Technical torque converters and overheating

Hi all,
My name is Paul and I am from New Zealand. New to this forum and the H.A.M.B but I have spent hours reading various posts and comments made, always very interesting and enlightening!
I have a 1939 chev coupe, here in NZ, it runs a 454/400 engine is mildish! sorry dont know all the specs but has alloy rect port, 115 cc chamber, cam is mild 515-520 lift 268-280 duration, all new, block was hot dip cleaned, new freeze plus etc, runs Holley TBI setup on a single plane manifold.
Trans is a 400, shift kitted and heavy duty clutch packs etc, converter is std turbo 350.
Diff is 9" 2.7 LSD
My problem is I struggle to keep this thing cool! around town and in slow traffic is not an issue and I can leave it idling for long periods without an issue but as soon as I get out onto the open road or give it a boot full or climb a hill the temp starts to slowly climb, and at times gets up to 220 deg, will come down if I pull over and leave it running! The radiator is a copper 4 core, runs stock pump and due to space confinement I run a good quality 225watt 16" puller fan on the engine side of the radiator, I have extensively shrouded around the grill and engine bay area to force air through the radiator.
I have had it to supposed experts with all kinds of ideas including alloy radiators, electric pumps, fitted the alloy heads, mechanical fans etc etc but the above current set up is as good as I can get it and it worries the bejesus out of me at 220deg!
I have recently been told that the issue could well be the torque converter, its off a 350 trans, this is in there because the cars previous owner was told it would act as a high stall and would suit this application! my trans guy confirmed this!
Any suggestions?

 

Is the transmission ran to the radiator? Or on its own cooler? I don't like running my cooler lines to the transmission, no need in preheating the transmission fluid. Is the radiator new? Flowing good? I'm a fan of aluminum radiators with the double 1" cores.

 

How is the timing set, initial and total?

 

Radiator core is brand new and I run that anti boil cooling fluid, Liquid intelligence I think its called! separate fan cooled trans cooler mounted under the guard! thanks for the reply!

 

The Holley computer runs a trigger mechanism off the cam and it has LS style coil over to each plug, 35deg all in! thanks for the reply

 

220 for an LS isn't over heating....

 

The TBI and ignition set up was installed after I started having the issue, was supposed to be the answer to my worries! yea right! $5k later!

 

its not an LS though!

 

Running a hood? Could it be losing air flow through the radiator at speed?

 

If it's isolated from the rad, then concentrate on the trans and cooler. The LS runs high temp in cooling( forboden here), but for sake of helping- Trans temp at fully normal operation, should be on the "normal side" at 180* give or take...... We're not discussing newer stuff here, as you have an older trans,and a newer engine.......... I'de go with the trans specs,= the way it's been since they went the way of the Do Do bird........
You can match the two, but different outcomes,results........... And YES, they will vary. Good Luck

 

Late to post.........What is it then? Late model engines require XXXXXX, old school th350's require
XXXXXX.............

 

Yes, its the car on my profile pic, have spent a lot of time building shrouds and ducts to force air through the radiator, there is no belly pan fitted and I have opened up some grills on the side of the hood to allow air to exit! this picture shows the grills I fitted to the hood sides!

 

Sorry not sure what you are asking/saying here? engine block is 454, dated to 1973, heads are new alloy, trans is turbo 400, converter is from a turbo 350!

 

Whenever I had a car that would not cool on the hiway but was fine at lower rpm around town, the culprit was the coolant flow through the radiator was insufficient at speed down the hiway. If the coolant flow is restricted, like a radiator that's plugged at the bottom or the core is restricted. They will just keep gaining temp till the rpm comes down to match the flow of the radiator coolant. Just what I have experienced. Lippy

 

I took the thermostat out long ago, pump is new as is radiator (3rd radiator I have had in it) and the block has been hot dip cleaned, I have had an electric pump on it for a period, none of this helped sadly, have checked inlet and outlet temps on the radiator, thinking that if there was a blockage it should show up, top of rad was 210, bottom was 195! that was after a 7 km hard thrash around some country roads here! What else is there that could be causing a restriction?

