Reply To: What should I beware of in restoring a 1979 4hp Johnsons Model 4BR79Donohnson

[Don]

Yes, this 79 model is full of needle bearings everywhere…So, using 50:1 is not an issue, there are no plain rod bushings/bearings to worry about. That being said, I’m not sure this isn’t a bit of overkill on this small engine though. These engines tend to be a bit more noisey, due to a loose fit on some of the needle bearings… The CDII ignition is overkill also…
I didn’t see the pictures, did you post some? Maybe my computer is tired…
In any event, I surely would not pull the powerhead apart, not necessary unless there is obvious piston cylinder damage or rust to the bearings. If you want to have a better look, pull off the intake manifold and peek inside at the rods…But, I would certainly pull off the head and the exhaust cover…These engines have tiny water passages that plug easily. The cooling systems are a little more complicated than the older ones also.. Some of the cylinders have rubber restrictor plugs, etc. I would have to review a parts list to remember, but am pretty sure the head gasket is a little different also…
Pull the gearcase, do the water pump assembly complete. Please be sure to replace the driveshaft upper oring and lube the splines generously with OMC moly lube. Post more pictures, don’t know why I can not see the ones you have posted already…D