cj7 258 HD cooling shroud and radiator for a V8 swap offset and dimension case of CRS

So this is specifically about the shrouds and the fan opening offset, I already have a plethra fo radiators to compare and going aftermarket the thickness will be the same I am having a problem chasing down a 6cyl with HD cooling fanshroud to compare to the v8 shroud.


im having one of those nights where i cant remember $hit.

IIRC isnt the offset of the 6 cyl 81-86 hd fan shroud the same as the 304 v8 fan shroud? the water outlets are slightly off so there its not a plug in and play deal.... but i dont have a 6 cyl hd fan shroud (there is also a LD one that IIRC had a smaller opening and less offset.

The HD 6cyl should look like this:
http://www.jeep4x4center.com/product...number=5362539

I want to verify that the opening is roughly 19" around, and the offset is similar to the stock V8 shroud...... it should be the same diameter opening since i believe they came with the 7 blade 17" fan where as the LD had the 6 blade or 5 blade smaller fan and smaller shroud. and at one time id swear in the past i ran a HD 6cyl radiator and shroud with a 304 without any other mods and no issues....... but i cant remember what went on 20 years ago.

my reason for inquiring is the surface area of the 6cyl radiator was always more across the core than the v8 radiator 307-375 +/- cubic inches vs 405-410 cubic inches of core finned surface area. the v8 came with larger tanks but less surface area. i recently came across an aluminium radiator that is spot on dimension wise modeled after the 6cyl hd cooling radiator with smaller tanks but the larger core 408 cubic inches of core surface area. it is down flow design dual 1-1/4" core tubes and solid aluminium.... the thought is that for $200 its a pretty good option to stick in front of a 401 or other 400 cubic inch motor and building a fan shroud is not that much of a pain but if there is a basic shroud that can be swapped in thats close it might be a worthy experiment.


So can a HD cooling 6cyl fan shroud and stock radiator be used ona 304 conversion? does it match up?


And then if it does is there a problem with smaller tanks on the radiator since you are gaining surface area and larger tubes?



If i had a 6cyl shroud or even a couple of pictures witha tape measure in there i could figure alot out. problem is all 3 of my jeeps have 304, 360 and a 401.... and all run stock v8 shrouds with 18" caddy fans stuffed in there.


Bueller??

I haven't ran one since I was a kid. I run a three core rad and it is plenty in the I-6/360.

http://www.cgj.com/shop/radiators/an...adiators/jeep/

looking at the JP3006 it has a larger core surface area and more efficient core than what i have. at 408 cubic inches of surface area its a start. next question is will the smaller tanks effect cooling and how?

The V-8 shroud has the hole for the fan much more centered. If they were the same, they'd be covered by the same P/N. The tanks are just "holding areas", I doubt they affect cooling much at all, although a smaller surface area means less cooling.

Bob
tufcj

Quote:

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Originally Posted by tufcj

The V-8 shroud has the hole for the fan much more centered. If they were the same, they'd be covered by the same P/N. The tanks are just "holding areas", I doubt they affect cooling much at all, although a smaller surface area means less cooling.

Bob
tufcj

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right.

the factory v8 radiators have less core surface area than the 6cyl radiators which is the reason for inquiring about this.

I'm pretty sure the V-8s (at least with the HD cooling) came with a 3 core radiator, the I-6 was a 2 core. Dimensionally they are the same size. I think the fan on the I-6 was a little smaller too.

Bob
tufcj

most the I-6's were 2 core but the core dimensions are larger and tanks smaller, i have a couple of them sitting here. There also was a heavy duty 6 cyl radiator that was 3 core used in AC equipt units also and it had a different fan shroud also. most of them the tubes are smaller on the 6cyl radiators that i have here than the V8 core tubes 3/8 vs 1/2" as far as i can see. but the catch is i dont have the I6 HD fan shroud to figure out the center opening orientation relative to what a V8 would need. the std 6cyl shroud used the smaller fan but the HD i believe shared the fan part number with the v8. but im going to just make one instead.

That link i listed above lists the actual core dimensions on thier replacement radiators and they are pretty much spot on, maybe a hair larger than these old brass V8 and I6 radiators that i have sitting here. i never even gave a 6cyl radiator a second look because the tubes and cores were always so much thinner but if a company is offering the 6cyl core dimensions 17"x24.25" vs the V8 radiator core dimensions of 15"x24.25" with equal thickness cores adn tubes the one with the larger surface area sure seems to appeal more especially to us 401 fans.

Also another interesting fact is the late model radiator support 81-86 is cut deeper than the early models. there appears to be nearly 3/4" more clearance forward top and bottom to allow for thicker tanks.

it appears i can clear a 3-3.25" wide top tank and equally thick lower tank. at 3.25" tick i can accomodate 2 rows of 1-1/4" tubes vs the stand that they offer which is 2 rows of 1".

Im tired of this thing creeping up temp wise on warm days at idle or idle lugging up the slabs. somethings gotta give ....... and i need to give in and finally increase the sureface area of my core to get as much as i can in efficiency. no other tricks seem to give me relief and all the old logic says 1 cubic inch of surface area for each cubic inch of displacement minimum and aluminium can only do so much to help bandaid what i am thinking is an airflow and surface area issue. shoot iknow the fan is drawing enough air it's sucking more than my taurus fan did. from 2'-2.5' in front of the jeep at idle the fan will suction enough air wiggle the t-shirt you are wearing, get any closer and it will pull it towards the grille. and at idle or mild driving i have no issues really but any kind of luggging and heat sink is hard to cool back down


A little history:
So far ive tried the northern cross flow bolt in radiator and the core was really small on that, the be-cool still wasnt happy with the cooling and loosing surface area due to the side tanks. Traded to get them and traded them off. Then i tried the brass exteme cool 4 core radiator with high efficiency tubes and that came close but still would heat soak and climb during long periods of lugging. the manufacturer said it was jsut the nature of the beast. he thought it was air flow since the core lacked surface area and suggested a more aggressive fan as a bandaid. i swapped in the taurus fan on this combo and it worked fairly well better at idle but after a trip where i smoke an alternator and found my self draining batteries pretty darned fast and having to swap out ALOT during that day i decided to carry a spare alternator. the next supprise was when the electric motor in the fan gave up the ghost so i went back to mechanical made a custom shroud and used the Cadillac 472/500 18" high pitch 7 blade fan witha hayden severe duty fan clutch off a buick diesel. sucks some serious air even at idle. still had issues but they were managable this fan cooled just as well as the taurus at idle and i think it may do a little better at 2000-2500 rpm than the taurus did. Then I poked a rather large stick through the radiator two summers ago and in a pinch bought a champion down flow 3 core aluminium radiator for the price $120 it was hard to pass up. it's worked alright, the core is not a high efficiency so the number of tubes are down and the tube thickness is 5/8" so it works out to a core that is about 1.75" thick. in most cases it has no issues keeping me cool but i'm still in search of perfection and that would be a radiator that can really handle lugging the motor with your foot on the brake up a long climb and granite ledge on a 100 degree day without creeping up from 195-200 up to and staying at 220-230 degrees.........

Am i asking too much LOL