End Play on drum Rotor

[Jerry Muro]

I am looking for some feed back if any one has any on a OPS drum rotor 45. It seems as though I have some end play and was wondering if this is normal or excessive? The motor is fairly new not even a gallon ran thru it. I am running an OS 4E carb o it along with a OS 3rd channel with the neddle with groove. At this time I have 25 thousand clearness does this sound right or to much? I appreciate all responces. Jerry

 

[outboardman10]

I am also running a OPS 45 Drum engine, and when I set the drum up to the rotor, I use a piece of white printer paper with a slit cut into it to slide around the pin into the drum. The piece of paper is (if I remember correctly about .008 of an inch). I am no expert on engines, but this has seamed to atleast run fairly well for me. There is also no slop in my rotor after about 3 or 4 gallons of fuel fun through it.

If anyone else can confirm what they run, I am definatly also open to the tips!

 

[tnrcboatracer]

If you used a piece of paper to set the clearance, you have a disc rotor engine. Drum rotors typically do not have their clearance set, other than by machining some parts.

 

[CMBrunner]

I am looking for some feed back if any one has any on a OPS drum rotor 45. It seems as though I have some end play and was wondering if this is normal or excessive? The motor is fairly new not even a gallon ran thru it. I am running an OS 4E carb o it along with a OS 3rd channel with the neddle with groove. At this time I have 25 thousand clearness does this sound right or to much? I appreciate all responces. Jerry

I am a little confused by what you mean "end play"

If you are referring to the fore and aft movement of the drum within the housing, then

I think you might consider taking the gasket out and re-checking. You will want "some"

clearance, but you don't want it tight.

If you are referring to .025" clearance around the drum - then you might really consider

changing parts - or having the drum housing bushed by a machinist.

And, while the subject is "on the table"....I would like to ask people what issues (if any) they

have run across with the steel drum in the un-bushed alum. housing? I was told not to bother

running the motor without having the housing bushed because it would eventually cause problems.

 

[David Neelman]

Mine was bushed by a member of my club who is one of the best machinists anywhere, who, to my knowledge, matched the clearance of the drum to the bronze bushing, to the specs he measured of the drum to the unbushed housing when motor came out of box.

I have been running this for going on my 5th season now, with no wear at all.....I just did a tear down and inspected it.

I also, did research when new, and found that many many folks who tried engines through the years w/o a bushing.......eventually, lost the seal, and the motor would not run correctly or hold a setting. It is pretty much assumed that a bushing is absolutly necessary.

 

[David Neelman]

As far as end play.....my older disk rotor OPS 45s had some, due to the design, but the drum version has very little. I have never had a problem, and like someone else mentioned...there is no adjustment, sans machining the parts.

 

[Jerry Muro]

I would like to know what the end play is as I have 25 thousand. When you say very little what does this mean?? Mine is bronze bushed as well just curious as to what is normal and what is not. From what I understand 25 to 30 thousand is normal for a drum.

 

[tnrcboatracer]

When you say 20 thousand, do you mean 0.020"? That sounds lke too much. How are you measuring this? The only way I know to measure end play on a drum is to remove the rod and sleeve from the engine, and measure the gap or movement between the drum and crank pin once the back plate is bolted back on.

 

[David Neelman]

To be honest.....I have not payed much attention to it, as, fortunately, the engine has not been out of the boat much. I've also never had a reason to check it. With the old disk motor, you could grab the flywheel and feel a significant click for and aft. With this drum version, it's pretty darn tight. Now I'm not sure if that's directly related to end play or not, but, I have found that difference. I know this doesn't help answer your question much, sorry, but if there's anyway we can compare "feel" this weekend at the race, without taking both motors apart....we can do so. I wish this came up a couple of weeks ago, as I could have checked it out while I had it apart to put a fresh set of bearings in.