[sjdiesel]

Has anyone on here gone from a 1” to 1-1/4” two tube Aluminum radiator? If so do the larger tubes really cool that much better?
I currently have a Cold Case radiator with two 1” tubes (P/N RPE36L) and it struggles to keep my car cool on hot days. I am considering upgrading to their HO/SD radiator with two 1-1/4” tubes (P/N GPG34AS) but want to know if the additional tube thickness is worth it.

Since my GTO is a factory non-AC car with the 15.5” radiator, my other option is to modify my core support to fit the larger factory AC radiator that measures 17.5” (P/N GPG38AS). I really don’t want to cut up my core support if I absolutely don’t have to.

[Ccass]

1967 GTO 461 stroker motor dual quad intake motor and AC: With a US Radiator Desert cooler 4 row, factory shroud and 7 blade AC fan I could not sit in traffic on a 90 degree day for more than 25-30 minutes even with the AC off. I then installed a Rodney Red dual 1" aluminum radiator and removed the AC condenser. With this new rad, It improved things but now I had to pull over after about 45-60 minutes. I spewed fluid on the road several times in each scenario. So 250+ temps I then learned of dual 1 1/4" aluminum cores. For a total of $2000 I purchased this dual 1 1/4" rad and also had a custom dual spal fan and shroud installed. I've never run over 195 since!

As a side note, all of the above was before Cold Case existed. So 3 years ago, we installed the $7Cold Case GPG38ASK replacing the entire $2000 kit that solved my problem. Four years later, I have still never gone over 195 and that was in the hottest Summer stop and go traffic for extended time frame.

I've owned my 67 GTO since I was 18 and over the years experienced numberous overheating issues. Enough that a smart guy would have given up on Pontiacs! lol! On the other hand, 40 years of those experiences came in very handy when starting and running a radiator company!

[sjdiesel]

Did you re-install the AC condenser with the new radiator setup? Was all of this with larger 17.5” AC radiator?

[Ccass]

Originally Posted by sjdiesel

Did you re-install the AC condenser with the new radiator setup? Was all of this with larger 17.5” AC radiator?

I never did reinstall the condenser.

All was with the bigger 17" AC radiator size.

[chrisp]

Sounds like you have other issues with the problem, the current rad you have is sufficient.

[ID67goat]

Originally Posted by chrisp

Sounds like you have other issues with the problem, the current rad you have is sufficient.

Agree with this, what are the details on your car? What fan, fan shroud, pulleys, water pump, divider plate clearance? Running vacuum advance on your distributor?

[sjdiesel]

Originally Posted by chrisp

Sounds like you have other issues with the problem, the current rad you have is sufficient.

Out of curiosity, What makes you think the radiator I have now is sufficient? Everything I am reading suggests it isn’t.

468 stroker
8 bolt flow kooler pump from Butler
I don’t know the distance between the plate and pump because I didn’t put it together. A reputable Pontiac engine builder did. I assume it is correct. Although I have thought about pulling the pump off and double checking for my own peace of mind
6-1/2” water pump pulley
7-1/2” crank pulley
Timing is set to 20 initial, 36 total and light cruise is 42. This is all set via my Holley EFI setup.
Factory reproduction fan shroud that I put rubber around to seal it up against the radiator.
Hayden fan clutch that I modified the spring slightly on.
Factory 7 blade fan.

[Ccass]

The topic starter may very well have other issues. We've discussed a few options privately. My car may well have other issues after all of these years. My point is that sometimes you can chase gremlins and never find them. I tried for 5+ years. There may have been another solution that would have allowed me to keep a 4 row rad or a dual 1" aluminum but I couldn't find it. Maybe it was the way the motor was built? Who knows. But I and many others were able to solve the problem with volume..

[chrisp]

Originally Posted by sjdiesel

Out of curiosity, What makes you think the radiator I have now is sufficient? Everything I am reading suggests it isn’t.

468 stroker
8 bolt flow kooler pump from Butler
I don’t know the distance between the plate and pump because I didn’t put it together. A reputable Pontiac engine builder did. I assume it is correct. Although I have thought about pulling the pump off and double checking for my own peace of mind
6-1/2” water pump pulley
7-1/2” crank pulley
Timing is set to 20 initial, 36 total and light cruise is 42. This is all set via my Holley EFI setup.
Factory reproduction fan shroud that I put rubber around to seal it up against the radiator.
Hayden fan clutch that I modified the spring slightly on.
Factory 7 blade fan.

What temp @ idle & when in motion ?

[sjdiesel]

Originally Posted by chrisp

What temp @ idle & when in motion ?

It really depends on how hot it is out. But for reference it it was 88 out yesterday, I had the AC on and was sitting at a light. Temp creeped up to 220, light turned green and I jumped on the freeway. Temp dropped to 195-200 after a few miles going 65-70.

[sjdiesel]

I guess the bottom line is the temps increase when sitting idling no matter the outside weather. That makes me think the fan is not pulling enough air at idle RPM’s. I had a Derale 4K cfm electric dual fan setup that worked pretty good around town (except they were f’ing loud) but the engine heated up on the freeway. So I swapped out to the mechanical fan and temps were good on the freeway

[george kujanski]

If the temps creep up when idle you are not getting enuf air flow or coolant flow or both. Question: your 468 stroker...what block is that? A later block should use a 11 bolt pump. An 8 bolt pump usually needs a divider plate since they were used with an earlier block. If it's a later block, is it compatible with an 8 bolt pump?

just askin'

george

[ID67goat]

Originally Posted by sjdiesel

Out of curiosity, What makes you think the radiator I have now is sufficient? Everything I am reading suggests it isn’t.

