under the Chennery Vee-Twin photos. Top row 3 rd from right.

Keith .

Tug,

Re- reading the Mills advert, it claims the "Mills Transfer System " is Patented, so perhaps this is why others did not use it. It might have been a bluff of course. If Michael ,our Patent expert is out there, perhaps he will know more of it?

Keith

Tug,

I think at the time most people believed it. I made Ron Chernichs version a few years ago and did try out the test, as suggested and there was a deffinate look of fine atomisation.I did not reverse the piston to see if there was a difference tho. Why were so many with the piston wrong way round? As a teenager, I would take one to work and start it by holding it in one hand and flicking with the other, to demonstrate it's easy starting !

Keith.

Hi Ramon,

Yes I have the Mills advert series. Attached is the one I mentioned.

Keith

Roy,

I am interested to know why you would want the piston to have a flat top.? With the 4 inlets angled up at 25 degrees,the piston top is the same angle,the purpose of which is to make sure that maximum fuel is forced to the top of the cylinder. The Mills 1.3 engine was advertised as having a notch in the piston top, adjacent to the inlet. to atomise the incoming fuel. This was claimed to be the reason for their famed easy starting.

Also, if you cut the top off the Vipers piston,as drawn, you end up with a big hole in it, as the inside shape follows the outside.

Keith.

Hi Tug,

Re-capping on this engine information made me realise that I have two different sets of drawings for it,all with the same date,other than Sheet 8 the revised Cylinder/Head drawing, which is dated 18/12/2011, the others all being dated14/12.2011or 15/12/2011 I had been interested in this engine for a few years and had previously printed a set and forgot about it... The Crankshaft , Sheet 2 has two designs. One has a plain circular web, with no relief for bearing or con-rod.. The other is radialy lightened,with relief for con-rod,but not for the bearing.Same date, 15/12/2011. Sheet 4, Cylinder, has different size for sliiting saw to be used for Exhaust slots. One is 3/16", one is 3/32". This one does have a note mentioning change of saw and lowering the port and flange top by 0.022"to allow for the change of slitting saw. Both have same date. this time 14/12/2011. Sheet 3, Backplate,has different centre measurements for the Inlet, differing by 0.015" vertical and 0.055" horizontal, which will alter the timing. 15/12/2011 for both. Sheet 5 Contra piston has a completely different shape.

It therefore looks like two different engines can be made from what looks like the same Drawings. Three if you count the the revised sheet six, withe the integral fins and larger modified shape ,inlet ports. I find it odd that Eric Offen, who produceed the drawings using the same dates, has not clearly stated that two versions exist

It would be interesting to hear what versions have been made. Which mix did you use in the one you made?

Keith.

John,

When you mentioned that you were part of the previous long discussion, I decided to read it all again, but did not think a deffinate result came of it.. My simple thought about fitting ball races is that the outside and the inside diameters need restraining for the shaft to rotate properly I use the same system as Tug Wilson with the first bearing. Put the bearing on the crankshaft first, heat the crankcase and drop the shaft and bearing into the case. I have previously made honed test pieces to determine the restrained fit for the inner diameter. This is 0.0005" larger diameter than the shaft, so I hone the shaft to give this restraint and I find it works for me. My cylinder is EN1A with CI piston,as I used the original design drawings. Dated15/12 /15. I also made the crank web the full thickness 0.160" aand lightened it by removing two scallops either side of the pressed in crank pin.

Roy,

As the front bearing does most of the work,i have always thought that having a smaller front bearing was more to do with trying to be lighter,rather than for some technical reason.

14,400 RPM sounds impressive to me and I will be quite happy to avhieve similar. At the moment I am still having short , mostly rich runs and am just hovering around 10,000 RPM. When I pinch of the fuel tube to stop it, I get a burst of high revs, so we are not there yet. I will come back with more progress later.

The fastest engine in my collection engine is one I was given and no one has been able to identify. It is a Glow, about 4cc.beautifly made with a real deflector on piston head, with matching space in cylinder head. It will rev at 16,000 with a 10x4" prop, but has only a plain Ali bearing in the case. The front housing is Ali too but has been bushed with another type of Ali. Can be seen in my Album. in the Vee twin photos. Has black, steel integral fins. Probably a prototype from somewhere.

Keith.

John,

Most of the mods I carried out are mentioned in the original post, other than I machined 0.025" clearance for the inner bearings to clear the front housing and I put same dimention clearance on the con rod face to crankshaft.

Cooling in a tethered car is not as efficient as a prop in front,so perhaps it did heat up somewhat. How did you correct it?

Keith.

Neil,

The mention of the engine runniing hot at that stage was not mentioned as a problem, more as a characteristic of this particular engine. when compared to others. With four angled inlets,it is clearly getting a good charge of fuel per bang. At no time is it over compressed. Now it has had several more minutes of run- in, it is running slightly more cool.

I would need a lot of persueding that leaving one rubber seal on the front bearing has any effect on performance whatoever. compared to it s use in keeping any muck out of the bearing..

