Operation "Plantain Repower" was a success, but...

So on Labor Day weekend this year my 1972 50 HP Evinrude shot a piece of piston skirt through the crankcase, ending its time with me (I have since sold the entire motor to a guy who needed a new drive shaft and a cache of working parts). I repowered my 1976 Yarcraft Yankee with a 1976 70 HP (70EL76D) Johnson (Goodbye electric shift). After doing some basic checks on the motor, determining that the rectifier was bad and replacing, I finally put it on the water yesterday for final system checks. I am pleased to report that it ran perfectly; with the standard 17P prop, she idled at about 700-900 RPM in gear (tach is not graduated fine enough to tell more than I was above 500 RPM, and below 1000), WOT @ 5500 RPM 32 MPH by GPS, Cruises at 5000 RPM at 28-30 MPH. Jumps on plane like it never did with the 50. Amazing how well a rig performs when you max out the power the hull is rated for.

The only concern I have with the motor is the cooling/water circulation. On the lake, I noted that I am still not seeing a ton of water coming out of the exhaust relief ports on the leg. I ran the motor WOT for about 5 min, then put it in neutral and using an IR thermometer read the temp on the head at 147 degrees. I am sure that the motor is not overheating in any case, but am concerned that there is some kind of blockage that is preventing the water from dumping out the exhaust relief ports. Is there an easy way to verify that they are clear? If I run some wire or a brush, or just flush out with a hose, will I be risking any damage to the motor that way? My worry is that some critter may have gotten up there while the motor was idle and there is either a wasp nest, or some such structure that may be impeding water flow out the ports. Any words of wisdom will be appreciated.

Rgds

Re: Operation "Plantain Repower" was a success, but...

Hi eavega. I was reading a similar post to yours last night. They suggested, and had great success, by running water through the exhaust system using a garden hose and following it up/alternating with compressed air.
Good that you checked the temp with your IR gun. It sounds like it's not getting too hot, and the numbers don't lie, so your probably ok. Also, depending on the make/model of the motor you may not get a perfectly steady stream of water out of the tell tale. It seems like most of the OMC motors from 50s-70s tend to spit/spray water mixed with their exhaust rather than a constant steady stream, which seem to be more prevalent on newer motors. Hope that helps ust some tips I've seen elsewhere here on the site.