where on the back plate do you tap it for a perry pump

See attached picture. Regards

Vicente Bortone

Tapping the Backplate: Although there are folks who recommend drilling through the upper left backplate mounting screw hole with a 1/16" drill, I will not recommend that method, as for me, it leaves too great a risk of metal shavings (small though they may be) being left in the counterweight and bearing/lower conrod bushing area of the motor. Not good. Rather, I suggest that one simply use a DuBro 6-32 pressure tap and drill the backplate after it is removed from the motor (any place where there will be room to install the pressure fitting). Then, simply install the pressure fitting using some permanent-type Loctite, the washer that comes with the fitting, and make it snug. After the loctite cures a bit, use a dremel grinder wheel (or cutoff wheel) to remove the excess threads protruding on the inside surface of the backplate. DO NOT FORGET TO DO THIS!!!! Wipe everything off, and reinstall the backplate. Done. No risk of metal floating around in the motor. This is from:

http://www.rcaerobats.net/OS160_Setup.htm

where on the back plate can you install the fitting, the wall is so thin that the pressure fitting witll protrude and hit the connecting rod

And if you cut the excessive threads is there enought thread left to hold it?

Guaranteed to work. Grind off the excess that protrudes. Plenty of thread. Use permanent loctite when installing, if you're concerned. Have done probably half a dozen or more - all work fine, no problems.

I am one of the folks who drills the crankcase for a pressure tap. Confession is good for the soul so they say!

Both the OS 1.40 EFI and the OS 1.60 FI use a pressure nipple in the top left bolt hole instead of the bolt. (Looking from the rear of the engine).

To get pressure from the crankcase to the bolt hole, a 1/16" drill is needed to complete the bolt hole all of the way into the crankshaft chamber. The replacement bolt/nipple is an easy to obtain OS part and is approx $6.00.

I prefer to take the engine apart before I actually drill the hole. I have owned a total of 14 OS 1.60's. I have done this pressure-tap conversion on most of them, [Add another six for friends or anyone who needs it done] Please forgive me for mentioning the "credentials" but I wanted it to be clear that these are my experiences and not just vicarious observations.

The OS crankcase of the FX's and the RX, in question, have extra metal already in the casting. (They (OS) use the same blanks for the fuel-injector engines and the regular engines).

Care needs to be taken to not damage the existing threads. What I do is use a copper/brass-tube-sleeve over the 1/16" drill bit. This helps center the drill bit in the bolt hole and protects the threads.

I usually do the drilling as part of the process of changing the main bearing. I do not run a big OS with the supplied bearings. I change them over to stainless-steel as a matter of course.

You do not have to "crank" the OS pressure-tap-bolt down hard because the backplate uses a large "O"ring seal. "Snug" will do the job.

Hope this helps?

Of course, you can just go out and buy a milling machine and/or a lathe and a $150.00 OS pump and risk it all. See below

Regards,

Eric.

P.S. I have tried both the Perry and the Cline (also Iron Bay) with these pressure taps. The Perry's always worked intitially but became erratic after several hundred runs. The Cline and the Iron Bay regulators never varied from the get go!.

P.P.S. I have tried the tap-in-the-backplate, but the threads are too coarse for an aluminum wall that thin. If you do go this route you would be well advised to use JB Weld to keep it in place.

ok thanks just I dont want to ruin a back plate and have to get another one where can you get the pressure fitting for the OS

Tower Hobbies. Look under parts for the FI version of the 1.60. I agree with Eric. Drilling the cracnkcase is a lot easier than messing with the backplate. If you don't get the threads absolutely flush on the backplate, the con rod WILL hit it. I just converted a friends 1.60 who had this exact issue.

Here's how you drill without getting junk in the crankcase:

Take the backplate off.
Stuff a paper towel soaked with oil into the crankcase, in the area of where the drill will come thru.
Use a 1/16" bit in a drill. Turn the engine so that the crankshaft is vertical, and drill the hole from the bottom so the shavings fall out.
Keep the engine vertical, and keeping the paper towel stuff against the new hole, spray the threads out from the bottom with some automotive brake cleaner.
Turn the engine upright and carefully remove the towel. Most of the shavings will have fallen out the bottom, and the oil on the towel collects the rest.

I've used the Perry pumps for two years without an issue. Had zero luck with the regulators.

Jon Lowe

What is the prefered glow plug for this engine. only getting about 3 flights out of an OS #3 before it blows

OS # 8 or Tower Plugs.... last a LONG time if not too lean.

I've used both the OS #8 and the F successfully. I run the F now. They last forever.

The first year I ran the 1.60, I had a problem with blowing the seals out of the plugs. Finally traced it to doing warm starts of the engine using a starter. Now I simply backflip the engine using the spinner. Starts easier than with a starter, and zero blown selas since. My engine ALWAYS starts on the first or second backflip. I've had 3 of them, all act the same way.

Jon Lowe

It's not nice to NOT share little tidbits like that, Jon..... SHAME on you!!!!!
It must have been great to learn why the seals WERE getting blown.... good detective work.

Agreed.
The only thing, they keep going so long, it's worth checking the top and bottom revs from time to time, as the top end drops off a bit, and it won't idle quite so slowly, before the plug actually fails---

Hey, I thought I told you at the time! Maybe you're getting forgetful, or maybe it's me. I can't remember!

Jon

Hi Jon,

How does this back flip start work? I always start by hand but never had an engine of this size. Only recently got the 160 and are still building the plane.

Regards
Attie

You grab the spinner, and flip it clockwise against compression, with the idle trim set at normal idle speed. It bounces back when the mixture fires and starts. Occasionally, it will start and run backwards. If it does, lower the idle trim gradually until the engine almost stops, and most of the time it will kick slightly and reverse itself and start running in the right direction.

Jon

What fuel you guys use for OS160?
MY LHS recommend me to use SIG FAI fuel with 20% oil and "NO" nitro. They say it is better for large 2 stroke engine like OS160...?
I am not quite sure..

Thanks

Mike Shih

I run 15% Cool Power and 15% Omega (both from Morgan fuels) interchangeably. I like getting a little castor in it occasionally with the Omega. I can't imagine running on 0%. You LHS doesn't have a clue about OS 1.60s. Might be true for Mokis, but not OS.

Jon Lowe

Your LHS is clueless. Use 15% nitro with some castor oil.

The advice from you LHS is completely wrong. He must be thinking of a Moki or something. Even there, you want at least 5% nitro, up to 10% at most.

For the OS 1.60, 15% nitro is what you want to fly with. You can go up to 20% if you want to (trips to Muncie in July for example), but it's really not needed. Oil content around 18 to 19% is fine, can be all synthetic or a castor synthetic blend. Lot's of choices here for fuel, the OS 1.60 is not a fussy engine by any stretch, but 15% nitro makes it sing. Use an OS type F plug for the best idle and midrange transition.

Thanks so ... much !! Great help !
I will go exchange the fuel.

Mike shih

Yeah, I do the "drill through the upper bolt hole" too. I do this when the motor is brand new and I'm changing the bearings. That's the best time to do that too. I use the Boca stainless steel bearings with seals on both sides - front and rear. No danger of metal shavings when you drill for the tap because you have the motor completely apart. The nice part about using the upper bolt hole is that you can always go back to a non-pressurized system by removing the tap and re-installing the original bolt. The 160 is a super friendly motor. Electric start the first time at the field. Once the pump is primed and she's warm, back flip and go. Like an old Harley - starts on the 2nd or 3rd kick.

John Pavlick