Keith

Edited By KEITH BEAUMONT on 02/09/2023 20:10:14

Hi,

The thought that it might be something to do with harmonics had occured to me.Whether it is just a theory, or has been known to have a practical result, would be interesting to know. When I have read old AEROMODELLER magazine engine tests by Peter Chinn, of engines with double ball race crankshafts, the ball count of each race was mentioned, rather than the size and I often wondered why, as the reason was not explained, so perhaps it was a well known fact in those days.

Keith

Thanks for tidying up the title, Mods.

Keith

Hi Tug,

Thanks for your appreciative remarks. It is always good to hear from you. Liner is not hardened. I am aware of the possibility of galling,but I gave both the liner and contra a good coating of copper grease when assembling. I have used EN1A for contra pistons on two smaller engines,using copper grease, and they have not seized. Yet.! Machining a stick of 01. 25"diameter cast iron down to less than 0.5" diameter always seems such a waste.

I have not heard that it is not good to use identical bearings on a cranshaft, It sounds an interesting point. Surely, on a muti bearing shaft they would keep to the same size. Perhaps someone will come on and explain the technical reason.

Thanks again.

Keith

Mods. What has happened to the FOR SALE department?

Keith

Hi Emgee,

I have removed all but the front seal and the front housing stays reasonable. The heat is in the head, but is improving.

Sorry about the few typos. I was being called to lunch and was more concerned that the photos were in the right order,due to the need to put them in reverse . What happened to the title I have no idea. It looked OK when I pressed the button.

Is it possible for a kind Mod to put that right for me?

Keith.

These are photos of mylatest I/C engine build, the 2.5cc, Rear Disc induction, NALON VIPER, diesel. I had notrealised until I had assembled the engine that it also has sub piston induction. It was an interesting project and mindful of the discussion on this forum a few years ago,about omissions on the drawings regarding lack of clearance for the ball races to work correctly, I re- drew the front bearing housing and the crankshaft to accomodate the necessary clearances, changed the crankshaft to have both ball race bearings with the same 3/8" diameter internal bore and moved the step down to 1/4" diameter to be 0.025" in front of the seated ball race,allowing the Prop Driver collet to fit against this and not the bearing. Also,changing to a conventional male thread for the Spinner. The Cylinder to Crankcase flange is circular as drawn and therefore minimal sealing area. This I changed to be the same shape and size as the crankcase. This not only increases the sealing area, but also gives accurate re-location of the cylinder/piston relationship for any strip down after the engine has been run in well.

The 4 inlet ports in the cylinder are angled upwards at 25 degrees. No correct information is on the drawing to make sure the exit holes are in the right place and in relation to the 4 exhaust slits. This provided some brain searching regarding hoe to carry out this operation without making a mess of it. I finally decided to ghech 10 time and cut once, by making a dummy cylinder in Ali Slitting the exhausts in the mill and drilling using a solid carbide slot drill in my Dremel, mounted at 25 degrees on my lathe, with cylinder in the indexed chuck. I then cut this cylinder down through its vertical centre, to allow me to accurately measure the relative positions of the drillings inside the cylinder. Fortunately,they wer all spot on, so I repeated the drilling process with the steel cylinder. All parts went togethe without problems.

Set up on the test stand with a wooden 9x6" propeller,it started faily easily and was given two x 4 minute rich runs ,with cool down between. No gaskets, no leaks. The third run I over primed and had a back fire or two. Once it had started it would not respond to any adjustments so I stopped it. Compression was not good, so took head and cylinder off to find that the compression screw had punched through the cast iron piston ! I assume that by backing off the compression screw a full turn the contra piston was then slammed onto the screw at the next backfire,causing the cast iron to fail. It is my practice to put a small 45 degree bevel on the end of the compression screw thread, as I have found that lft square the end thread can deform and prevent it being able to be removed from the head if needed.

I decided to make the new one in EN1A. Thisis fitted and two more 4 minute runs have taken place since with no problems. I noticed the wood prop had a damaged edge where it had hit my starting stick when it backfired, so these later runsare with an APC nylon 10x4"prop. When I have allowed it to run slightly leaner for a minute it is hovering around 8000 RPM andthe photo of it running is at that speed. I am noticing that this engine is running hotter than other diesels Ihave made. The oil from the exhausts is brown and has that burnt Castor smell. This will possibly diminish as the engine frees up after further running. It will be interesting to see how far I can take this engine,remembering that it was designed as a high performance sport engine of its time.

Keith.

Hi Geoff, It is all looking good ,so you are not far off hearing its first cry!

Keith

Hi Geoff, It really depends on whether you are going to put the engine in a model that will fly. If so, it might be a good idea to be able to lock the compression, but if you are just going to run it on a test stand, I personally would not bother. You will be adjusting compression as you enjoy hearing it run.

Keith.

Jason, once again you have the answer, but that is an engine I have not tackled, yet!

Keith