OPS 0.67 Over Heating???

[Marc Pagé]

One of our club member has a new ops 0.67 installed on a Miss Maryland Lauterbach and after the breaking phase (5 tanks) the engine delivered a lot but cut after 3 turns (regular course) and everything aroud the engine and the engine is VERY HOT (flywheel, pipe, collet, coupling...)

The flex cable is free, the engine is well cooled by fresh water....and the carb is set well! The fuel is Biron with 15% oil and 40% nitro!

The exhaust is cooled first and the head after, could it be the only reason or is it not so important?

What can be the problem or the solution?

Thank's

 

[gil sonsino]

As your engine is enclosed in a scale boat I'd suggest you to refrig the head separately than the exhaust.Try larger ID water inlets and raise the oil content to 20% better for a .67 engine.

Gill

 

[Scott Schneider]

Do head first in summer, then ex coupler. take the factory water fittings out and THROW THEM AWAY ! Tap the head for 10-32 fittings and install new ones.

Next make sure you have LOTS of air flow going down into cowl and out the back.

If you have low air flow, the Ex system will get everything very hot inspite of good water flow.

I raced OPS .67's for over 10 years and your heat problem was typical untill water flow is increased threw the head.

Scott

 

[[email protected]]

I had a similar problem with that cowling, the inside of the cowl would pinch that line off slightly and really heat the motor up. Do like Scott said and make sure you use 90 degree fittings

 

[Chris Thomas]

Another area to look is the head shim- should be about 17-19 thou. Sounds big but the OPS motors likes it. I run Red-Max fuel it has the correct amount of oil with 40-50% Nitro. And yes cool the head first. Or run two lines "from the pickup". one to the head, one to the exhaust. If you are too thin on the fuel you will start burning up exhaust couplings. A pinhole exhaust leak will make it sputter on the third lap just as you described, too. It is also important to open up the water flow as Scott described.

 

[izitbrokeyet?]

Before you go trying a bunch of other stuff:

15% oil is definitely part of the problem. Those motors get a large part of their cooling from the oil content. 18-20% is where you'll want to be.

 

[zagustin]

Hi Marc,

YGM.

Regards

Werner