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I'll be as concise as possible.
1965 421cu.in. Tripower GTO
and
1970 Roadrunner 440 6bbl
I have finally had success, so far, with the Roadrunner!
I bought the right electronic parts, 2x 70 amp relays, 2x 30 amp circuit breakers, heavy gauge wiring, 140 amp alternator.
The vendor my wife and I bought $5K worth of product from and Sam, the owner of Cooling Components brand electric fan and shroud assemblies have thus far left me with 2 Cooling Components brand primary cooling system radiator fans and neither have worked for either car. I have to say that I believe the 421 has a Pontiac specific problem in the gap between the water pump impeller vanes and the divider plate is too big. It is going to require removing/moving many of the Wraptor components and main mounting bracket (billet aluminum) in order to get the front half of the water pump off and the divider plate, and then I can check the gap. I absolutely think that I am going to find the gap larger than 1/10th inch, and a 70+ page thread on the Pontiac forum addresses that issue, and that small of a gap is critical for proper water pump function. My point is it may not be the 16" fan but that gap is the reason why the GTO ran hot, as it now has a large blade flex fan and it is running around 202-215 on the Interstate. Temps don't run quite as high at lower RPMs.
On to the Roadrunner...
I had Cooling Components largest, highest CFM electric fan and shroud assembly on my 26" Cold Case radiator. The 17" two speed fan and shroud assembly pulled enough air (3,600 CFM) on high speed through the radiator and AC condenser to hold a shop rag against the condenser, which is a "benchmark" the shop owner uses as a general pass/fail for fans. The problem is I had 3 fan motors burn up, and I'm out $350 for the fan, $200 for next day AM delivery of fan motor #2, and before I installed fan motor #3, I found a critical ground with a major problem. The small gauge battery ground wire termination was not grounded. The outer jacket of that wire was the only thing crimped in the eyelet termination, none of the wire. So both me and Sam, the fan manufacturer who was working with me on troubleshooting the problem figured that had been the reason why the fan motors had burned up, and in went fan motor #3, another $100...That fan motor burned up about 30 minutes into my drive, whereas the first 2 had lasted about an hour, so instead of the ground problem being resolved making things better, things were worse.
Because it's a 2 speed fan, it has 3 wires, 2 +12 VDC power wires and 1 negative ground. One 70 amp relay fed one 12V power wire and the other 70 amp relay fed the 2nd power wire. The ground went straight to the battery per the manufacturer. Each 70 amp relay has a 30 amp circuit breaker for over current protection. Every time the fan motor burned up, the process was the same: I smell the fan motor burning, and about 30 seconds later the MAIN 200 amp breaker would trip, shutting down power to the whole car. No wires got hot, the 30 amp breakers don't trip, and I have no idea why. While it was working, it kept the temps in a fair range, appx 190-204, but with a 180° thermostat, and an aluminum 541 cu.in. 6XX HP/TQ stroker in the works, and never having used the AC, "fair" performance isn't good enough. My engine actually ran cooler at 50-70 MPH without the fan than with it. So I have no faith in an electric fan as my primary cooling system radiator fan, and that leads me to where I am now...
I tried a Durale 17" low profile flex fan, not the full size blade flex fan, but because of the limited 3" of space between the Wraptor components and the rear of the radiator, it's got smaller, less efficient triangle shaped blades.
This is the full size blade flex fan I'm using on the GTO right now:
and this is the Durale flex fan I'm using on my Roadrunner:
It does a great job when cooling is "easy" like driving 40 mph or faster. I am going to get a factory fan shroud and trim it down to have the fan positioned in the opening in the most efficient way, roughly half way in the rear opening edge, and half out. I found the 17" fan failed to maintain an acceptable temperature in slow moving traffic or stopped. Temps got in the mid 220s with the AC off, and that is way too hot.
I decided to get the 18" size, and that is my final step for the main cooling system fan, as I have utterly no confidence in an electric fan in that position. If adding the shroud keeps the engine from hitting the 205 or higher mark, I'd feel better, under 200 would be great. I added 2x SPAL 790 CFM 10" pusher fans to the AC condenser. One comes on at 185° and the 2nd one kicks in at 190°. Those are the settings I have chosen to start with. They both come on when the AC is on, and they shut off at 55 mph because they aren't needed. I'll tweak the settings for them to run as little as possible, yet maintaining 190° or less is ideal to me. I am still going to add the shroud, but what I've found so far are temps from 185-192, and no problem sitting still with the AC on.
So thanks to Cold Case, Durale, and SPAL for making really good products.
The 2x SPAL fans fit like Plymouth could have installed them on the assembly line.
