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P.M. Research's


The Engine is not shown on P.M.'s web site but is available at this date. The introductory price I believe is $159.00 and comes only in the fully machined version at this time.

When you live in upstate New York you look forward to something to break up the Winter blues. In my case that something happens to be "Cabin Fever" a great model engineering show in York, Pa. I was looking forward to the show as I had ordered some castings from Pearl Engine Company for a make-up water pump and to look at their new hand pump. After getting my castings, hand pump included. I visited P.M.Research's booth to see them and tell them about my construction article on their Dynamo. I instantly spotted the newest engine a 90-degree fully machined marine engine with reversing and is also throttlable. This all works on a single lever that moves 45 degrees in both directions. The display engine seemed to have excellent throttle response and seemed very powerful for the size. I think that this engine would be suitable for boats and launches of over 48 inches long. P.M. is calling it a marine engine but I personably think it will be used for many projects requiring a self-starting steam engine. The arm is setup so a standard R/C servo will hook to it very easy using a simple r/c quick link. One servo will give you both forward and reverse as well as speed control. After reading the instructions it appears it will go together in a few hours. Time will tell as I plan to build mine first thing tomorrow morning. Now for a few pictures and details of the new No. 8 engine.


Shown in the picture on the left is the main base casting with the 2 frames for the cylinders as well as the tubes supplied as pre-assembled part. The brass cylinder covers are in the upper part of the picture. The 2 others are the anodized extruded aluminum cylinders. The anodizing gives a much harder surface for wear. The inside is also done for piston wear. It appears P.M. did not try and cut any corners and has a high quality kit that will last a lifetime.


There are two bags of parts including all the necessary nuts, bolts and screws. It appears to be a very complete kit. The only item I see that a person might need would be a small tube of locktite to keep some  of the screws from vibrating loose. P.M. mentions where they suggest using it in their instructions More on assembling it later on.




On the left is an exploded view of the engine from the assembly instructions. The bottom picture shows the cylinder assembly

Now for the FUN PART!






I decided that I would just polish up the machined parts and paint the castings at a later date. I pretty much followed the instructions except for a couple of places. The bushings were pressed into the case and the control valve was installed. The tubes on the block were polished along with the control valve and the back plate that holds it in place.


I had a reamer handy so I rebored the bushings after they were pressed into the main block casting. I don't think this would have been necessary as it didn't feel like the reamer cut off much material. The crank and shaft were then installed




The two cylinders were prepared for installation per the instructions. It was a little confusing at this point because no mention of the piston sub-assembly was indicated. I have built their #2A which uses the same type of construction. When I installed the piston on the rod I strongly suggest using locktite to ensure the piston stays in place on the rod. The cylinder pivot point was also locktited into the extruded cylinder.


The assembly was then installed and fastened in place as indicated on the plans. The adjusting rod between the two tubes was adjusted to make the cylinder square with the crank and also to give a little clearance so the rod end clears the crank. This system seems to work well as in no time it fit well and turned over stiff but with NO binding at all



The other cylinder was then installed and adjusted like the first one. The engine turned over a bit on the stiff side so I decided to run it in a bit on my combo lathe -mill. I simply held it in place with my chuck tightened around the crank shaft. The mill uses belt drive so I loosened the belts so the spindle would slip easy if something bound up. I held it from turning with my fingers with my other hand on the off switch button. Be VERY careful if you do anything like this and make sure it is chucked in only by an 1/8". That way it will simply come out of the chuck if something binds or goes wrong.  I kept the speed down to 120 RPM and ran it for about a half hour. After that it had loosened up considerably but was still a little on the tight side.

I then took the engine apart and cleaned up everything with some mineral sprits. I then reassembled the engine and put the brass lagging and top heads on. My engine is now complete and ready to go! Total time was a little more than I anticipated. It was just a little over 4 hours but that included time for polishing and some run-in time on the lathe.




Its now back together and ready to try. I think I will give it some more break-in time on the mill before trying it on air. It seems to still be tight but with no binding anywhere. After an hour of running on the mill it was much better. The engine would either pump air or suck a vacuum depending on the position of the control valve. With the control valve in the off position there was noticeable binding as the air had no place to go. I did not let it run in the off position but just switched from forward to reverse.


Shown in this picture is a good view of the control valve and the steam inlet located just behind the control valve arm. This picture was taken just before I ran it on the lathe. It still needs two lock nuts on the pivot shafts. The 3/16" crank is a standard size for drive dogs available through Dumas Products as well as others. It has a flat machined on it so the drive dog will not slip.



All ready to try on air. Notice the oil is still running on the dark side indicating to me its still breaking in. P.M. doesn't give the size of the steam inlet and outlet. It might be a 1/8" model pipe size as 3/16-40 looks to be too large. Hopefully PM will include the size and also something on piston assembly in future instructions. I will check that in the next day or so and make an air adaptor to fit.



Watch for Testing & Performance

Coming Soon!

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