Now that summer is on it's way, I am thinking about making additional improvements to my TBird's cooling system. I already have an aluminum radiator and electric fan.  Made a big difference.  There are a number of additional modification available. Casco sells a water pump with deeper fins.  I believe this is to compensate for the TBird spacer.  They also make a smaller water pump pully which is supposed to improve flow at idle.  I have also seen an improved spacer. My issue is only when sitting in traffic on a hot day.   As soon as I move, the temp returns to normal. Any input?

After all that you already did and the only issue is a creeping temp when sitting idling, I would go for the smaller pulley first. Not to be lazy but that does seem to be what's needed in this case. Can you see a good rapid flow at idle with the cap off?  Does the flow increase substantially when the idle is picked up?  I'm pretty sure you have an electric fan so noise from an increase in fan speed won't be an issue. Hope this helps, JEFF...........

64F100 57FAIRLANE500

No fan will help if the coolant is not circulating at idle. Chris Ames's WP spacer addresses that. I have his spacer, but don't intend to use it until my engine is rebuilt. Chris is a nice guy and will talk your ear off, if you give him a call.
The smaller pulley would be the easiest repair, so I will wait until I know if it's needed. 

Not a Thunderbird but all my over heating in traffic was GONE with a 302 Mustang water pump pulley. All was bought from Summit, chrome was ruffed up and painted black. A spacer kit was also bought to help with belt alignment.

At idle there was no movement of water evident looking in the radiator. With the new pulley there was sufficient movement to keep creeping up temperature. I give all credit to greenbird on this site for tell me to do this 5 years ago. I do have the 1/8” hole in the plug I put in the bypass line 3 years earlier.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

How much smaller is the Mustang wp pulley?

The stock one is over 7” the Mustang is right 6” outside diameter. I believe Ted said once there were different diameters for different parts of the country.
Some have had concerns about to many rpm on the pump and cavitation. I suppose this could be a problem if drive at 5000 rpm continually. Think about your alternator or generator and how small the pulley is. I had the stock 3.21 gears in for 4 years before changing rear ends to a 2.74.

56 Vic, B'Ville 200 MPH Club Member, So Cal.

From when I did the innovators west damper install, I found something like 7000 - 8000rpm max for a water pump and 18000 rpm for an alternator.  The water pump RPM limit should be taken with a grain of salt since the only "official" spec I found was in Stewart Components tech section and they make performance pumps which may sustain higher rpm than a stock replacement pump.  The other pump specs were "from the internet" and we all know how reliable that can be.  The alternator rpm came from Powermaster, in regards to a street alternator so that one is probably pretty reliable.

Since this is a cooling thread, the vast majority of street ys with a stock damper will not exceed that pump rpm with any readily available pulley and it should not be a concern.


Lawrenceville, GA

I had the same thoughts about cavitation at higher rpm, but I don't drag race, and I haven't gotten a speeding ticket since I don't know when. 

Interesting you swapped rear gears. I swapped my 55 T-bird's OEM 3.31 gears for 2.72 gears. I'm also building a C4 transmission/w Dynamic Racing Transmission's wide-ratio gear set. Going from Fordomatic's 2.40 1st/low gear to 2.90 in the C4. With the 2.90 1st, it will be equivalent to 3.28 rear gears/w the Fordomatic. In other words, I shouldn't notice a difference until I reach 3rd, which will put me at about 2200 rpm @ 65 mph. There will be a wider gap, however, between 1st and 2nd, with 2nd being 1.60. Hopefully, it will be an easier swap than trying to install an AOD. I have the Flat-O Products C4 adapter kit.

Hi Phil, if you have the original timing chain extension “water pump spacer” there is an internal flaw in its design that diminishes water pump flow and contributes to overheating at idle. As was mentioned by 55blacktie Chris Ames did formal thermal dynamics testing on a prototype he developed, and proved his theory. Chris published the results of coolant flow tests at specific engine RPMs, comparing the original spacer with his design, the results are quite impressive. I was one of the early purchasers of his replacement and met him in person at a regional in New Jersey a couple years back. I have it installed in my 312 and it’s all he says it is. I have a six blade clutch fan, Griffen aluminum radiator and a 170 degree thermostat. With Chris’s spacer I don’t run over 170 degrees which is approximately 4 fifths of the way to the end of the solid white line, the end of which is 190 degrees while in motion. In heavy stop and go traffic it can get to 190 or slightly over, but 190 is nothing and when moving again the temperature quickly drops back to normal. I would recommend sticking with your water pump as a “high flow” pump will mask but not correct the design flaw in the spacer. While there are a number of things that can contribute to our Y blocks overheating Chris’s spacer hits one right on the nose. I highly recommend it 🚗.




1955 312 T-Bird Warwick, NY

Phil, if you contact Chris, he will probably tell you to check for casting flash around the coolant port of the timing cover, which restricts flow.