[AG]

I use a Mark VIII fan in my race car with a 75 amp relay and always run it on high speed, works well.

[RocktimusPryme]

I love a good zombie thread.

Originally Posted by AG

I use a Mark VIII fan in my race car with a 75 amp relay and always run it on high speed, works well.

Do you have a legit Ford Mark VIII fan or an aftermarket replacement?

IIRC correctly the cool part about the testing I posted was that the Dorman unit actually seemed to run on a reasonable level against the FOMOCO unit. I cant imagine Mark VIIIs had a big production run anyway, so not only are the fans left out there not all that plentiful, but they now have 20+ years of abuse on them. A reasonable off the shelf replacement is welcome.

Originally Posted by android 211

I found it interesting that the guy with the 71 'vert/455 went from factory setup (7 blade factory fan and Hayden clutch) to a Flex A Lite fan and it got cooler.

Ill never not believe that there isn't some level of black magic to keeping old cars cool. There are just so many variables that can go unseen, and so many of these old cars have been cobbled together over decades. Joe Average Car Guy complains that he cant get his car to run cool and follows all the cooling system advice but nothing works. Little does he know his car is running too lean and with too little timing. Or a Pontiac guy who has a WP backing plate way out of wack. Google is probably never going to tell him that he needs to clearance that plate.

My 62 Cat has a cheap three row radiator in it. Strike 1, we all know the big two rows should be better. It has no shroud, just an open clutch fan. Strike 2 we all know that's wrong. And strike 3, it has a bunch of air gaps between the radiator and core support. But that darn thing runs a few degrees under its 160* thermostat (just what I had laying around).

Meanwhile the MUCH better supported engine in my firebird struggles a little if you get caught sitting at idle for too long.

Is it because the turd of an olds 455 in the 62 just doesn't produce enough power to make any heat? Do Oldsmobile big blocks have superior cooling tendencies? Ive always wondered that but never seen a study. When you have differences in design of cooling ports and passages in different engines you HAVE to have differences in cooling capability. So it stands to reason some engines would just stay cooler by design than others. I don't know which ones.

And as mentioned in another thread in the cooling section, most of these old cars just flat out didn't come with big enough radiators. When compared to cars from the 80s and up, radiators started to get more fontal surface area. The radiator for a 3.8 liter 90s grand prix has more frontal surface area than the "big block" sized first gen F body radiator from Cold Case.

[Squidward]

Agree totally. I've wondered "WHY THIS? but "NOT THAT?"

Basic principles of heat transfer are immutable.

More flow on any side of the equation is always better. Period.
More surface area for heat transfer is always better.
You can overcome a deficiency in one attribute by engineering in an excess of another.

If you have a small surface area radiator, you better have a lot of airflow thru that radiator to bring down the radiator outlet temp as much as possible. That's what I am dealing with now.

It's funny how first gens have all sorts of baffles to direct air, yet 2nd gens and A bodies had little of that other than a fan shroud. It tells us that the design engineers knew there was a serious constraint related to that platform. 1st Gen radiators are so comparatively tiny. Tiny radiator means that airflow capable of cooling a 2nd Gen is not enough to crutch a 1st gen.