Three different radiators (3 row, 4 row, aluminum) and their operating temps

[Mike]

Hi folks, I have owned my 1970 with a BBC 402 (425hp) for about 12 years now. Originally came with a 3 row and ran about 220 on a hot florida day. Stainless flex fan with no clutch and a 180 stat. When that started leaking I upgraded to a 4 row. Temperature dropped to 200, so a 20 degree drop. I eventually dropped in a 454 with 555hp and temp went up to 205 maybe, not much of a change. Then a year went by and i stabbed in an aluminum radiator from Auto City (bought at the turkey run from their booth) and temp went to 180! Much better. I think if i stuck in a lower stat it might go down a bit since it sits on that 180 regardless of weather. The only caveat is I would not buy the radiator from Auto City again. The guy told me he used the GM factory tooling/molds to build the radiators and it was an exact fit...well that was bullshyte. The physical size was perfect, went right in. Both necks were spot on. But when i connected the tranny lines they both leaked. I backed them out thinking i just did a rookie mistake, threads looked ok, ran them back in...still leaked. Then I went back to basics and got my thread gauge out. The male fitting was not the same as the female in the radiator. If i recall right, one was 16 tpi and one was 18tpi....barely off! So i called the guy and he said "Yeah, didnt you buy the adaptor?" I was peeved. If he had told me the threads were different I would have certainly bought the dang adaptor. Especially since I had already cut my lower radiator hose already and when i put the adaptors on it pushed the lines back, hitting the hose. ARGHHHHHH. Fortunately, i chased the female threads with a tap and they were salvageable. No leaks for the past few years. So I defintely recommend the aluminum radiator. BUT, i would buy it from NPD and not Auto City. They have great glass, but obviously NOT the original GM molds. My buddy has a 1970 Chevelle with 12:1 compression, a radical 107LSA cam and bored 454 (468CI). He also had the identical results as me, runs at 180F on the hottest florida day. But he got his from NPD and the threads were the same as his tranny lines. Be cool amigos!

[Blackhawk]

I'm going to have to check my radiator, I'm running their LS swap radiator but it looks like I just used inverted flare fittings and haven't seen a leak in my limited use of the car. I'll have to pull the upper line on mine and see if there's an inverted flare seat in the opening. Their website shows that the aluminum radiators have a 1/4-18 NPT fitting instead of the stock inverted flare, but it's possible that they changed it at some point.

[Scott S.]

The inverted flare only works if both the male and female fittings are flared. 

Having worked on generators/fire pumps I've had occasion to find mismatched fitting that someone either taped or siliconed to stop a leak that never went away. 

As for the thermostat, I like the 165 degree for city summer driving. Keeps everything below 200 when sitting at the lights. 

Plus it brings down the transmission temp. faster once I get rolling again. 

[Mike]

2 hours ago, Scott S. said:

The inverted flare only works if both the male and female fittings are flared. 

Having worked on generators/fire pumps I've had occasion to find mismatched fitting that someone either taped or siliconed to stop a leak that never went away. 

As for the thermostat, I like the 165 degree for city summer driving. Keeps everything below 200 when sitting at the lights. 

Plus it brings down the transmission temp. faster once I get rolling again. 

I havent thought about the tranny temps. I changed the filter and fluid a few years ago and it was great, no burn. But i also have one of those Derale pans with the tubes in it. Swapping to the 4L80e shortly!

[Mike]

5 hours ago, Blackhawk said:

I'm going to have to check my radiator, I'm running their LS swap radiator but it looks like I just used inverted flare fittings and haven't seen a leak in my limited use of the car. I'll have to pull the upper line on mine and see if there's an inverted flare seat in the opening. Their website shows that the aluminum radiators have a 1/4-18 NPT fitting instead of the stock inverted flare, but it's possible that they changed it at some point.

If you are not leaking i guess i wouldnt worry about it. My stainless tranny lines were new from InLine tube and they said they had the factory fittings. Really not sure if they did, i just assumed so. All i know is the male and female were off by two threads, hence the adaptor. 

 

[DragCat]

I went with the Griffen alum with electric fans 502 crate. I'd have to look up the stat spec but saw an immediate drop in temps. Never cared for the Monte fan shroud anyway 🤣

[Scott S.]

20 hours ago, Mike said:

If you are not leaking i guess i wouldnt worry about it. My stainless tranny lines were new from InLine tube and they said they had the factory fittings. Really not sure if they did, i just assumed so. All i know is the male and female were off by two threads, hence the adaptor. 

 

I've noticed a difference in thread types too.

Maybe different manufacturers, modernized specs, the metric system..... So many factors.

When I had my steel braided fuel line made, I too the fancy in line filter to get the correct threads put on. 

Went to install it, and both the G.M. fuel pump and Edelbrock carb had different threads than the filter. 

I wound up making an adapter at either end to make it work. 

[Scott S.]

20 hours ago, Mike said:

I havent thought about the tranny temps. I changed the filter and fluid a few years ago and it was great, no burn. But i also have one of those Derale pans with the tubes in it. Swapping to the 4L80e shortly!

When I had my 200r4 built, I got the builder to weld a female 1/2" NTP connection to the side of the pan. 

makes a great temp sender outlet as well as a drain. 

[Mike]

On 12/3/2024 at 2:39 PM, Scott S. said:

When I had my 200r4 built, I got the builder to weld a female 1/2" NTP connection to the side of the pan. 

makes a great temp sender outlet as well as a drain. 

Thats a great idea. Im putting in a 4L80 next week. Gonna do that!

[Scott S.]

Some like to put a sender inlet in the cooling lines. Easier, I guess.....

The pan outlet has fewer threaded connections, fewer places to leak.

And there's the question of where the hottest point of the fluid is at.