pony motor right hand cylinder has seemed to tossed a rod ..I am looking at converting to direct start though I am in colder weather after October . The ? I have instead of blocking old cooling ports I want to adapt a plate with a inline 120 v heater recirc pump....is it okay to drill and tap for plate around original opening . I will be using the generator exhaust with quick adapter to to preheat air intake figured I could kill two birds with one stone

you should look into installing a flame starter like the cummins engines use. cost about 30 dollars .

www.amazon.com/Perkins-Manifold-Pre-Heat...ostart/dp/B01MRRUPVN

Typically the top of the clutch housing where the pony motor sat is used for the battery box, so you might want to plan your connections so as to not interfere with that. I can’t think of anything preventing you drilling holes and tapping the cast iron around either coolant port. A coolant heater should have good circulation from bottom of water jacket around #4 cylinder through the heater and out into the head around the precombustion chambers. You have to block those ports somehow anyway.

Fitting that sort of heater in other locations isn’t real easy on the old engines. It’s been done before, just not a lot of existing ports to plumb it into.

i'm not a fan of circulating heaters...much prefer actual block heater element type that actually keep the frost out of the engine block...the heat is internal where it does the most good...

-those intake flame-throwers sound very reasonable for a source of quick heat:flame:

the Kim hot start is a recirculating heater. Will bring your engine up to 180 degree. Hook up 1 hose up by thermostat and the other at the bottom of the water gally. Not cheap though. CB120 without thermostat is $ 250.00. Dad had one he turned on from inside the house for his Pete. When he would go to start after 1/2 hr, the hot light was on on his dash. The whole radiator would also be warm.