So I'm now finding out that the fitment with LS1 fans on a stock 3rd gen radiator and shroud is really bad. So I got to thinking maybe I could try an LS1 shroud, but then remembered the LS1 radiators are not as long as the 3rd gen radiators, so the shroud probably wouldn't fit my radiator. So I got to thinking again, if I get a radiator from an LS1, A) will it fit easily, and B) will I need to do that heater hose mod with the waterpump nipple or something else? I thought I read that the LS1 had its steam release built into the radiator? Can someone enlighten me on either my theory about the LS1 radiator, or how they got the LS1 fans to fit better on a 3rd gen radiator? Also, would I be able to use the regular LS1 radiator upper and lower hoses with the new radiator? I just bought the V6 upper hose and 7.5L Ford lower hose today (TTA lower hose was discontinued )

your best bet is a LT1 radiator (same length as the 3rd gen) with the mounts for the fans

you will still have to modify a 3rd gen upper fan shroud to hold the radiator in place. I used a single fan piece and just chopped it up to clear the ls1 fans.

I also used all ls1 style hoses for my swap

-jason

I went down this route in my swap

best option is

3rd gen radiator, 3rd gen fans and 3rd gen upper rad mount.

FYI

The 3rd gen elec fan motor and connector pigtails are exactly same as LS1 and probabaly LT1 too.


I know u said that one of ur 3rd gen fans motots were not working....swap the LS1 motors in.


The next bet is if u already have a LS1 radiator and fan and make it work. I wouldnt go out and buy one.

The LS1 is a little less wide. so there will be small gaps on the sides. but fits good.

you will have to leave the upper rad bracket off....and just bend a couple aluminium tabs to hold the ls1 rad/fan up top. Try conduit hanger at HD.

If you do decide to go with the LS1 Rad / Hoses I will buy those hoses you just bought. I am gonna be using the stock 3rd gen rad with the stock dual electric fans.

LS1 rad here. Fits fine even with the fan assembly and a/c condensor. AND the stock upper radiator support.

The LS1 rad is shorter. You have to cut off a locating nipple on the bottom, but thats it. Then...you put the rad over towards the passenger side so that it sits in the factory rubber isolators. You re-locate the drivers side isolators so they match up. Just need to drill a little hole for the isolator nipple.

You will have a gap on the drivers side, but so far it hasnt effected my cooling at all. I do plan to block it off with some insulation foam or an alum shield of some sort. But it hasnt caused me any issues.

The top support will fit. You just gotta trim it alittle here and there. Mine held strong even after my accident in my 87. Rad never moved.

I think I had to clearance the fans just a TINY bit to clear the steering box. Just a little shaving with a knife and it fits fine. Your experience may vary depending where you place the rad and your car and all.



You can see in this picture where I drilled a new hole for the rubber isolator nipple. Its a couple inches towards the passenger side.



Just a couple others from my 87...


Here's the gap on the drivers side. HOWEVER...its not that bad. See that core support? Its bent over due to a previous accident before I got it. Its no where near that bad on my 86.



Finally, here's where I had to do a little trimming. Cant really see the trimming in this pic, but its more trimming to get it to fit. Once its in, there is plenty of space, you just gotta make some room while putting it all in. Self explanitory once you get into it.



Also...if you arent using the 4th gen a/c condensor, you can probably shove it over to the passenger side more if you want...but I see no reason for that.

You cant really go wrong. But Liked the 4th gen rad due to how the fans and condensor fit. Also it had the steam nipple, and allowed me to use the 4th gen rad hoses..which just fit better for me.


J.

Ok so with an LS1 radiator, you don't need the nipple drilled and tapped into the top of the waterpump?

Correct. Another huge plus for the LS1 rad...atleast if you already have one sitting around in a donor car.

In my first picture, look under the radiator cap. The first hose is the overflow. The second is the steam line. It runs over to the crossover pipe infront of the intake. Simple as that.

J.

I've heard of folks using the 3rdgen radiator and LS1 fans/shroud. The shroud doesn't cover the whole radiator, but that's ok. It's purpose is to help pull air through - and it does that just fine with a little gap left.

I've got 3rd gen radiator, fans, and no shroud - and cool great.

Nick,

Dont use the stock LS1 rad if your running an iron block motor.

The LS1 rad is a single core and a fair bit smaller then the LT1 rad.

