[roy381]

So, my 67 gto had factory air. This I know because I removed it. I'm doing a radiator upgrade and ordered the taller 17.5 radiator from Cold Case. As it turns out my core support is a 15.5 support. Any reason to believe it wasn't changed out because of an accident?

Thanks in advance.

[steve25]

Do you have a plastic fan shroud?

[roy381]

Yes it does

[b-man]

Very common to find the core support has been switched due to collision repairs.

I had a ‘67 GTO with factory air conditioning and it no longer had the correct core support either. A previous repair involved replacing it with a standard 15-1/2” support and extending the bottom to accept the 17-1/2” radiator, it didn’t look very nice but it was functional.

I’m pretty sure Ames sells a kit to make an air conditioning support from a standard one and it will look like the correct factory support when you’re finished installing the bottom piece they sell.

[steve25]

The plastic shroud is said to be only for a/c / towing and police cars which means the bigger support that you do not have.

So how does that shroud fit right?

[pontiacs-r-us]

Originally Posted by b-man

Very common to find the core support has been switched due to collision repairs.

I’m pretty sure Ames sells a kit to make an air conditioning support from a standard one and it will look like the correct factory support when you’re finished installing the bottom piece they sell.

The kit may be available from Coldcase also (?) I remember Chris talking about doing them a few yrs back…

[i82much]

how much difference does the bigger radiator make in terms of keeping the engine cool?

[b-man]

Well it must have helped enough to the degree that the factory spent the money to design the bigger radiator and support as well as baffling to direct air flow through the radiator for air conditioned cars as well as for certain performance engine options.

It’s probably somewhere around 10 or 15 degrees which of course counts when you’re on the edge of staying cool enough with the additional load of running A/C.

[roy381]

So, I was putting the new radiator in when I realized the issue with the new one sitting 2" taller than the old one. I believe the shroud fit fine but will double check today. That was my next question as to cooling. They do make an extension to drop the support 2" for around $275 plus I would have to pay to have it welded up. Or I can buy the standard 55.5 radiator and try to resell the 17.5 cold case radiator. I 'm swapping out the original 400 with a 9.3 compression 461 roller. I would assume the lower compression roller should run cooler. I had issues with the 400 temps running 210-220. would it be wise to stick with the taller core and add the extension. Or would I be safe with the standard core. Let me add I will be adding Vintage Air at some point.

[steve25]

Wrong logic!
When properly tuned and not taking full advantage of its extra power a high comp motor will always run cooler then a low comp motor.

This fact will add more BTU’s to your cooling system, that being a 461 is 13% larger then a 400.
Mainly that near 1/2” longer stroke of the 461 makes more heat due to friction.

[roy381]

Well, that's why I come to this site before I do anything

Thanks Steve!

[steve25]

To be fair about it, there are situations where a low comp motor will run cooler then a high comp.

As in lets say a low comp motor is pumping out thru a very efficient exh system that is good Thru out its whole rpm range, and a high comp motor at the rpm where it’s now making more power then the low comp motor is now trying to pump itself out thru a restriction, that then is a problem.

[roy381]

So that being said. I assume the larger core radiator would be more beneficial?