In a few weeks my 455 will be complete and ready for transplant in a '72 cutlass. The new motor has ported C heads, a moderatley aggressive cam and 10:1 actual CR. Should I make cooling system changes now or see how she runs?
The present cooling system appears stock and the car is a 350.

Thanks,

George

 

I would wait and see how it runs.

 

Yes you will need improvements. First start up on a new engine is not the time to find out your 32 year old cooling system that was designed for an engine that's a 100 CI smaller isn't cutting the mustard.

 

When I did my swap to a 455 I left the old cooling system in. It was fine until I got into heavier traffic and longer stops, it never got alarmingly over temp but if you have the resources there is no reason not to make improvements.

 

+1. Unless your 350 came with heavy duty cooling, you will need a larger radiator sooner or later, but you may only notice it on hot days on uphill grades.

The 350 radiator should be fine in traffic if it, as well as your fan, fan clutch, and shroud are all in good condition, but being under load in hot weather will be the thing that makes it hot.

Install a temperature gauge, and check out replacement radiators, and make it a priority when you notice your temperatures climbing when it gets hot out again.

- Eric

 

Sounds like the shortcomings will show up in traffic, on hills, on hot days.
If this is like 5% of the driving, could I solve the problem with an easier(I think) bolt on solution like a supplemental electric fan. In fact, could I get rid of my mechanical fan, for a high flow electric and save some load on the motor?
My fan shroud and radiator are in very good shape. The fan looks to have some sort of centrifical clutch, I think. It has a center hub that has small fins or ribs.
Thanks,

George

 

You can do anything you want, but if your radiator is inadequate, your engine will overheat under load.

We still know next to nothing important about your current cooling system, other than that you have a fan shroud and a clutch fan.
Is you radiator a 2-, 3-, or 4-core unit?
How many blades does your fan have?
What is your fan diameter?
Is your fan clutch working well? Is it actually factory, or has it been replaced?
Does your car have A/C?

We can all BS all day about whether a theoretical 350 car will need theoretical cooling system upgrades under theoretical conditions, but we can't tell you anything without facts.

In the end, the answer to your question, "Should I make cooling system changes now or see how she runs?" is, as I said, see how it runs, but start scoping out radiator options, because come summer, you'll need a larger radiator if you had a non-HD 350 cooling system in there.

- Eric

 

As others have said I would also change it size of the engine plus performance upgrades may be too much for the 350 radiator to handle especially since it is fairly old

 

Here's what I know;
Radiator is 29w x 18" tall. this is the section that air can pass thru.
Overall it's 34 1/2" wide.
I don't know how to tell if it's a 2, 3, or 4 core.
The fan is a 19" dia. 6 blade.
The car has an A.C. unit, but no pump is currently on a belt off the motor.
I do not plan on installing one.
The radiator looks brand new. I've had the car 6 months.

Thanks for the help. I'm all for doing what's needed, but I'm sure most of you know what a motor build does for the checkbook.

George

 

take the cap off and look inside the radiator . You can usually see all the openings which are what the coolant runs through . Count how many you see in a row( 2,3,4 or the new fangled aluminum / plastic tank radiators have much larger tubes so there are only 1 large in them ) Also , you say your new Larger 455 engine is a 10 to 1 engine , so you have more cubic inch and more compression , which the later makes more heat , so you do have something that seriously needs to be addressed . At least take the radiator down to the radiator shop and have it looked at and ASK questions . Stewart , or other manufacturers also offer a higher flowing water pump over standard that may help . Be sure and run a thermostat , check your radiator cap . Always remember that if you spent THAT much money on the engine itself , you at least owe to yourself to protect it (and your checkbook ) from destoying itself by doing the whole job correctly .

 

Like this:



This is a 3-core.

For a 455, a 7-blade fan wouldn't hurt, but the 6-blade should be fine for all but the hottest days in the heaviest traffic, at least if you're not using the A/C.

And speaking of the A/C, if you don't plan on using it, take off the condenser and put it aside in a safe place - your cooling will improve, especially at low speeds.

- Eric

 

Good picture, Eric
I have a 3 core radiator.
The compressor is off.
I will use a higher flow water pump.
I would never run without a temp. gauge.
I will explore a better radiator or some type of supplemental cooling.

Thanks for all the tips.

George

 

IMO, I'd keep it as-is, just make sure the clutch actually engages. It's usually around 200deg or so. The fan will suddenly sound like a jet engine even at idle.
If it never engages then replace the clutch with the nicest "heavy duty" one you can find. The non-HD ones are absolute trash, and the HD ones currently sold aren't great either.
Just run it and see what happens. Also make sure your thermostat is in good shape.

 

You may be able to get away with the three-core, depending on ambient temperatures and usage, if the three-core is in good condition. If I recall, non-A/C, non high performance 455s came with three-cores. That means that the presence of the condenser in front of the radiator may make the difference in whether this radiator does the job or almost does the job.
Of course, a 4-core or a fancy aluminum radiator is probably the overall best choice when push comes to shove, but you've got enough chance of doing okay with the radiator you have that I'd recommend waiting to see how it behaves when it gets warm again.

