Evening all,

I recently came into a Royal .40 sized engine and already thoughts have turned to dieselizing it. I have vague recollections of the Royal brand of engines but really know nothing much else of them.

Looks like an OS or Magnum or ??? Anyone know, where these a custom made rebranded OS or ?? engine? Does Davis have a diesel head that will fit it? I will probably make my own but it is always nice to have a quick alternative.

cheers, Graham in Embrun near Ottawa Canada.

I was under the impression that the Royal was a fairly close copy of the OS SF engine. I wonder if an SF conversion head will fit?

I wish I could make my own conversion heads. I did buy a modest lathe/mill combination a while back. Maybe I'll give it a try. Now to locate a bunch of low cost, used and good condition engines for the project. <G>

OS SF you say, interesting. I wonder if original parts will fit this Royal then. I see that Tower hobbies still has some replacement parts. My engine is in the mail and uncertain of it's condition. Not an eBay purchase but rather a handful of engines from a friend.

As to finding some low cost engines suitable for conversion, that is just what I have doing to - digging around to find some suitable candidates. I am even planning on making a sparky conversion too. The Royal is the most likely candidate for the diesel and I have a plane for it go into. A McCoy .29 redhead as the possible candidate for the sparky.

Making parts isn't that hard, just takes a bit of planning and trial and error. It sounds like you have everything you need to have a go. I have only a small Taig lathe with milling attachments and it is getting easier with each project as I work my way from simple to the more complex. I hope to one day make my own little diesel from scratch.

cheers, Graham in Embrun near Ottawa Canada.

Used OS .40 & .46 SF engines are selling at reasonable prices on the auction sites. I just bought one a while back. I'm monitoring the auction sites to find another couple of them for Diesel experimentation.

I has Royal 40 and there are 2 difference crankcase, one with whole crankcase or one with 2 part crankcase (fronthouse and crakcase).

Are the Royal with 2 part crankcase older or newer?
Which of them you are talking about Royal 40?[sm=confused.gif]

Jens Eirik

Good points Jen. I don't have the engine in hand yet so I can't answer the question. I have not been able to find much on the internet on the "Royal 40" or 46 size engines other than postings on RCU with very few pictures or else where with very little detail.

I do recall advertisements in the model magazines from years past but don't ever recall making the connection as to the different crankcase styles.

I should have it in a couple of days and will follow up then.

cheers, Graham in Embrun near Ottawa Canada

If your Royal 40 has a removable front end it is a copy of the OS 40 FSR an earlier example and probably the best motor that OS ever made.
dennis

Finally got my hands on that old Royal 40 I mentioned earlier. It is indeed the version with the two part crankcase. The engine is used but not abuse and appears in good condition.

So, from this thread, I am concluding it is a copy of the OS .40 FSR. The engine certainly appears to be well made, the front end is quite substantial when compared to other .40 size engines (ie LA 40 FP 40 etc. So then, the Davis head for the OS 40 FSR should fit nicely and work well then?

Also, will replacement parts for the OS .40 FSR fit this Royal .40 as well?


cheers, Graham in Embrun near Ottawa Canada.

I'm curious to know it the con rod is offset in your Royal 40. I have one like yours with the two piece crankcase. The con rod looks as if its been bent rearward and the top bushing is not in a direct straight line with the lower one when viewed from the side. I bought this new from the local hobby shop so I know it's not crash damage but that doesn't rule out butter fingers in the store! There is clearly a dogleg in the shank between the two bushings but the faces are perpendicular to one another if laid on a straight edge. Neither one appears to have any cant to it. I have not seen a con rod before that was not perfectly straight with the center line axis of the bushings being offset like this. Any help is appreciated as I don't want to spin it up only to have it come apart! Thanks

I haven't done anythin with the engine yet - too many other things to work on.

However, you have peaked my curiosty and I will check this evening when I get home.

cheers, Graham

The davis head will fit your Royal 40 it is listed on his site , same size as the OS 40
Talked on the phone with him yesterday he spent some $$$ on more tooling the head line will be expanding martin

Had a look at my Royal 40. No offset con rod in mine. Not sure what you seeing, sorry.


cheers, Graham

Hey thanks for tearing into yours and checking! I had a Buddy send me a known new rod to compare and the one in my engine is CLEARLY bent! So much for trusting the butter fingered staff at the local hobby shop! Thanks.... Crash King

Two things...

Royal engines were built on the Pacific Rim for Royal Products, Denver, CO, as I recall, . They may have been an early example of "Rim Clones" - not forgetting the Thunder Tiger engines of similar source. The Royal engines may also have differed from their 'inspiration' engines - the OS of the time - in how the carb or venturi was mounted. If I recall, a drawbar locking the drop-in carb or venturi, a la ST, instead of the set-screws usual to the OS...

Second, one of the things I try to check when 'doing' an engine is that the rod is straight. Careful measurement of snug fitting drill rod through the big and small ends of the rod can indicate whether their bearing surfaces are parallel, and if not, can serve as tools to bring them parallel. If the rod is obviously bent, and that compromises working alignment and clearance, I don't have any suggestions other than to try to find a straight rod. (...and check that the bearing surfaces in it ARE parallel...)

The were attractive and nicely done engines. When Royal Products went out (in the early/mid 1980's?), so did all their engines, etc.

If you can straighten, or replace, the suspect rod, you should get good service from yours...

Luck!

Lou, after reading your description of the Royal .40 I think Hobby-Lobby sold a version of it called the BlueBird. The blueBird .46 was the recommended engine for the Sport 500 helicopter H-L sold at the time.

Royal bought their engines from Leo engines the owner is the nephew of the owner of Thunder Tiger. Leo has his own website and makes engines for Megatech as well as others in the car market likt TNT. These are very good engines are indeed copies of both the FSR (2 piece case) and SF series (one piece piece case)of OS. The only problem is in the idle circuit of the carb. The stop screw is to thin and allows the barrel to move when you adjust the idle needle. To deal with the problem make adjustments with the engine not running or when you push in the screw driver you will push the barrel and shut off the engine. The other choice is to make another stop screw. Remember the stop screw rides in the groove in the barrel to cam the the barrel position into the stop position as well as adjuct the idle mixture strength.

By the way these are the type of questions this website was set up to address.

DDD

Bob, will the OS .40 head be a direct fit on the Royal .40, Thanks, Dave

If its the 2 piece case its the M40K if the one piece its the M40SF a different head same price. Over the past thirty years in the 40 class there have been the following models FSR(1), SF(3), FP(1), VF(2), DF(2), LA, SX and the AX (1) and (2) are the same. The following are clones by others Tower 40 (1) Royal (1)(3) Leo (!)(3) Megatech or RJL (3)

DDD