468 stroker
8 bolt flow kooler pump from Butler
I don’t know the distance between the plate and pump because I didn’t put it together. A reputable Pontiac engine builder did. I assume it is correct. Although I have thought about pulling the pump off and double checking for my own peace of mind
6-1/2” water pump pulley
7-1/2” crank pulley
Timing is set to 20 initial, 36 total and light cruise is 42. This is all set via my Holley EFI setup.
Factory reproduction fan shroud that I put rubber around to seal it up against the radiator.
Hayden fan clutch that I modified the spring slightly on.
Factory 7 blade fan.

My car is setup very similar to yours except (Stroker, EFI, fan setup, timing, etc) except I am running Aluminum heads and the AC sized radiator (Griffin 1.25" dual row aluminum). No other AC components installed and manual trans car.

In 100 degree weather I have no issues with getting too hot (200 degrees max). When I went through this same thing, the biggest benefits I saw were with the Aluminum radiator, pump clearancing, and using vac advance (was just using MSD with mechanical adv. previously)

[JSchmitz]

Originally Posted by ID67goat

My car is setup very similar to yours except (Stroker, EFI, fan setup, timing, etc) except I am running Aluminum heads and the AC sized radiator (Griffin 1.25" dual row aluminum). No other AC components installed and manual trans car.

In 100 degree weather I have no issues with getting too hot (200 degrees max). When I went through this same thing, the biggest benefits I saw were with the Aluminum radiator, pump clearancing, and using vac advance (was just using MSD with mechanical adv. previously)

My car was easier to keep cool with the sick in it. Auto trans brings some heat to the party.

[PontiacJim1959]

Originally Posted by sjdiesel

It really depends on how hot it is out. But for reference it it was 88 out yesterday, I had the AC on and was sitting at a light. Temp creeped up to 220, light turned green and I jumped on the freeway. Temp dropped to 195-200 after a few miles going 65-70.

Here is my opinion.

- With the electric fans the engine was not cooling at speed because the size of the fan blades blocking air flow. You figured this one out.

- Timing. Is 20 Initial with/without a vacuum advance hooked up? Vacuum advance will help with engine cooling at idle/light engine throttle. It is needed for a street engine. If you do have vacuum advance, do you know how many degrees it is pulling? They do differ and also can pull specific based on the vacuum signal.

- What is the RPM that your 36 Total is all in? 3,000 RPM's is generally a good number to shoot for.

- I take it the AC was added to your non-AC car? The condensor could be blocking low speed air flow, but from my understanding, a condensor also throws off a lot of heat which could be going directly into the radiator core adding to the heating issues. "During the conversion process, the AC condenser is able to generate a considerable amount of heat, which can affect the overall engine temperature enough to cause overheating."

Is the condensor spaced away from the radiator core or attached right to it?

- Does your RPM increase when the AC is activated? I am not an AC guy, but I am almost 100% positive that idle speed is supposed to increase with AC on.

- 1 1/4" tubes provide more surface area for cooling over the 1" of equal size. More rows are not necessarily the answer, but you might think so. Sometimes more rows can block air flow.

- Basics, 50/50 coolant? Have you tried any products like Water Wetter? If you still have the heater, have you tried putting the heater/fan on max to see if this will help cool engine temps? This can be a good test that indicates you need more radiator core for cooling. Underhood insulation can hold in a lot heat. Removing it can help. Another reason some use the RA hood insert, not for the RA effect, but to let underhood heat out and also draw in cooler air.

[chrisp]

What is your AFR @ idle & cruise ?

[Scott65]

What is your timing at idle? If the Holley is controlling it, you can add(yes add) some right at idle speed. I know of myself and one other here running 30 or a little more. I know of another member here that found improvements in idle temps going from 20 to 25. It's easy, and free to try.

[sjdiesel]

50/50 coolant
Condenser is in front of the radiator. Around 1/2” gap between it and the radiator.
Idle does increase when AC kick on.
AFR at idle is set at 13.8 and 14.2 at cruise if I remembered correctly. Seems Pretty steady
Idles at about 20* timing. 36 all in at 3k. I set it to 42 at light cruise. I may bump the timing up a little at idle.

I’m going to swap out my fan clutch tomorrow. It has a lifetime warranty so I figured what the hell. I feel like I don’t hear the fan howl like I use to.

[leeklm]

'I don’t know the distance between the plate and pump because I didn’t put it together. A reputable Pontiac engine builder did. I assume it is correct. Although I have thought about pulling the pump off and double checking for my own peace of mind"

Unless you specifically asked for the builder to check and adjust the plate clearance, there is a high likelihood the pump was bolted on "as is". On a buddies 66, the plate gap was very wide with the flow cooler pump. Was something like 1/4"

Sent from my SM-G965U using Tapatalk

[sjdiesel]

Originally Posted by leeklm

Unless you specifically asked for the builder to check and adjust the plate clearance, there is a high likelihood the pump was bolted on "as is". On a buddies 66, the plate gap was very wide with the flow cooler pump. Was something like 1/4"

Sent from my SM-G965U using Tapatalk

Funny you say that. My curiosity got the best of me the other day so I pulled the pump and checked the clearance. Sure enough there was over 1/4” gap between the plate and the impeller. I massaged the plate some and now the gap is around .030-.040. Haven’t really driven the car much in the heat yet so we will see if that made a difference.

I plan on ordering the Cold Case’s HO/SD radiator for an AC car towards the end of this month. I will cut and modify my core support to accommodate the bigger radiator. I want this cooling thing fixed once and for all. I’ve spent too much money on this car to not be able to drive it whenever I want.