I thought I would document something new that I learned on the latest Block Heater install I did.  I recently acquired a 1968 190XT and I had previously installed a freeze plug style block heater in a 1967 190XT.  I thought the same Zero Start block heater plug would work for both tractors but I was wrong.  

After knocking out the freeze plug very easily with a hammer and punch, the 1 1/4 size block heater used on the 1967 was too small.  I measured the diameter of the 1968 block hole and it was 1 3/8.  It also had no inner lip on the block casting as the 67 had.  So, I now had to find a larger diameter block heater.  Zerostart and Katz wants you to pick your engine and then you are told what part number works.  Well, that doesn't work on old Allis tractors.  They aren't listed.  

Turns out that using a 35MM block heater meant for a 4 cylinder Perkins engine is the perfect match for the 1 3/8 inch hole.  Zerostart Item Number i used with great success is 310-0027 in case anyone runs into this size difference.  This model is 600 watts and it gets oriented at 3PM once inserted into the hole.  There were some 35 MM 400 watt versions that may have worked but I wanted the higher heat output.

Even using the manifold heater and waiting after counting to 100 before trying to start, I could not get the 1968 190xt to start in cold weather.  Now, after warming the engine for about an hour, it starts right up.  These casting holes obviously vary greatly.

The one kink I had in this process was the butterfly drain on the bottom of the radiator does not allow the antifreeze to drain out.  Seems to be plugged.  So, part  of the antifreeze ran out when the freeze plug was removed into a bucket below the engine.  Not sure what to do about the drain plug at this point.  I would like to get the pink anti-cavitation antifreeze in it at some point.  I guess I could remove the lower radiator hose?

Anyway, a success with the usual twists.   Hope this helps others that may want to install a block heater into a 190xt.  If you are in a cold climate and can't put it in a heated barn, it is better than  splicing a tank heater into your heater hoses.  It heats up faster than a tank heater too.