stunthanger.com
Engine basics => Engine set up tips => Topic started by: Charles Hofacker on February 14, 2021, 06:01:46 AM
-
Hi,
I have an OPS engine that has never been run. I want to break it in properly. What is the best procedure for breaking this engine in?
Thanks
-
Hi,
I have an OPS engine that has never been run. I want to break it in properly. What is the best procedure for breaking this engine in?
Thanks
We need to know more than just "It's an OPS engine." Ringed engine? ABC? Iron piston and liner? A basic rule I was taught is you break in any engine under a normal load at a normal operating temperature. Use the same fuel you would when you put it too use. Use a prop about an inch shorter diameter and an inch or so less pitch on a test stand. Modern metallurgy will just require short runs with cooling in between. Older technology will take longer runs to seat a ring or make a piston fit better. Keep the RPMS up at close to normal speed, just not screaming lean. Again, it depends on the engine.
Type at you later,
Dan McEntee
-
I don't know much about it and nothing about its metallurgy. I don't even know its actual age. I've had it for a long time. It does not have piston rings. It is a rear exhaust aircraft motor as opposed to boat or car. There are no markings on it other than the OPS in the casting on the side. I had believed it to be a .21 cu.in but I measured the displacement several times and I believe that it is much closer to .19 cu.in. By my measurements it is .1875 cu.in. I have never had any documentation on it. It had an R/C throttle on it which I have replaced with a fixed venturi and needle valve. If my memory serves me it may have been advertised as a helicopter engine. I've poked around with Google and found nothing helpful.
-
At that displacement it could still be a car engine. That is the only thing that makes sense to me with the R/C carb and rear exhaust. I think I remember having seen adds for OPS car engines back when I worked a lot at the hobby shop. They are a known high performance engine manufacturer. If it was a heli engine it would have a big head and cylinder fins for extra cooling. If it was a boat engine it would have water jacket cooling. At this point, you got me!
Type at you later,
Dan McEntee
-
Hi,
I have an OPS engine that has never been run. I want to break it in properly. What is the best procedure for breaking this engine in?
Thanks
Hi.
At the web address below you can find the complete catalog of OPS engines relating to the 90s.
In the file "Consigli per il tuo OPS" you can find everything that interests you and by searching among the other pages of the catalog you will probably be able to identify your engine.
https://www.mantuamodel.co.uk/products/ops-engines/spare-parts
I hope this helps.
Massimo
-
Hi.
At the web address below you can find the complete catalog of OPS engines relating to the 90s.
In the file "Consigli per il tuo OPS" you can find everything that interests you and by searching among the other pages of the catalog you will probably be able to identify your engine.
https://www.mantuamodel.co.uk/products/ops-engines/spare-parts
I hope this helps.
Massimo
Thanks! This was a huge help. Now I know the piston/cylinder metallurgy to be ABC. The engine matches the 2.5-SPA-RCA. Rear exhaust, front intake, throttle carburetor.
With this new information is it safe to assume short runs with cooling in between is the way to go for break in?
-
Thanks! This was a huge help. Now I know the piston/cylinder metallurgy to be ABC. The engine matches the 2.5-SPA-RCA. Rear exhaust, front intake, throttle carburetor.
With this new information is it safe to assume short runs with cooling in between is the way to go for break in?
Yeah, that is just what was needed! and yes, short runs with cooling in between or what they call heat cycling. For that displacement a 9-4 or so should do OK. Run it where it is cleanly up near the 4-2 break for a minute or two, then pinch the fuel line until it quits. Most ABC engine require anywhere from 10 to 20 or so such runs. You will feel a slight difference in how it flips over. If it is hard to start at first, but gets better as you go along and then gets easy, that's a good sign you are there.
Type at you later,
Dan McEntee
-
The engine matches the 2.5-SPA-RCA. Rear exhaust, front intake, throttle carburetor.
There's an engine test of the 2.5 Speed at http://sceptreflight.com/Model%20Engine%20Tests/OPS%20Speed%202.5.html
-
Ok it turns out that the engine is a 3.5 (.21cc). I was thinking about using it on a duration free flight.
-
Ok it turns out that the engine is a 3.5cc (.21cu.inches). I was thinking about using it on a duration free flight.
Seems like a good match...something around 600 sq. inches would go good. Could scale up/down anything you like the looks of. Depends on whether you want a locked-down, auto-rudder or full VIT design. y1 Steve