Big Block Swap Rad /6 engine

[4speedjim]

The weathers finally broke and im back in the barn. Yea! So my /6 was overheating, cooling systems PACKED with hard water deposits. Straight CLR, straight white Vinegar and a combo of both over last fall (3 months) helped but wasnt a fix. Dont believe anyone that tells ya 11 minutes is too long or all you need. 3 months wasnt enough, did no damage.
Im still collecting parts for the 400 stroker and decided to slide the BB radiator in with 1/4" larger in & outputs and running the /6 over the summer. The new Alum 3 row has 1/4 larger in & output and Im looking for adapters. 1.25 to 1.5" & 1.5 to 1.75. I found Spectrum, but theyre descriptions say theyre for Spectrum hoses. Im not looking for $250 rad hoses to get me through the summer and other than a few /6 time slips to compare with the 470 out of curiosity. Im not racing it, so Im not concerned about oiling or "coolanting" the track. Any of you have a suggestion? I looked for exhaust adapters and found a few 1.5 to 1.75 but no luck with the 1.25 ro 1.5 size. I considered rodding the solid, quality 2 row OEM replacement rad, but there is no rad shops in my corner of Western NY. I considered Muriatic acid to clean the cooling system better, but decided to just drop the BB rad in instead. Its just to get me through the summer so I can take the grandkids for ice cream and sports practices and believe it or not, Im out of ideas and looking for help.

 

[Aspen500]

Not sure if anything here would work but they have some stepped diameter radiator hoses. One is 1.25" to 1.5". Part way down the page. Maybe use that and a pipe between the adapter and the stock hose?
Street Rod Radiator Hoses - Free Shipping @ Speedway Motors

 

[4speedjim]

That exactly what I was looking for! Thanks Aspen500! Out of desperation I measured a couple rigid hose extenders that dont stay on our vacuum like they where designed to. The wife will not be happy that they have disappeared! These "Inserts" will reinforce the 1.25" & 1.50" hoses at the clamp connections.

 

[jasperjacko]

I wouldn't run that dirty old motor through that new radiator. Pull the freeze plugs in the bottom end and clean it out.

 

[jasperjacko]

Or just run it and clean it before the new engine goes in.

 

[Aspen500]

I learned when building my car, to "think out of the box" when looking for non-stock pieces. Have some Speedway parts on my car that are technically street rod parts, for example. Also never overlook stock parts from other makes when building something other than a restoration. I've got a little Ford, a little Audi, some Kia/Hyundai (hose and wire harness holders/clips), etc......

 

[jasperjacko]

KKK-Kia?

 

[Oldiron440]

Hey when I swapped my 440 into the Volare I use a 360 rad and was able to get colars that slipped over the lower rad inlet then you slid the hose form the 440 on to it, clamp it, done and it worked.

 

[Oldiron440]

A hose reduction if you will.

 

[BudW]

4speedJim,
Did your /6 come with A/C?

The reason I ask is most /6's and 318's without A/C came with 18” radiators, whereas most everything else (FMJ wise) comes with 26” radiators.

I’m not sure if you can bolt the wider radiator in place of the smaller one or not (without drilling holes) – but if you can, then you have the core support blocking airflow to part of the radiator (if you have the smaller core support brackets, that is), or you would need to perform some creative cutting.

My ’86 5th Ave has the bigger radiator (if you want to call it that, it is still smaller than ones used in early ‘70’s).
My ’77 station wagon has 318 without A/C – so it has the smaller radiator/smaller core support brackets on it. If I was going to install a big block into it – than that would be one more thing to fix, first.

Note: it sounds like we are both gathering parts for similar builds – so we might want to get together and compare notes.
BudW

 

[DCAspen]

22" radiator will bolt right in,most 318 and /6 w air had 22"

 

[BudW]

That might be possible. I need to go measure.

 

[Aspen500]

Just for reference,,,,,,The rad in my car is from a 360 and Glen Ray Radiators here in town put a 3 row core in. Running a clutch fan and shroud with the 500" big block with A/C, Milodon hi-flow water pump and passenger side outlet w.p. housing (440 Source) and the only time the gauge has ever went above half is on a humid 90 degree day, with the A/C cranked, 35 mph up a 1/2 mile long, VERY steep grade. Even then, it wasn't anywhere close to overheating.

 

[7T8 Custom]

Just for reference,,,,,,The rad in my car is from a 360 and Glen Ray Radiators here in town put a 3 row core in. Running a clutch fan and shroud with the 500" big block with A/C, Milodon hi-flow water pump and passenger side outlet w.p. housing (440 Source) and the only time the gauge has ever went above half is on a humid 90 degree day, with the A/C cranked, 35 mph up a 1/2 mile long, VERY steep grade. Even then, it wasn't anywhere close to overheating.

And is it the 22" or the 26" core?

 

[Aspen500]

It's a 26" core.
This was over 20 years ago but I remember they said it was made from the biggest radiator made for an F-body. I assume that would be a 360 with A/C(?) They supplied the donor radiator. Best part is, they're Mopar people. Same place that makes the repop BB and Hemi rads and P.S. coolers with or without date coding. Only radiator shop in the whole city and they are good, great people up there. Probably why they've been in business for almost 70 years. OK, enough with the advertisement, lol.
I changed the original yoke panels for the 26" ones. My car was originally a 225 without A/C and had a tiny little 18" radiator with the wide side brackets.

 

[BudW]

My ’77 wagon, 318 2-bbl without A/C, also has an 18” radiator.
The distance between bolt holes are 24”.

For a person to fit anything wider in it (26” radiator), one would have to replace the two core support uprights OR do some creative cutting to get the bigger radiator to fit, unrestricted.

I plan on putting A/C on my wagon, so I’m already planning on replacing both core support uprights (as well as a possibility of a big block w/5-speed).


On a different note: the ’72-93 Dodge pickup radiator assembly (or “core”) will fit our cars.
Some of the older pickups (of the above year series) have different brackets – but most have the same end brackets that FMJ's use. If you have an FMJ with the 26” core, and a pickup radiator with different brackets - then a radiator shop can swap the brackets pretty easily (they are only soldered on).
Many pickup radiators came factory with 3 and 4 row cores in them (440 with A/C, for example).

Most car brackets (ABC-bodies) brackets are different from FMJ. Not sure about R-body brackets.

The core typically is the same with two big differences:
- With automatic transmission cooler (if using an automatic, that is).
- Also, watch neck placement on both top and lower tanks. I have seen all 4 combination of neck placements (Left Upper/Right Lower, Left Upper/Left Lower, Right Upper/Right Lower and Right Upper/Left Lower) on the pickup radiators – depending on year, engine size and A/C (which is handy when installing a big block into an FMJ).


I have heard nothing but good things from Glen-Ray Radiators – except not the cheapest ones out there (if looking for a numbers matching exact replacement).

I’d love to get my hands on a couple of their repop external transmission coolers (which are much better than the factory FM police versions) – but at $500 (plus shipping) – I just can’t justify the cost.
BudW