I wanted to follow up with my post and give an update on what’s happening on my end. After reviewing the information everyone provided, I was ready to go with a Derale dual fan set up using my current radiator and give that a try. Right before I was getting ready to place my order, I started reading an article on Summit’s website about fan /shroud location. This caused me to question my decision and I decided to talk to their tech support group first before placing my order.
After a few minutes’ discussion, it was decided that my current fan – shroud set up is wrong. My fan is protruding too far into the shroud and is most likely the cause of my higher temperatures at idle. Although it is moving air it is also causing a lot of turbulence especially at idle. The fan should be about half in/half out the opening of the shroud and mine is currently 2 inches beyond the opening into the shroud. The fan blade currently has a 2” spacer so it was decided to go to a ½” spacer to bring the fan out of the shroud some. Although it will still be in deeper than preferred, he thinks it will help solve my issue. He also mentioned that if I still needed a little more air flow to add a small pusher fan to the front of the radiator instead of replacing everything. See pictures below.
So why do I have this problem to start with -The car has had a 460 installed which is the same block as the 429. The 71 429’s came with a 19” fan blade and a D0OE-8146-D fan shroud to accommodate this bigger blade and its projection. I currently have an 18” blade and a D1ZE-8146-AA shroud which is for a 351. The difference between the blade size and shroud are the main culprits. My radiator is the correct one for a 429 and is 3 rows with 13 fins per inch. I’m going to try the spacer first and see what happens. If it doesn’t work, then I’ll decide what way I’m going to go. The spacer is $30 and stands a good chance of improving things. Pusher fan is $95. I checked into a reproduction shroud, and they run between $100 to $200. The cheaper ones out there have some low reviews saying they deform due to the engine heat. The $200 ones are currently on back order at all the sites that sell them. The 19” fan blade is $65.
The last thing I have done to is to flush my radiator and block again. I had just flushed my cooling system last year with Prestone radiator flush and cleaner. I decided to go a little different route this time. I used Evapo-Rust TC001 Thermocure Coolant System Rust Remover. I will have to say this stuff does work. Following the directions, I took the car out for a nice 2-hour drive. I stopped and had lunch and then drove for another hour. Burnt up about $50 in gas lol. Drained and backed flushed the cooling system for about 10 minutes and then refilled with fresh anti-freeze and distilled water.
The weather has cooled down this past week and I haven’t been able to see if changing the spacer has made any difference. I took the car out for a short drive and it ran tops at about 185. I did leave the engine run at an idle for about 10 minutes and it held at 178 to 180. My thermostat is a 180 so that’s a good sign.
I would like to thank everyone for the pictures and input. A lot of good information was provided by everyone, and some good ideas were shared. I learned a lot and will be utilizing it in the future if the need arises.