Installation information for Radiator #CU730

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SirRobyn0

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Ok so in another thread I made the decision to install a Spectra CU730 in my truck. My truck C20 305 / 700R4, primary uses are DD, hauling and towing 18' open trailer for the farm. Original radiator was copper / brass 3 row 19" tall radiator. I wanted maximum cooling so after deciding the cost of going all aluminum was not going to work out, I went with the Spectra CU730, this radiator is the stock equivalent for 454 W/AC & Max cooling. So it's a very wide 2 core equivalent to at least a 4 core, the 730's core is 2 1/2" wide!!! If you search this site, or the web, you'll find that plenty of guys swap this radiator into their small block trucks as an economical upgrade. I would have actually preferred to keep the cooper / brass but it wasn't practical.

So before deciding to install a 1 1/2" taller, and wider core larger tanked radiator I did some research ahead of time. Most guys seemed to have problems with the mounts, not the metal part but the rubber part as the 2 and 3 row rubbers are to small. So I ordered a set off rubbers for the CU730, so I wouldn't have to modify mine.

My experience. The radiator fits, but it was a much more tricky and required more modification to install than I had expected. First issue I ran into. I was doing the install on the farm, and I'd left my new rubber inserts for the mounts at the shop I manage in town. Driving the 2 hours there and back wasn't practical, so as a stop gap I cut 2 pieces of heater hoses to the length I needed and then cut them in half length wise. That will work for now, but during the work week at the shop I'll pull the top mounts out and slide the proper rubber inserts into place, so that issue is my fault completely and will be remedied shortly. Next issue, the shroud won't fit over the top of the radiator. I know I should have seen that coming, but the most I'd seen was one guy said he "had to trim the shroud a bit, no big deal". Well it's more like you have to cut the entire top of the part of the shroud off that laps over the top of the radiator. I can do that and if done so it's clean and looks good that's fine with me, but I didn't really bring anything from the shop to do that.... So I cut most of the top of the shroud off by scoring it with a razor knife and snapping it, then I took a couple feet of rubber fuel line and slit it length wise and put it along my cut. It looks okish, probably a lot of people would be just fine with it as is. I left a little bit more of the plastic shroud top on purpose so when I'm at work I can cut it and shape it with my angle grinder and / or dremel to look nice and smooth and good. Once the trimming is done the shroud will fully bolt up and sit just like it did before, so this doesn't change the shroud to fan spacing in anyway, so all that should work fine.

Hoses, transmission cooler lines. All that stuff lined up and went together just fine. One more thing then pictures. My old radiator only held about 1 1/4 gallons of coolant, I knew that it had some calcification so I knew it probably wasn't holding as much as it should. The CU730 I just installed took about 3 1/2 gallons of coolant, so it's compacity is definitely much larger.

Pics!

Below: installed and filled!
You must be registered for see images attach


Below picture doesn't really show it, but it does clear the core support without touching, it's a small amount of clearance but should be fine as long as the radiator stays tight, which should not be a problem especially after I get the new rubber mount inserts installed.
You must be registered for see images attach


Below: Top of the shroud. I'm almost a little embarrassed to post this picture, as I thought it looked tacky at the time, but in looking at the picture it's not to bad and will be even better after I trim it properly at work. Will have to be careful not to burn my hands it though! If you look on the right side of the picture see the screw clamp on the A/C line. The truck has had a long standing issue of needed to be recharged each spring. After moving the line around it started hissing there, so I though that clamp on it. Well I guess to good news there is I found that slow leak. So I'll need to replace it this spring.
You must be registered for see images attach


Below, my flavor of choice for Antifreeze, ACDelco classic green. It's available to me though a wholesale supplier (WorldPac) for a really good price $10.50 a gallon. Well that's a very good price around here anyway. plus it's ACDelco! What's better than filling a new radiator in square if ACDelco coolant!
You must be registered for see images attach


I wasn't having any overheating issues, but still I'm looking forward to driving it tomorrow to see if I notice any changes.
 

SirRobyn0

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Well if my trim up on the top part of the fan shroud doesn't work out I've got a couple back up plans now. LMC has the full metal top for the for 454 radiator for $29. And, I just saw a picture of a radiator in squarebody in the web and it looks like the guy just fabed a top plate out of sheet metal. Dang, I might go that route if I'm not happy with my trim up job. It would be super simple with just two bends, 4 bolt holes and a little black spray paint.
 
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75gmck25

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IIRC, on my smaller CU161 radiator, the radiator is sandwiched vertically between the rubber inserts at the bottom and the rubber inserts in the top support. It’s like you put one hand (the rubber support) on top of the radiator and one on the bottom and it does not touch any other metal. It is spaced a small distance from the radiator support so there it no rubbing as the truck vibrates. As long as you keep that isolation it should be fine with a fabricated support.
 

