79 400ci vs 350ci radiator size, same?

[Joe T]

I bought a 79 jimmy with a 400 in it (according to the previous owner). The VIN is for an original 350.

I am planning to go through the truck mechanically soon.

Should I put attention to the radiator as I am willing to bet it was never swapped.

I have a shroud out of a 78 I believe 454 and wondering if I need to use it and swap radiators. If not I’ll just hang onto it.

 

[Arkansas_V8]

Should be No difference between the radiators.

 

[Craig 85]

How many rows does it have? IIRC (circa 1992) my '77 K5 had a 4 row radiator with my 400, AT & A/C.

 

[77 K20]

I was under the impression that with the 400 you got a 4 row radiator which was the same as a 454. That was the case anyway for my '78 K5, '77 K20, '78 K10 and my dads '79 K15. (all 400 equipped)

 

[Rusty Nail]

Good enough for me!

 

[Arkansas_V8]

How many rows does it have? IIRC (circa 1992) my '77 K5 had a 4 row radiator with my 400, AT & A/C.

I was under the impression that with the 400 you got a 4 row radiator which was the same as a 454. That was the case anyway for my '78 K5, '77 K20, '78 K10 and my dads '79 K15. (all 400 equipped)

So I was wrong. Not the first, nor the last time.

My two 400 motor trucks had plain old 350 radiators. But no ac. Were not 4 core.

 

[75gmck25]

Take a look at the listings in Rock Auto and LMC truck, which have a good list of available sizes for each year. IIRC, there are two different vertical sizes (17" and 19"), and they come as 2, 3 and 4 row radiators. In general, you can use any of them that are listed for your year of truck, but you need the upper and lower brackets with the right rubber inserts to fit the form factor of the radiator.

I don't think the shrouds are unique to the radiator size, since they bolt on separately. However, the shroud has to be matched to the fan size and configuration. Most of these trucks used a temperature sensitive fan clutch, which is sized so that it extends the correct distance into the shroud. My truck had the HD cooling option, so it has a 7 (I think) blade metal fan and HD fan clutch. My shroud is one piece, but I've seen other trucks with a two piece shroud.

I bought a Champion 3 row aluminum radiator to replace the 3 row stock radiator in my '75, and it works much better than the old radiator. I looked at seveal brands of aluminum radiator, and the Champion was the least expensive choice from a major retailer.

Bruce

 

[Arkansas_V8]

Hell just do what I did, radiator for a diesel(huge 4 core). Had to trim mounting brackets(this came with a regular 4 core) other than that fit fine, and two 12" electric fans.

I can idle up the rocks, or rap it out in the mud, and not once overheated.

You must be registered for see images attach

 

[MikeB]

My 82 C10 came with a 250-six and the smallest radiator. Seems like it was also used with the 305 and 350, at least the ones w/o A/C. But since it was old and I needed the auto trans cooler, I replaced it with an aluminum one (the same size). Anyway, it has worked just fine with my 355 for 4 years now, even in 100 degrees temps at stop lights. Hoping it will still work OK when/if I add A/C.

BTW, that's a light duty thermal fan clutch that I got for free. Thought I would eventually have to replace it with an HD version.

Here's the radiator that I used. You can see that the shroud is made specifically to fit this size.

You must be registered for see images

You must be registered for see images

Below is a taller radiator (19"?) that I ended up not using, but I forget why. As mentioned above, the top mounting brackets are different for these two radiators.

You must be registered for see images

 

[Arkansas_V8]

My 82 C10 came with a 250-six and the smallest radiator. Seems like it was also used with the 305 and 350, at least the ones w/o A/C. But since it was old and I needed the auto trans cooler, I replaced it with an aluminum one (the same size). Anyway, it has worked just fine with my 355 for 4 years now, even in 100 degrees temps at stop lights. Hoping it will still work OK when/if I add A/C.

Here's the one that I used. You can see that the shroud is made specifically to fit this size.

You must be registered for see images

You must be registered for see images

Below is a taller radiator (19"?) that I ended up not using, but I forget why. As mentioned above, the top mounting brackets are different for these two radiators.

You must be registered for see images

Very nice.

But I would warm up on the rocks crawling around, or in the mud spinning the rpms up with something that small, even with my stock 4 core.

What I use now keeps me around 150 doing both.

Two different worlds.

I do daily this, atleast I did, and will after surgery.

It's very diverse in what it can do.

I built it to be good at everything, and great at nothing.

 

[MikeB]

150 degrees? That's not anywhere near hot enough to boil off, or at least evaporate, moisture in the crankcase so it doesn't contaminate the oil. Also, I don't think your pistons and rings will seal as well at lower temps.

And from what I've read, maximum efficiency is at 185 degrees. Below is an excerpt from one article, but you can find many more, some of which recommend even 200-210 degrees.

"Internal combustion engines operate most efficiently at relatively high temperatures, typically above 80°C - 85°C (176°F - 185°F). Wear on the moving parts is reduced and thermal efficiency is increased by operating at this temperature.

Lower engine temperatures result in inefficient combustion which causes increased fuel consumption, and increased wear with consequent reduced engine life."

 

[Arkansas_V8]

150 degrees? That's not anywhere near hot enough to boil off, or at least evaporate, moisture in the crankcase so it doesn't contaminate the oil. Also, I don't think your pistons and rings will seal as well at lower temps.

And from what I've read, maximum efficiency is at 185 degrees. Below is an excerpt from one article, but you can find many more, some of which recommend even 200-210 degrees.

"Internal combustion engines operate most efficiently at relatively high temperatures, typically above 80°C - 85°C (176°F - 185°F). Wear on the moving parts is reduced and thermal efficiency is increased by operating at this temperature.

Lower engine temperatures result in inefficient combustion which causes increased fuel consumption, and increased wear with consequent reduced engine life."

I highly doubt this gauge is 100% accurate. I dont run the fans all the time(dont need to at all). Ment to say 150° all day if wanted.


Fuel efficiency I could care less. I blow no smoke, oil always comes out clean.

Point was- what I have works phenomenally well.

 

[Joe T]

Its got a 350 Vin. Came with these aluminum heads and intake. Mild cam too.

No idea about this radiator and shroud. 1979 stuff, guess they didnt care about your fingers if you reached in a little too far.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[Craig 85]

Unfortunately this is the only picture of the shroud in my '79 K15 before I sold it. I'm not sure if you have the correct radiator top plate in your truck. Mine was flush with the top of the core support, but I think my '77 K5 had one similar to your's. The nut-serts in your core support make me think it was like mine. Also, your truck would do better with a clutch fan instead of the fixed blade fan.

The 454 shroud appears to be the same for 73-87. Here's the one in my '85. The top plate would be different for 73-80 trucks. The last picture is the OEM 4 row radiator that came in my truck.

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach