which oil to use to lube a hit-n-miss

[bmuss51]

i just finished building a nh hit-n-miss engine which is my first model engine.and at assembly time i lubed all part liberally. but even with the oilers all the way open things are getting sticky. and as of this time i only used 10-30 motor oil and the Cly. doesn't seem to be getting enough lube, but the other bearing with cup oilers are fine.
there is a hole in the side of the piston which allows oil to drop through at the bottom of the stroke to lube the wrist pin assembly which seems to be working fine, but the Cly. gets real dry when i run the motor. and there is about .002" between the Cly. and the piston which is starting to show signs of wear and it only has about 10 min run time in short runs like maybe 6-10 rev. which i am getting it to run better fooling around with the timing and carb settings.
so which oil should i use or is there something else i should be looking for?

 

[hitnmiss]

Bob Shores recommended WD-40 mixed in the fuel.

I made up a 16oz fuel container of break in mix with about 25% wd-40/75% coleman fuel. The plan was to switch to 10% wd after break in.

That was about 4 years ago and I've got about 4 oz left!

Nice mix cause inside the exhaust smell isn't too bad.

 

[bmuss51]

i forgot to mention that i do have a mixture of wd-40 added to the coleman fuel of 10%.

 

[Lew Hartswick]

WD 40 is not a lubricant.
...lew...

 

[GrahamC]

WD 40 is not a lubricant.
...lew...

but it does contain approximately 30% by volume of a "light petroleum oil" the remainder being primarily Stoddard Solvent. In effect and in simple terms approximately 2/3 kerosene and 1/3 light weight oil.

I have used WD40 from time to time to mix fuel for small 2 cycle model diesel (actually compression ignition) engines.

cheers, Graham in Ottawa Canada

 

[bearcar1]

This might very well turn out to be a very stupid thing to ask but coming from a heathen that knows very little about small model IC engines (but I'm willing to learn), could 2-cycle engine oil such as used in lawn mowers and weedwacker fuel be used or is it too viscous for this application? I'm sure that the smell would be one factor to deal with if it could.

BC1

 

[GrahamC]

This might very well turn out to be a very stupid thing to ask but coming from a heathen that knows very little about small model IC engines (but I'm willing to learn), could 2-cycle engine oil such as used in lawn mowers and weed wackers be used or is it too viscous for this application? I'm sure that the smell would be one factor to deal with if it could.

BC1

I really don't know how to answer your question and as no one else has spoken up I thought I should post a few comments.

I don't have any experience with the hit and miss type IC engines that was mentioned in the first post of this thread but I do recognize the name Bob Shore and his relationship to the subject. If that is what he recommends for these types of engines then it is probably something you can count on.

There are many types of small IC engines besides the hit and miss types. The ones I typically mess around run at much higher speeds and usually on alcohol. Castor oil is often used in these high performance engines along with some synthetic oil. Neither synthetic or castor oil would be suitable for the hit and miss or other types of open frame engines - castor oil will not go into solution in a gasoline/kerosene fuel. The typical "model airplane" engine needs a fuel which lubricates everything from the crankshaft through the big and little end of the connecting rod and the piston/cylinder - the ends of the connecting rod being of particular importance. Thus the fuel tends to contain a lot of lubricated, typically in the range of 20 to as much as 30 percent. Whether the engine has ball bearings and if the piston/cylinder is steel/iron or ABC (aluminum piston, chrome plated brass cylinder) will influence how much lubricant is in the fuel. The requirement for lubricant in the fuel for these hit and miss and open frame IC engines is very different.

Typical motor oils have ash, sulfur and phosphorus among other additives are probably of little or no use in these lower speed and pressure engines.

When I want a "clean" oil without a lot of additivies I turn to air tool oil or sewing machine oil. When I assemble and/or store my small high performance I use automatic transmission fluid as an assembly and storage lube.

Lubricants is a very big topic and there is no simple answer without knowing the application and conditions under which it will be used. I am no expert and have forgotten more on the subject than I can remember. Surely someone with more experience on these hit and miss and open frame IC engines will speak up and add more to this discussion.

cheers, Graham in Ottawa Canada

 

[bmuss51]

i asked locally the same ? as above to 2 diff. guys that run full size hit-n-miss. with the same answer from both. being, that back in the day or era of the full size. the only oil that was readily avail. was standard 30w oil. and it worked fine on them for all the yrs they have been around. so i tried the 30w oil which gave me very good results compaired to the 10-30w i was using. and it seems the motor is running more loosly and it has more power. but boy does that oil come out black. which i was told that is from combustion and is normal for this style of engine. so now that problem is solved for the time being. i'm on to the next hiccup i have which is getting the gov. to work better so the engine will run slower. and i believe it's just a matter of tinkering and fine tuning.

 

[hitnmiss]

WD 40 is not a lubricant.
...lew...

Don't tell my engine that's been "not lubricated" with it for 4+ years!

 

[itowbig]

Don't tell my engine that's been "not lubricated" with it for 4+ years!

ok we wont tell your engine. but to be on the safe side better get some ear plugs for that engine :big: Rof} Thm:

just joking around fellers i was bored.