Radiator confusion = Is it Possible the l6 250 Rad is the same as the 350?

[Yamariv]

Hey guys,

I'm currently doing a full service on my cooling system to get it ready before the hot weather hits.. I did a flush today and was planning on bringing in my original I6 250 rad into the rad shop to get it steam cleaned and pressure tested. My Dad had a good point suggesting I see what a bigger new rad would cost instead of dumping money into the old one. I was thinking of going bigger so that I've already got that angle covered if I decide to go with a SBC in the future.

I called my parts guy and he said his system shows the L6 250's rad the same as the 350 SBC for the 1971 year. I also checked Rock Auto and they suggest the exact same rads as replacements for the L6 and the 350 as well.

Is this possible??

[LockDoc]

Originally Posted by Yamariv

Hey guys,

I'm currently doing a full service on my cooling system to get it ready before the hot weather hits.. I did a flush today and was planning on bringing in my original I6 250 rad into the rad shop to get it steam cleaned and pressure tested. My Dad had a good point suggesting I see what a bigger new rad would cost instead of dumping money into the old one. I was thinking of going bigger so that I've already got that angle covered if I decide to go with a SBC in the future.

I called my parts guy and he said his system shows the L6 250's rad the same as the 350 SBC for the 1971 year. I also checked Rock Auto and they suggest the exact same rads as replacements for the L6 and the 350 as well.

Is this possible??

Anything is possible but the stock radiators are not the same. I can't say specifically on the '71 but all of the I-6 trucks I have owned had 2 core radiators, all small blocks had the 3 core, and all big blocks had the four core. Maybe there were exceptions but not to my knowledge.

Maybe the newer technology makes it possible to use the thinner radiators as a replacement, or maybe they only make 3 & 4 core replacement radiators. Then it wouldn't be a problem. I would check on that.....

LockDoc
'

[57taskforce]

Didn’t ac trucks have 4 rows too? Mine is a small block 4 speed ac truck and had an original Harrison copper/brass 4 row in it with a fan clutch when I bought it…

[mr.mud1]

i can't say if a 6 cylinder truck and a 350 rad are the same but i wouldn't be surprised if that's,in fact the case.if they are the same,no matter then but if there is any differance and a small block may be in your future,go ahead and do it now.i've had a bunch of these trucks but never a 6 cylinder?i do know the 72 big block A/C truck i have now,built at the Fremont,Ca plant,has a new rad i built.it was and is 3 cores,in tanks and saddles that would've accomodated a 4 core,core.i almost ordered a 4 but figured if 3 cores is what it came with and it lived in California and survived,it would be fine here.this is a 1 owner,75,000 mile truck in storage for 25 years til i bought it.i can't imagine anybody ever fooled with it?i did check the build sheet but there's nothing noted for the rad,only the shroud and hoses.i'll have to check the spid when i get out to the shop.

[Steeveedee]

It the radiator is the same square footage for the I6 or the V8, two rows would likely work, if you don't run AC. But I wouldn't do it. I can vouch for the fact that a two row radiator is marginal for a 400 SBC with AC. Chevrolet tried to save money on big cars and put 2 row radiators in many. We had several of them sitting waiting for engines after they roasted, less than one year old. No savings there!

[Yamariv]

Originally Posted by mr.mud1

i can't say if a 6 cylinder truck and a 350 rad are the same but i wouldn't be surprised if that's,in fact the case.if they are the same,no matter then but if there is any differance and a small block may be in your future,go ahead and do it now.i've had a bunch of these trucks but never a 6 cylinder?i do know the 72 big block A/C truck i have now,built at the Fremont,Ca plant,has a new rad i built.it was and is 3 cores,in tanks and saddles that would've accomodated a 4 core,core.i almost ordered a 4 but figured if 3 cores is what it came with and it lived in California and survived,it would be fine here.this is a 1 owner,75,000 mile truck in storage for 25 years til i bought it.i can't imagine anybody ever fooled with it?i did check the build sheet but there's nothing noted for the rad,only the shroud and hoses.i'll have to check the spid when i get out to the shop.

Ok, looks like I found a stock 3 core locally! Question, in your pic there are holes for a trans cooler. How does the trans cooler work, does it use up some inner rad space or can I just block those holes off and use the full rad for engine cooling as I have a 3 speed standard.

[Steeveedee]

You don't need to do anything, but you can plug the bottom hole if ATF drips out. It takes a 5/16 inverted flare b-nut thread plug. Those systems are isolated from each other.

[Yamariv]

Originally Posted by Steeveedee

You don't need to do anything, but you can plug the bottom hole if ATF drips out. It takes a 5/16 inverted flare b-nut thread plug. Those systems are isolated from each other.