SirRobyn0

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IIRC, on my smaller CU161 radiator, the radiator is sandwiched vertically between the rubber inserts at the bottom and the rubber inserts in the top support. It’s like you put one hand (the rubber support) on top of the radiator and one on the bottom and it does not touch any other metal. It is spaced a small distance from the radiator support so there it no rubbing as the truck vibrates. As long as you keep that isolation it should be fine with a fabricated support.
I actually don't need to fabricate support. My truck has two small separate metal supports on the top it's the plastic shroud wraps around the top of the radiator to the core support. I'm not really sure when they went from the full metal top plate to wrapping the shroud around. It's that part of the shroud that wraps around that is the issue. So really what I'm dealing with is mostly esthetic.

Well drove the truck this morning I want to say that it seemed like the transmission was running 10 - 15F cooler. I've got an external cooler as well, but it goes through the radiator first. I suppose if the coolant in the radiator is cooler, that could translate to cooler trans temps, so that's always a plus!
 

80BrownK10

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Ok so in another thread I made the decision to install a Spectra CU730 in my truck. My truck C20 305 / 700R4, primary uses are DD, hauling and towing 18' open trailer for the farm. Original radiator was copper / brass 3 row 19" tall radiator. I wanted maximum cooling so after deciding the cost of going all aluminum was not going to work out, I went with the Spectra CU730, this radiator is the stock equivalent for 454 W/AC & Max cooling. So it's a very wide 2 core equivalent to at least a 4 core, the 730's core is 2 1/2" wide!!! If you search this site, or the web, you'll find that plenty of guys swap this radiator into their small block trucks as an economical upgrade. I would have actually preferred to keep the cooper / brass but it wasn't practical.

So before deciding to install a 1 1/2" taller, and wider core larger tanked radiator I did some research ahead of time. Most guys seemed to have problems with the mounts, not the metal part but the rubber part as the 2 and 3 row rubbers are to small. So I ordered a set off rubbers for the CU730, so I wouldn't have to modify mine.

My experience. The radiator fits, but it was a much more tricky and required more modification to install than I had expected. First issue I ran into. I was doing the install on the farm, and I'd left my new rubber inserts for the mounts at the shop I manage in town. Driving the 2 hours there and back wasn't practical, so as a stop gap I cut 2 pieces of heater hoses to the length I needed and then cut them in half length wise. That will work for now, but during the work week at the shop I'll pull the top mounts out and slide the proper rubber inserts into place, so that issue is my fault completely and will be remedied shortly. Next issue, the shroud won't fit over the top of the radiator. I know I should have seen that coming, but the most I'd seen was one guy said he "had to trim the shroud a bit, no big deal". Well it's more like you have to cut the entire top of the part of the shroud off that laps over the top of the radiator. I can do that and if done so it's clean and looks good that's fine with me, but I didn't really bring anything from the shop to do that.... So I cut most of the top of the shroud off by scoring it with a razor knife and snapping it, then I took a couple feet of rubber fuel line and slit it length wise and put it along my cut. It looks okish, probably a lot of people would be just fine with it as is. I left a little bit more of the plastic shroud top on purpose so when I'm at work I can cut it and shape it with my angle grinder and / or dremel to look nice and smooth and good. Once the trimming is done the shroud will fully bolt up and sit just like it did before, so this doesn't change the shroud to fan spacing in anyway, so all that should work fine.

Hoses, transmission cooler lines. All that stuff lined up and went together just fine. One more thing then pictures. My old radiator only held about 1 1/4 gallons of coolant, I knew that it had some calcification so I knew it probably wasn't holding as much as it should. The CU730 I just installed took about 3 1/2 gallons of coolant, so it's compacity is definitely much larger.

Pics!

Below: installed and filled!
You must be registered for see images attach


Below picture doesn't really show it, but it does clear the core support without touching, it's a small amount of clearance but should be fine as long as the radiator stays tight, which should not be a problem especially after I get the new rubber mount inserts installed.
You must be registered for see images attach


Below: Top of the shroud. I'm almost a little embarrassed to post this picture, as I thought it looked tacky at the time, but in looking at the picture it's not to bad and will be even better after I trim it properly at work. Will have to be careful not to burn my hands it though! If you look on the right side of the picture see the screw clamp on the A/C line. The truck has had a long standing issue of needed to be recharged each spring. After moving the line around it started hissing there, so I though that clamp on it. Well I guess to good news there is I found that slow leak. So I'll need to replace it this spring.
You must be registered for see images attach


Below, my flavor of choice for Antifreeze, ACDelco classic green. It's available to me though a wholesale supplier (WorldPac) for a really good price $10.50 a gallon. Well that's a very good price around here anyway. plus it's ACDelco! What's better than filling a new radiator in square if ACDelco coolant!
You must be registered for see images attach


I wasn't having any overheating issues, but still I'm looking forward to driving it tomorrow to see if I notice any changes.
Yea that's a good price and I'm in the south east. If we were buddies and closer I'd give you the money for half a dozen jugs of it. Always need it for stuff and putting off coolant changes.
 