- Eric

 

After everything you have done and money spent I wouldn't even hesitate to put in the proper radiator.

 

You at least need to take your stock radiator in and have it torn down and see if it's in good shape or not. I just couldn't put a new engine in a car that has that many more cubes and think a 32 year old radiator was going to do the job, at least for long.
If you can afford to rebuild the engine you can afford to rebuild the cooling system so you don't cook a new engine. Ask me how I know about cooked engines.

 

My non stock 455 sits behind a cheap aluminum epay radiator. I run a shroud and 6 blade fan with a clutch. Never goes above 180 even when it's 90 outside. I do also run aluminum heads and intake. 4 years running now. I think the radiator was around $200 when I bought it. Can't remember the brand that was placed on the Chinese part.

 

Why are we creating a solution to a problem that does not even exist yet? The OP lives in CT not Texas or Florida.

 

Exactly. Find out what your options are, then see how it behaves come springtime.

Simple.

- Eric

 

My radiator looks brand new.
It's a 3 core unit.
I have a 6 blade clutched fan.
The shroud is in mint shape.
I'll do the wait and carefully monitor approach.

I thought perhaps some folks could describe the stock setup from the factory for a 455 with Auto trans and no AC.

Just found info on Wild about cars;
AMA spec sheets (2) comparing cutlass L.C & H.C. 350 engine and 442 with 455.
I'll list the specs in order. cutlass 350 L.C. / Cutlass 350 H.C. / 442 455

Cooling capacity 11.5 qt 14.5 qt 15.5 qt
Fan 4 blade 4 blade (6 blade with A/C) 4 blade (6 blade with A/C)

I have a 6 blade fan and I'm not re-installing A.C. and
I can measure the volume of the radiator when I do the engine swap.

Done deal!
Thanks everyone, it was an engaging conversation.

George

 

Someone may correct me, but I believe that a 455 with no A/C and no HD cooling got a 3-core.

Of course we'd all rather have a 4-core, but I believe that that was what GM thought was adequate.

Remember that cooling system volume includes the heater core, which is a different size in A/C and non-A/C cars.

- Eric

 

The capacities I listed were "no heater" included. The spec sheet gave both.

George

 

Ah. Good.

 

But do they include the block in the cooling capacity?

 

It doesn't say on the spec sheet.
15-17 quarts is 4 gallons. That's a fair amount. I'd say it counts what's in the block.

George

 

I would have to agree. If the cooling system is in good condition with all the correct parts (shroud, seals, etc) and the tune is good I bet the engine will be fine. Only after a problem shows up would I suggest replacing parts. If it ain't broke don't fix it! However, if parts do need replaced then it would be smart to upgrade.

 

If that's the case, then one needs to remember that the big block has longer water channels than the small block.

 

While we can speculate all day on yet to be encountered situations, I find it a bit crazy that after building such a nice engine and all that time and money spent you wouldn't just put in the better radiator if there is any doubt.

 

I find it a bit crazy the way that some people replace perfectly good parts without any reason to believe that there's anything wrong with them.

- Eric

 

Amen!!!

 

X3

 

I had a 72 Cutlass with a 350/th350 with A/C and a 3 core radiator. I replaced them with a 455 .040 over with an RV cam and th400. I took off the A/C compressor and evaporator because the compressor was locked up. It would get as hot as 210 on the highway. Most of the time it ran under that. I'd say try it out and see how it works for you in the spring.

 

I'll have a go at it.
Thanks.

 

People replace parts for many reasons and pure need is usually the least of the reasons. They replace them because they need to be, because they feel like it, or because the want a sensible upgrade. Like a heavy duty radiator. After spending time and hard earned money on a vehicle to me the cost of a radiator for insurance, peace of mind and a make sense upgrade is what I would do. If you would rather take your first summer road trip with your fingers crossed, that's you perogative.

 

Ha.

Two years ago I took a summer road trip on a 104° day with an untested engine and a bad feeling about the radiator.
I had no evidence that the radiator was bad, so I didn't change it.
I did put a spare radiator in the trunk, though.
Ended up blowing a leak In the middle of the core and changing it in a 7-Eleven parking lot.
Ran fine the rest of the nearly 1,000 mile trip.

So yes, I would rather not buy parts until I'm absolutely certain I need them.

- Eric

 

To each their own.

 

I recently dropped a 455 in my 69 442 to put the 400 on the sideline. I have the same two core no issues. My specs are similar to your 455 w/o the head work and I have 10.5 pistons. Before you go crazy with changes see how it runs first. Not a must but mechanical gauges are helpful, in other words I would put my money there as opposed to changing something that doesn't need to be yet. Didn't read every thread here but some of this probably was already stated. Hope this helps

 

Thanks.
A real life example is worth 100 opinions.
But I really do appreciate the treasure of knowledge, of all the members, and how they
always offer guidance to us that often need it.
Thanks You all,

George

 

You're welcome.

We don't all always have the same ideas or suggestions, but taken as a whole, we tend to give good and thorough advice.

- Eric

 

couldn't of said it better