Model 20 Overheating Problems

[KenHupp20]

In reading the discussion on adding a fan it seems that some Hupps overheat and some do not. I have examined a several blocks and have noticed on some there is a considerable amount of casting flash in the water jacket right near the crest of the top ( looking inside the top water opening). That of course being at the worst possible place.It protrudes horizontally about 3/4" from the wall of the cylinder. The flash seems to be more on the rear cylinder. In other blocks the inside of the water jacket appears much more open ( clean in casting terms).

I would like to hear what others think on the topic.

Could this "obstruction" be enough to cause some to run hot ,and some cool?

Thanks, Ken

[KenHupp20]

It took some doing but I have solved the overheating problem.I had a spare set of jugs machined and have installed them. The engine now runs @ 190 degrees, no other changes were made.

The casting flash was the problem.

I believe the "optional " or added fan was an attempt by HMC to take care of the problem,an early factory recall you might say .My car is #1175 fairly early, I suspect Hupp found and corrected the problem in the cores for the casting later on, so the problem likely occurs only on earlier Hupps.

[Tom400CFI]

This is a good post. GREAT info!!

-Tom