80BrownK10

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I actually don't need to fabricate support. My truck has two small separate metal supports on the top it's the plastic shroud wraps around the top of the radiator to the core support. I'm not really sure when they went from the full metal top plate to wrapping the shroud around. It's that part of the shroud that wraps around that is the issue. So really what I'm dealing with is mostly esthetic.

Well drove the truck this morning I want to say that it seemed like the transmission was running 10 - 15F cooler. I've got an external cooler as well, but it goes through the radiator first. I suppose if the coolant in the radiator is cooler, that could translate to cooler trans temps, so that's always a plus!
Do you have a trans temp gauge or were you shooting the pan with an IR gun?
 

SirRobyn0

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@80BrownK10 I'd be happy to hook you up if we were closer, but shipping would kill the deal. However if you have any friends in the area in auto repair the antifreeze came from worldpac and they are a national company, but I have no idea how much price in inventory might vary. I have an auto-meter transmission temp gauge, so I see it all the time and have an idea where it normally runs.
 

SirRobyn0

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Not much of an update. I had hoped to get the mounts and shroud worked out this week at work, but one issue is that the rubber isolator mounts seem to have disappeared completely. Actually I'm starting to think I threw them out at a gas station Thursday night accidentally. I have not re-ordered as I keep hoping they will show up. We've been having some employee issues shop, which looks like we'll have someone starting on Monday, needless to say I just didn't have any free time and the farm is going to keep me busy this weekend, so soon I'll get it all sorted out. It's currently good enough for now, but I do need to finish it up before long.

In the interim I have discovered the larger tanks on the radiator are pushing up against the fan shroud a bit. It's ok right now but I'd be concerned if that could be come a rub point and damage the tank over time. It's actually right where the two halves of the shroud are seemed together halfway down and it pushes right where the tanks meet the core. I think the easy solution is to space the shroud back about a 1/4 - 1/2", of course I know that this will change my fan depth in the shroud but I don't think it'll be enough to cause a great effect. The other thing might be to trim the shroud where it hits the tank and as I write this out maybe that would be the better thing, and that would keep the spacing the same. I could put a little pad of foam on it to just as added precaution. Also would reduce fan suction loss. Yes, I think I'll trim it first, then space if still needed.

For the top I picked up a thin piece of sheet metal. This isn't structural at all. My truck has individual right and left top mounts, this bit of sheet metal will just be to cover the top of the radiator where the shroud once rapped over. This will be the last thing I do after I have all of the mounting and shroud stuff worked out. Now trying to decide if I should buy a inexpensive metal brake, or just do the best I can with whatever I can to bend it. Every time I need to bend metal I want a brake, but never feel like I can justify $100 for something that would be used maybe once a year. Then again I might use it more if I had it....

Well that's my sort of kind of plan at the moment. Hopefully I'll get sometime this weekend, but not counting on it.
 

80BrownK10

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@80BrownK10 I'd be happy to hook you up if we were closer, but shipping would kill the deal. However if you have any friends in the area in auto repair the antifreeze came from worldpac and they are a national company, but I have no idea how much price in inventory might vary. I have an auto-meter transmission temp gauge, so I see it all the time and have an idea where it normally runs.
I got a buddy who works at Ford. More probably if I think about it.

My father in law use to run his own shop, so back in those days I'd just grab what I needed off the shelf.
 

AuroraGirl

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I believe after 80 the core support being different possibly necessitated the new 2 mounts or that GM wanted the isolators to be spaced furthur and done cheaper.. although a stamped thin plate to me seems it would be cheaper but who knows.

this is my dads 75 with 400 and AC

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AuroraGirl

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edit: it looks like your core support has an extra 90 degree bend /step that wouldnt allow this plate i posted to fit on that
 

AuroraGirl

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@AuroraGirl I believe you are right on both accounts. I still have not gotten to making the installation really right. I mean it functions just fine, I just haven't made the top cover yet.
could you take the kind I showed and then just make a bracket or changes to it to attach on your core support? I imagine the spacing for the fan shroud and the built in "hole" that holds the rubber isolators "nipple" would help that pushes through it
 

SirRobyn0

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I've wrapped up the radiator project this morning. I'm going to keep rocking no cover on top of the radiator for now. I might pick up some black aluminum paint so it doesn't stick out so much but it's perfectly functional like that, so I'm kind of feeling like I have more important things to do than bend a piece of metal to go on top. So basically this morning I made the mounts proper for the radiator and got the fan shroud bolted up properly, and I'm calling that done for now.