Oh interesting that they isolated, makes sense! Am I going to loose any real cooling capacity because it's there, should I try to find one without the cooler or is the difference minimal?

If I plug the holes, just metal on metal or should I use teflon?

[mr.mud1]

Originally Posted by Yamariv

Ok, looks like I found a stock 3 core locally! Question, in your pic there are holes for a trans cooler. How does the trans cooler work, does it use up some inner rad space or can I just block those holes off and use the full rad for engine cooling as I have a 3 speed standard.

yes sir,already answered but plug them if you want to,nothing is going to happen.the cooler is in that end of the tank and as said,coolant is isolated from ATF so nothing to worry about.good to go.

[LockDoc]

Originally Posted by 57taskforce

Didn’t ac trucks have 4 rows too? Mine is a small block 4 speed ac truck and had an original Harrison copper/brass 4 row in it with a fan clutch when I bought it…

Very possible, and that is why I included the disclaimer. I have never owned a factory A/C truck except for a couple of parts trucks.

I will see if I can remember to take pictures of the 3 different radiators this morning and post them.

LockDoc

[Yamariv]

Interesting, thanks guys!!

Anyone know of a quality USA made repro for a decent price? I'd need the mounting brackets for the bigger rad too I assume..

Lastly, how do you tell how many cores are in the rad?

[mr.mud1]

Originally Posted by Yamariv

Interesting, thanks guys!!

Anyone know of a quality USA made repro for a decent price? I'd need the mounting brackets for the bigger rad too I assume..

Lastly, how do you tell how many cores are in the rad?

you can usually see the rows of tubes.the picture i put on of my 3 core rad core with the tanks off,is plain as day,count the rows of tubes.how many rows in the core you have now?probably 2?i get my brass/copper cores from Spectra-Premium,built in Quebec.any local rad shop,if they care to help should be able to get a core and build you a rad.send your tanks to me,i'll build you one but no reason why you couldn't get one done locally or close by if you have an old fashioned rad shop to help.the last time i think i looked on Rock Auto,the dimensions of the rad,and rows of tubes was listed in the rad description,shouldn't be hard to figure out what a 6 cylinder rad is compared to a 350?personally i stay away from aluminum rads,lots of guys use them and have no trouble but as long as i can get brass/copper cores,i'll continue to do them the old fashioned way.take care.Greg

[mr.mud1]

Originally Posted by mr.mud1

you can usually see the rows of tubes.the picture i put on of my 3 core rad core with the tanks off,is plain as day,count the rows of tubes.how many rows in the core you have now?probably 2?i get my brass/copper cores from Spectra-Premium,built in Quebec.any local rad shop,if they care to help should be able to get a core and build you a rad.send your tanks to me,i'll build you one but no reason why you couldn't get one done locally or close by if you have an old fashioned rad shop to help.the last time i think i looked on Rock Auto,the dimensions of the rad,and rows of tubes was listed in the rad description,shouldn't be hard to figure out what a 6 cylinder rad is compared to a 350?personally i stay away from aluminum rads,lots of guys use them and have no trouble but as long as i can get brass/copper cores,i'll continue to do them the old fashioned way.take care.Greg

hi,i just went and looked at Rock Auto cause i was curious.they only show aluminum rads now,but the same part number for a 2 row 6 cylinder and a 350,core measures 28 1/4 X 17 and they show a 3 row for the 6 and the same rad for a 350 . hopefully that's a help?

[Yamariv]

Ok, so I spent all morning calling around and researching options. Looks like I'm looking at $600 to get my 2 core rad re-cored and made into a 3 core. Man that's pricey!!

I've been looking at a pretty much direct replacement aluminum rad on ebay from Champion Radiator. I think they are US made, anyone have any experience with them?

Here's the listing:

http://www.ebay.com/itm/165232541207...o0OBh#shpCntId

[Steeveedee]

I bought a Cold Case aluminum radiator a few years ago. I'm happy with it.

[LockDoc]

-
Here are the differences in the 3 stock radiators. Very easy to tell. You can also remove the radiator cap and look inside with a good light and count the tubes. A few may have the trans oil cooler in the way but I think you can still see over it.

2 core on the left, 3 core in the middle and 4 core on the right. The 2 core and 3 core use the same lower saddles and upper hold down brackets. 4 core saddles and brackets are different. The 2 core radiator is also narrower in width. that is why there are two sets of holes in the core support.

LockDoc

[MikeB]

Originally Posted by Yamariv

Ok, so I spent all morning calling around and researching options. Looks like I'm looking at $600 to get my 2 core rad re-cored and made into a 3 core. Man that's pricey!!

I installed an aftermarket aluminum rad in my 82 C10. I bought it at O'Reilly Auto parts and it had a lifetime warranty. I drove that truck another 5 years in Texas summers w/o any problems at all. I think the brand name was Spectra, and back in 2015 it cost around $125.

