OPS Marine Engines

[David Bryant]

Thanks everyone for all your good info.

Appreciate the images of the drum valve assembly, surprised OPS would go to the effort to produce a drum-valve and not employ a bushing? And a rotor diameter that small? Unbelieveable. This is enough of a show-stopper for me.

I would have considered having the OPS drum-valve backplate modified and fitted with a custom bushing (as was very commonly done on past Rossi .67/.80 drum-valve backplates), but with the small limited intake bore inside diameter of the drum it would be a waste of time. And I would rather not screw-around using K&B backplate assembly.

I still run a few OPS .45 disc-rotor engines (from 1989) in my current mono's, they run beautifully and fast, and reliable. I've been mostly happy with them. Consequently when I saw that the current versions are employing a new drum-valve design I considered using them for new boats. However I will now consider other current models- ie. CMB .45VAC, A/A .45, or possibly Picco 45R.

 

[Scott Miller]

Hello all, thanks for all the interesting information regarding OPS marine engines. I currently have 2 OPS .67 that I plan to run next season in 1/8 scale hydros (circus circus). My latest aquisition is a Circus Circus that came with a OPS .67 (see attached pic). As you may have noticed there is a K&B carb on this motor. Last night I took the motor apart and the drum vale appears to be stock, the K&B carb neck wobbles a little bit in the valve base but tighends up with the draw bar. Should this have a sleave added to tighen up the carb? Or should I look for the stock OPS carb (slider)? Anyone have any experience with this?

 

[David Bryant]

that came with a OPS .67 (see attached pic). As you may have noticed there is a K&B carb on this motor. Last night I took the motor apart and the drum vale appears to be stock, the K&B carb neck wobbles a little bit in the valve base but tighends up with the draw bar. Should this have a sleave added to tighen up the carb? Or should I look for the stock OPS carb (slider)? Anyone have any experience with this?

I would prefer to use a sleeve between the K&B carb neck and the backplate carb mounting bore, provides a more snug (proper) fit. Otherwise I would just use the OPS carb that was designed to fit the backplate mounting hole.

 

[Tom Foley]

The carb must fit very tight and i would reccomend using JB weld or similar near the last bit of the carb to go in the bore or it may fall out or leak on you . RED loctite the drawbar nut as well .

 

[David Bryant]

CMB and AA are the best readily available right now with major upgrades to the larger transfer ports , wide exhaust ports and more open intake entry into the crankcase

yeah CMB, AA, (existing) MAC's, and Picco seem to be the more competitive current engines out there.
Seems I notice a significant number of CMB owners selling their (newer) motors on this site?

What is best performing .45 out there currently (an open question of course)? CMB .45VAC? Picco .45R? AA .45? MAC .45? Or are they all somewhat close? Are the differences more related to stock carburetor configuration?

 

[David Bryant]

Was curious, were these Aeromarine "roller" bearings (for OPS 45 Marine) intended to be used with an after-market front crankshaft housing?

 

[brad nichols]

I still run OPS and old PICCO's that are not the most competitive as the new generation but they are reliable. Big thing is you have to finish!! I have 1 OPS 67 and 2 80's plus I have aquired some OPS 90's. I have to see how the 90-101 JAE that I built for Kevin runs. There are still parts out there for these engines and they work well as a reliable choice and not over priced as some are. I still have a OPS 67 with the aeromarine drum conversion that I got from Gerry Pisen????? Al can help on the spelling. He was a great guy that has left us too early!

Brad

 

[tom galdys]

As you all may know, I build and run OPS 45's 67's and 80''s. Yes there is a problem with thecarbs loosening up and JB weld is the way to go. As far as the rods go, they really don't need to be bushed at the top as they don't spin. There is not much movement inside the piston. As far as the crank pin area is concerned, I press a piece of brass through a hole drilled thru the bottom of the rod. The main reason for failure after you break your 1st rod is the fact that your old rod bushing is impregnated on the crank pin and grabs the bushing on the new rod causing it to spin and thus another spent rod. If you lose a rod because it broke at the crank pin, scrape the old bushing off the crankpin. It is there and sraping it with an exacto blade and polishing the pin will end your problem. Don't worry about hurting the crank pin, it is hardened and if you clean it up thoroughly, it will last a long time

 

[charles siler]

http://www.intlwaters.com/index.php?showtopic=52753

 

[Anders_Martinelle]

I can tell you another thing about the OPS 45 engines that is not so good but it`s possible to fix quite easy.

I found that the "front" housing or the part the crankshaft sits in is not correctly made so the rod do not line in the center of the engine.

What i made is a tool that you just fit in the cylinder bore and have a pin that his the crank and then you see if the engine is in line....

We use the 5cc engine in tethercar racing (that use most parts of the 45 engine) and there are rare that the rods break even that we run them well past 32000 RPM.

Also we have steel or made new housings for the crank, that is a weak point of the 45 engine.

I can only say that they work good if you take care of them

Anders

 

[Jim Allen]

Anders,

"Also we have steel or made new housings for the crank, that is a weak point of the 45 engine." I agree with your statement about the value of a steel front end compared to any aluminum front end & the improvement in performance that can be found. For many years I have used a full hardened steel (63+ Rockwell), fully ground, steel front end on my engines. No "Loctite" or shrink fit is used to mount the high clearance bearings used & interference amounts of .0008" are used without any problems.

Jim Allen

 

[Ray Sametz]

Anders,

"Also we have steel or made new housings for the crank, that is a weak point of the 45 engine." I agree with your statement about the value of a steel front end compared to any aluminum front end & the improvement in performance that can be found. For many years I have used a full hardened steel (63+ Rockwell), fully ground, steel front end on my engines. No "Loctite" or shrink fit is used to mount the high clearance bearings used & interference amounts of .0008" are used without any problems.

Jim Allen

Brings back memories of cutting S/S bearing housings in Charneys basement. 21 K&b, 45, 67-80 OPS, chroming and honing sleeves. Those 3 piece cases were a challenge. Ahh the good old days, fun times.

==={}

 

[Jim Allen]

Ray, I talked to Brian a few weeks ago. He sent me a video of his most recent outstanding project, a home made CNC router.

JA

 

[David Bryant]

"Also we have steel or made new housings for the crank, that is a weak point of the 45 engine." I agree with your statement about the value of a steel front end compared to any aluminum front end & the improvement in performance that can be found. For many years I have used a full hardened steel (63+ Rockwell), fully ground, steel front end on my engines. No "Loctite" or shrink fit is used to mount the high clearance bearings used & interference amounts of .0008" are used without any problems.

thanks for all the constructive input, especially in regards to crankshaft housing details.

I recently aquired a few brand-new packages of Aeromarine "Roller Bearings" designated for an OPS .45 marine (for practically nothing). I figured these were roller-type equivalents, and I'd just use them as replacements. When I received the parts I then realized these were actually "roller" bearings- rollers, no balls (yeah, I know

) . However, they are double-wide (depth-wise). I did'nt (easily) realize this from the original images from the ad (2nd image below). My natural thought is there must be a custom after-market crankshaft housing part designed to use these bearings? A vintage Aeromarine after-market part?

 

[Jim Allen]

David,

An important point to keep in mind is the amount of radial movement of the crankshaft at different places along it's length which is caused by the ignition of the motor. For this reason & due to the fact that a roller bearing cannot accept axial loads, I would not consider the use of any type of roller bearing when using a cantilevered type crankshaft. Some insight about cantilevered crankshaft bending can be found in "The FMV Story" by Enrico Flores, Rob Metkeijer & Hans Visser. There is also some in depth information on how & why a steel front end is better than a bar stock aluminum front end.

JA

 

[dwilfong]

I can attest to how much a cantilever crank can flex.........................

On my VAC 1.05 build up even with .012 head clearance the heavy piston/pin set up still touched the head button...................

Some my have bin from the lose clearance of the bearings and the wrist pin. But that still would not account for enough to make up .012 head clearance.

There where more than likely other contributing factors but I feel the crank flexing was the worst of them.

 

[Jim Allen]

The posted illustration shows the approximate movements of an 8 mm crankshaft. A larger, stronger, 15 mm crankshaft will have less movement, but still of the same magnitude. This radial movement makes placement of the front ends seal for cantilevered crankshaft engines critical in order to give the necessary sealing without touching. Numbers given on the illustration are not exact because peak pressures in the combustion chamber are not known. The point of no movement would be independent of the actual forces, but would be determined by crankshaft stiffness & bearings used. The bending will also effect the valve used on the rear of the engine.

JA

 

[Terry Keeley]

I can attest to how much a cantilever crank can flex.........................

On my VAC 1.05 build up even with .012 head clearance the heavy piston/pin set up still touched the head button...................

Some my have bin from the lose clearance of the bearings and the wrist pin. But that still would not account for enough to make up .012 head clearance.

There where more than likely other contributing factors but I feel the crank flexing was the worst of them.

Piston expansion...

 

[dwilfong]

No I don't think that was a factor as it was the same billet piston used in my 1.01 and ran that as close as .006 with no problem.

 

[Terry Keeley]

It might be the crank flexing but the rub marks I've seen in the sealing area would indicate the flex is mainly on the power stroke.

Maybe you're 101 wasn't running as hot? Or has less rod/pin slop?