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Yea, I think if I were to tape off the top of the radiator and hit it with a little black paint it would be just fine. Or at least good enough for me for now lol.
 

Ontheboulder

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Ok so in another thread I made the decision to install a Spectra CU730 in my truck. My truck C20 305 / 700R4, primary uses are DD, hauling and towing 18' open trailer for the farm. Original radiator was copper / brass 3 row 19" tall radiator. I wanted maximum cooling so after deciding the cost of going all aluminum was not going to work out, I went with the Spectra CU730, this radiator is the stock equivalent for 454 W/AC & Max cooling. So it's a very wide 2 core equivalent to at least a 4 core, the 730's core is 2 1/2" wide!!! If you search this site, or the web, you'll find that plenty of guys swap this radiator into their small block trucks as an economical upgrade. I would have actually preferred to keep the cooper / brass but it wasn't practical.

So before deciding to install a 1 1/2" taller, and wider core larger tanked radiator I did some research ahead of time. Most guys seemed to have problems with the mounts, not the metal part but the rubber part as the 2 and 3 row rubbers are to small. So I ordered a set off rubbers for the CU730, so I wouldn't have to modify mine.

My experience. The radiator fits, but it was a much more tricky and required more modification to install than I had expected. First issue I ran into. I was doing the install on the farm, and I'd left my new rubber inserts for the mounts at the shop I manage in town. Driving the 2 hours there and back wasn't practical, so as a stop gap I cut 2 pieces of heater hoses to the length I needed and then cut them in half length wise. That will work for now, but during the work week at the shop I'll pull the top mounts out and slide the proper rubber inserts into place, so that issue is my fault completely and will be remedied shortly. Next issue, the shroud won't fit over the top of the radiator. I know I should have seen that coming, but the most I'd seen was one guy said he "had to trim the shroud a bit, no big deal". Well it's more like you have to cut the entire top of the part of the shroud off that laps over the top of the radiator. I can do that and if done so it's clean and looks good that's fine with me, but I didn't really bring anything from the shop to do that.... So I cut most of the top of the shroud off by scoring it with a razor knife and snapping it, then I took a couple feet of rubber fuel line and slit it length wise and put it along my cut. It looks okish, probably a lot of people would be just fine with it as is. I left a little bit more of the plastic shroud top on purpose so when I'm at work I can cut it and shape it with my angle grinder and / or dremel to look nice and smooth and good. Once the trimming is done the shroud will fully bolt up and sit just like it did before, so this doesn't change the shroud to fan spacing in anyway, so all that should work fine.

Hoses, transmission cooler lines. All that stuff lined up and went together just fine. One more thing then pictures. My old radiator only held about 1 1/4 gallons of coolant, I knew that it had some calcification so I knew it probably wasn't holding as much as it should. The CU730 I just installed took about 3 1/2 gallons of coolant, so it's compacity is definitely much larger.

Pics!

Below: installed and filled!
You must be registered for see images attach


Below picture doesn't really show it, but it does clear the core support without touching, it's a small amount of clearance but should be fine as long as the radiator stays tight, which should not be a problem especially after I get the new rubber mount inserts installed.
You must be registered for see images attach


Below: Top of the shroud. I'm almost a little embarrassed to post this picture, as I thought it looked tacky at the time, but in looking at the picture it's not to bad and will be even better after I trim it properly at work. Will have to be careful not to burn my hands it though! If you look on the right side of the picture see the screw clamp on the A/C line. The truck has had a long standing issue of needed to be recharged each spring. After moving the line around it started hissing there, so I though that clamp on it. Well I guess to good news there is I found that slow leak. So I'll need to replace it this spring.
You must be registered for see images attach


Below, my flavor of choice for Antifreeze, ACDelco classic green. It's available to me though a wholesale supplier (WorldPac) for a really good price $10.50 a gallon. Well that's a very good price around here anyway. plus it's ACDelco! What's better than filling a new radiator in square if ACDelco coolant!
You must be registered for see images attach


I wasn't having any overheating issues, but still I'm looking forward to driving it tomorrow to see if I notice any changes.
I put an aluminum radiator in my 87 gmc, It took a bit of modification to get it to fit, even though they said direct replacement!!
 

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