The small rad isnt up to the task of the iron block. Theres alot of people having problems with iron blocks overheating cause the rad cant keep the coolant temp down.

I had the issue with my iroc-z when i had the 6.0 in it.

If you run a LT1 rad w/ LT1 fans you wont have issues, it still has a steam nipple on it, and the fans plug is the same as the LS1 fan plug.

Had no problems with my 6.0L in my t/a with the LT1 rad.

i run 4th gen rad, fans and an lt1 shroud to hold it all in.
looks like stock.

the ls1 rad is a lil thinner than the lt1. 15/16" vs 1 or 1 1/4 i think it is.
ive ran both and seen no benefit of the thicker version, but run it for piece of mind. it was also cheaper at the parts store by 100 bucks.

Hmm...didnt know that about the LT rads. Thought they were the same. More cooling and cheaper...doesnt sound like you can go wrong!

Ill have to look into that when I eventually need a new rad.

J.

That's cool that the LT1 fan setup is best, one thing I can keep when the aluminum block goes in. I'm running the LT1 radiator with condensor tabs cut off, modified LT1 Shroud, LT1 Fans, thirdgen condensor. Have a picture of the shroud but its a really old pic from years ago:

Weird that you didnt see a difference.

My iroc-z cruised at 220* and when i slowed down it would overheat.

Exact same motor in my trans am, only difference is LT1 rad, and the trans am front end has much less airflow to rad, i cruis at 180* and dont cross 190* in traffic.

Man, I seriously can't believe that you're not seeing any overheating issues with that kind of gap... When I yanked the A/C out of my car, I had a smaller gap than that (although on each side of the radiator), & just about every time the ambient temp climbed, I knew that I could just about expect a 10-minute "pause" with my hood up on the side of the road during my drive home...

I'm pretty confident that once you block it off (and air has to go through the radiator instead of around it), you'll see a noticeable difference in coolant temp.

I ran it that way since I swapped the motor in...on both cars. No heat issues in the 87. 160 degree t-stat, and the fans came on accordingly. Never got about 170 even sitting in traffic. Made the 8 hours drive from PA to OBX, NC without issue.

My 86 has to have the fan turn ons tweaked. Forgot to have my tuner do that for me. But even still, I never get above 190 even in extreme summer traffic type of heat.

Dont forget...that picture is without the condensor. Its a little decieving. Plus the core support is bent WAY over. The top spot welds are broken even.

I never saw an issue. The front air dam sorta pushes the air right up to the rad, instead of the air hitting it from straight on. Maybe that helps?

Someday Ill block the gaps. But it just hasnt ever been an issue.

J.

Well, I got it figured out I think. I have zipties holding the fans to the radiator and trimmed down the shroud, and got them fans wired up and loomed too. It looks pretty darn good, I'm gonna post pics later tonight in my swap thread.

regular zipties?
i have found that drilling some holes and using a transmission cooler "ziptie" holds them the best.
i had a chevy truck i put a set of lt1 fans on 10 years ago and its still kicken with a buddy of mine i sold it to.

Yep, regular zipties. They're black so its hard to see them I will post up pictures later, I'm stuck on the new Call of Duty right now LOL

Those ls1 fans and shroud on 3rdgen radiator? Looks really nice! Trimmed 3rdgen shroud too? I may be doing some eBay hunting...that's clean.

Running an LT1 radiator, a/c condensor, fans and shroud on mine

of course it is an LT1 though in the car but here's some pics



I tried to center it as much as I could, it's really close

Ya Jon, its my stock shroud and radiator, just used a couple zipties thru the radiator and trimmed off the back side of the shroud I used a table grinder, if that's what its called. Its a big grinding wheel on a table much like a table saw, helps make the cut clean and even.

I paid an extra $75 for the radiator fans when I bought my engine/trans. Since my car was a mechanical fan originally, I didn't have a top radiator mount I could use, found a 3rd gen upper mount (new) on eBay. Looking at the two, I finally gave up on the idea of kludging the two together and picked up a pair of 3rd gen electric fans. So, (once I get to that point) I'll be using the 3rd gen radiator (brass tanks - had it gone through by a radiator shop), and dual electric 3rd gen fans.

Maybe I'll be able to use the 2000 fans on the '57. . .

Those fans look really good in there! My bird came with dual fans so I just reused them with a 3rdgen rad.