[72SB]

fewer but larger (read 2 row vs 4) are better cooling. 2 row with 1 1/4" to 1 1/2" tube is better than 4 rows of smaller tube.

I have a Cold Case 2 row (1 1/4" tube) in a 67 Camaro, nice radiator. I would not hesitate to buy one for my C10 when needed....

['68OrangeSunshine]

Originally Posted by Yamariv

Hey guys,

I'm currently doing a full service on my cooling system to get it ready before the hot weather hits.. I did a flush today and was planning on bringing in my original I6 250 rad into the rad shop to get it steam cleaned and pressure tested. My Dad had a good point suggesting I see what a bigger new rad would cost instead of dumping money into the old one. I was thinking of going bigger so that I've already got that angle covered if I decide to go with a SBC in the future.

I called my parts guy and he said his system shows the L6 250's rad the same as the 350 SBC for the 1971 year. I also checked Rock Auto and they suggest the exact same rads as replacements for the L6 and the 350 as well.

Is this possible??

No. The OEM style L6 radiators were about 4'' narrower across the front. That's why there are duplicate sets of frame nuts in the radiator bulkhead about 4'' apart on the passenger side.
The P/Ns show the same piece now because you could not get an L6-0nly radiator to save your life. They just quit making them.
You can only get the V8 radiators. Good if you live in high heat country. Much more cooling surface.

[Steeveedee]

That's why I was talking about "square footage" earlier. Did a 292 have the narrower radiator? I'd expect maybe it was bigger?

['68OrangeSunshine]

Originally Posted by Steeveedee

That's why I was talking about "square footage" earlier. Did a 292 have the narrower radiator? I'd expect maybe it was bigger?

Yes. It had a 2-Core, Narrow radiator. Not an issue on a fleet truck in Southern California. The original dealer was Felix Chevrolet in Downtown LA.
The thin design of the L6 -- that is, all the space between the fenderskirts as opposed to a V8's width, aids in air cooling.
The L25 292 has a deeper oil pan, taking 6 quarts, not 5. More oil volume aids cooling.
I think 250s and 292s got the same radiator. But I'm not sure.
I added a big FlexFan in Yuma in 1977. I also rebuilt that year. Later, I had to go with a V8 radiator [w/ATF plumbing] because that was the only game in town. Quite pleased with the larger volume of a 3-tier wider radiator.
My Stepside just purrs at 180* all day long in summer heat -- when thankfully the Snowbirds have gone home.

[Yamariv]

Originally Posted by '68OrangeSunshine

No. The OEM style L6 radiators were about 4'' narrower across the front. That's why there are duplicate sets of frame nuts in the radiator bulkhead about 4'' apart on the passenger side.
The P/Ns show the same piece now because you could not get an L6-0nly radiator to save your life. They just quit making them.
You can only get the V8 radiators. Good if you live in high heat country. Much more cooling surface.

This is correct! After all morning researching rads and measuring the 3 core vs 2 core..my stock 2 core is shorter in length but just as tall as the 3 core for the SBC's. To mount, all I'll have to do is move one of my top rad clamps over a few inches to the other factory holes.

When I looked at my L6 2 core rad closer, it actually doesn't sit centered in the rad support opening hole cause its smaller. It's actually a few inches over to one side. Kinda interesting! The bigger 3 core should fill the hole fully now.

[CKfan]

Originally Posted by Yamariv

This is correct! After all morning researching rads and measuring the 3 core vs 2 core..my stock 2 core is shorter in length but just as tall as the 3 core for the SBC's. To mount, all I'll have to do is move one of my top rad clamps over a few inches to the other factory holes.

When I looked at my L6 2 core rad closer, it actually doesn't sit centered in the rad support opening hole cause its smaller. It's actually a few inches over to one side. Kinda interesting! The bigger 3 core should fill the hole fully now.

=Photo of my 292 Inline 6 with my original "heavy duty" 3 row rad and shows the wider mounting point in the photo.

The rad shop is piecing my original back together using one of the 3 core rads I had sitting around. They are only going to use my original passenger side tank (has Harrison and the tags on it).

[mike16]

There was a similar discussion on another forum. I don't remember the details but what I do recall vaguely is that there was only 1.5 quarts difference between a standard six cooling system and a 4 core heavy-duty big block cooling system.

[CKfan]

I get more confused every time I research this radiator business. My inline-6 292 manual trans (69 K10) had the heavy duty radiator listed on the SPID as option V01.

I am assuming from what I have read, it is the same as the big block units but being 50 + years old it may have been swapped out at some point. Rad shop said mine was repaired with JB weld, solder and a few other things on too many times to save. I have a couple 3 row inposters on standby while I search for a 4 row "correct??" replacement.