My Willys had a Buick V6 conversion sometime in the 1970's.  Apparently the donor was a Monza.  How do I figure out if this is a 225 or a 231?  The radiator looks like the original from 1952 and it has no shroud.  I am assuming that the engine will cool much better with a shroud forcing the air through the radiator so I'll probably have to upgrade the rad too. Recommendations?

Gerry  

I run a Monza V6 radiator behind my 225 odd-fire with standard fan and a 160 stat. No shroud but I did add an auxillary 10" pusher fan because of the winch and for extreme hot weather crawling. Only on the hottest days and slowest up hill crawling does the auxillary pusher fan ever come on. The auxillary fan is set for 180 on and is also good for shut down spikes and auto shut down is set for 140. Works for me in the real world.


 

Absolutely, always use a fan shroud.  A properly shrouded engine driven fan with a clutch is the best setup you can use.  Electric fans are for limitations that make an engine driven fan not possible. What truck comes from the factory without a shrouded engine driven fan. Trucks are very different than cars with regard to cooling needs. Don’t let the light duty cooling needs of a car influence you. CFM from an engine driven fan is much greater than any electric fan setup. And a sucker fan with identical  CFM as a pusher fan, is more efficient.  That’s why you see electric fans used as suckers, and not pushers for the primary cooling needs of a car. There are situations that an electric pusher fan is used to supplement cooling needs, but that is not a starting point. Most notably with A/C. The starting point is a properly shrouded engine fan.  A cooling setup that WORKS maintains a constant engine temperature.  And that is dictated by the thermostat. Just because it is not overheating does not mean it is working. A constant temperature is important for engine longevity. An engine that is running a 40f differential  is not being cooled properly. There would be a lot of expansion and contraction going on (stress). If there is enough cooling going down the road at 50mph, then the radiator is properly sized. If the temp gauge starts moving up when going slow (4x4’n) then there is an airflow issue. Almost every time I encounter someone out on the trail with overheating problems, it’s an engine conversion without a shrouded engine driven fan. And yes, they often have electric pusher fans.  There are many variables in cooling. The most difficult set of variables to solve is a slow moving 4x4. They have to have the best assisted airflow possible, and that is an engine driven clutch fan.