1965 421cu.in. Tripower GTO
and
1970 Roadrunner 440 6bbl
I have finally had success, so far, with the Roadrunner!
I bought the right electronic parts, 2x 70 amp relays, 2x 30 amp circuit breakers, heavy gauge wiring, 140 amp alternator.
The vendor my wife and I bought $5K worth of product from and Sam, the owner of Cooling Components brand electric fan and shroud assemblies have thus far left me with 2 Cooling Components brand primary cooling system radiator fans and neither have worked for either car. I have to say that I believe the 421 has a Pontiac specific problem in the gap between the water pump impeller vanes and the divider plate is too big. It is going to require removing/moving many of the Wraptor components and main mounting bracket (billet aluminum) in order to get the front half of the water pump off and the divider plate, and then I can check the gap. I absolutely think that I am going to find the gap larger than 1/10th inch, and a 70+ page thread on the Pontiac forum addresses that issue, and that small of a gap is critical for proper water pump function. My point is it may not be the 16" fan but that gap is the reason why the GTO ran hot, as it now has a large blade flex fan and it is running around 202-215 on the Interstate. Temps don't run quite as high at lower RPMs.
On to the Roadrunner...
I had Cooling Components largest, highest CFM electric fan and shroud assembly on my 26" Cold Case radiator. The 17" two speed fan and shroud assembly pulled enough air (3,600 CFM) on high speed through the radiator and AC condenser to hold a shop rag against the condenser, which is a "benchmark" the shop owner uses as a general pass/fail for fans. The problem is I had 3 fan motors burn up, and I'm out $350 for the fan, $200 for next day AM delivery of fan motor #2, and before I installed fan motor #3, I found a critical ground with a major problem. The small gauge battery ground wire termination was not grounded. The outer jacket of that wire was the only thing crimped in the eyelet termination, none of the wire. So both me and Sam, the fan manufacturer who was working with me on troubleshooting the problem figured that had been the reason why the fan motors had burned up, and in went fan motor #3, another $100...That fan motor burned up about 30 minutes into my drive, whereas the first 2 had lasted about an hour, so instead of the ground problem being resolved making things better, things were worse.
Because it's a 2 speed fan, it has 3 wires, 2 +12 VDC power wires and 1 negative ground. One 70 amp relay fed one 12V power wire and the other 70 amp relay fed the 2nd power wire. The ground went straight to the battery per the manufacturer. Each 70 amp relay has a 30 amp circuit breaker for over current protection. Every time the fan motor burned up, the process was the same: I smell the fan motor burning, and about 30 seconds later the MAIN 200 amp breaker would trip, shutting down power to the whole car. No wires got hot, the 30 amp breakers don't trip, and I have no idea why. While it was working, it kept the temps in a fair range, appx 190-204, but with a 180° thermostat, and an aluminum 541 cu.in. 6XX HP/TQ stroker in the works, and never having used the AC, "fair" performance isn't good enough. My engine actually ran cooler at 50-70 MPH without the fan than with it. So I have no faith in an electric fan as my primary cooling system radiator fan, and that leads me to where I am now...
I tried a Durale 17" low profile flex fan, not the full size blade flex fan, but because of the limited 3" of space between the Wraptor components and the rear of the radiator, it's got smaller, less efficient triangle shaped blades.
This is the full size blade flex fan I'm using on the GTO right now:
and this is the Durale flex fan I'm using on my Roadrunner:
It does a great job when cooling is "easy" like driving 40 mph or faster. I am going to get a factory fan shroud and trim it down to have the fan positioned in the opening in the most efficient way, roughly half way in the rear opening edge, and half out. I found the 17" fan failed to maintain an acceptable temperature in slow moving traffic or stopped. Temps got in the mid 220s with the AC off, and that is way too hot.
I decided to get the 18" size, and that is my final step for the main cooling system fan, as I have utterly no confidence in an electric fan in that position. If adding the shroud keeps the engine from hitting the 205 or higher mark, I'd feel better, under 200 would be great. I added 2x SPAL 790 CFM 10" pusher fans to the AC condenser. One comes on at 185° and the 2nd one kicks in at 190°. Those are the settings I have chosen to start with. They both come on when the AC is on, and they shut off at 55 mph because they aren't needed. I'll tweak the settings for them to run as little as possible, yet maintaining 190° or less is ideal to me. I am still going to add the shroud, but what I've found so far are temps from 185-192, and no problem sitting still with the AC on.
So thanks to Cold Case, Durale, and SPAL for making really good products.
The 2x SPAL fans fit like Plymouth could have installed them on the assembly line.
and 
for the Durale flex fan and to a greater extent the 