 

Sucking the bottom hose flat at higher rpm? Spit balling here

 

Have you tried running a thermostat. Say like a 180? Maybe with no thermostat it needs a little restriction to cool. Maybe your coolant flow is TOO fast instead of not enough. When we removed thermostats in a race engine we ran a restrictor washer to limit coolant flow. Just wondering here. If the radiator was of insufficient size I wouldn't think it would run cool around town at low speeds where low air flow would be an issue. So did taking the thermostat out have any effect? Usually not because it will still reach the same temp just take it a little longer without the thermostat.

 

What would you class as higher RPM? cruising at about 60mph, crank RPM is around 2000rpm with this diff setup, crank pulley is just slightly bigger then the pump pully! I do know what you mean though, seen it happen on a race car once!

 

Since the trans fluid isn't being run through a cooler inside a radiator tank, there is no way it can contribute to the increased water temperature...it's nothing to do with the trans or converter. As far as stall speed the TH 350 converter will only add maybe 150-200 rpm more stall than stock 400 converter, so this is also not a contributor to your issue.

This is one of about 3 possible issues:

#1 - enough air is coming through the radiator at highway speeds, but the core isn't big enough to cool the engine when you place a load on it....core isn't big enough.

#2 - air flow through the core isn't enough when at speed or under a load. Core might be big enough, but either air entry, or air exit out of the engine compartment is not sufficient. The narrow nose on these cars from the mid-late 30's is a known problem for just getting enough exposed core area to do the job, or enough air into the nose.
Have you tried an air dam, vertical straight down 2-3" and 3 foot or so width right below the bottom of the radiator?? This creates a low pressure area behind it, helping to draw hot air out into the slipstream instead of the free flow of air under the car trying to stack up into the engine compartment. Nearly all new cars are equipped with an air dam or chin spoiler for this reason.
The Big Block is also so much bigger than the stock engine , physical size, it crowds the engine bay and air can't get around it and out the back side of the engine bay/down the firewall/out the bottom the way it originally could.

#3 - Could also be a case of the 16" fan being shrouded too tight, if all the air coming into the radiator has to exit out through that 16" circle behind the radiator it will become a restriction at road speed. fix here is spring loaded flap openings on the rear shrouding.

Do you have the ability to run it down the road without just the hood, as a check for a lack of air exit volume being the issue?? I see the tilt front, so I'm guessing the hood can't be separated from that?

Alloy radiator may be in your future.
Electric pump will make things worse, they flow less than the stock pump at cruise/open road speed.
A 6 or 7 blade mechanical fan will pull a lot more air than any electric that will fit in the space.

 

You are right, it just took a bit longer to get there! I have not tried a restrictor, any suggestions on size hole to try? Have used 160 and 180 deg thermostats in the past!

 

If it's cooling down at idle then anything above that.

 

What rear end gear? Is converter real loose?
I would think with a “mild”454 that a high stall converter would be unnecessary. IOW if you’re revving the piss out of the engine because of a loose converter behind a high torque engine it’s obviously going to create more heat. If the cooling system is marginal it’s going to run hot when beating on it.
I had a car that never had overheating issues with the stock cooling system. I went from 3.23 to 3.90 gears and it would run about 20 degrees hotter. This was also on a stick car.
Just throwing it out there.

 

You could knock the center out of a thermostat and try that. I think Eric is also on to something about the grille size on your car and maybe it needing some type of air dam under the nose to grab extra air . But I am still (in my feeble little mind, ) wrestling with the notion it's not enough radiator for some reason. Lippy

 

Thanks for that, its a 2.7 diff, converter is a stock turbo 350, another member above has said its only giving it 150-200 rpm! haven't had the engine more then 5500 rpm, that's where I have set the limiter! car is used as a cruiser rather that a racer, that's why I have left the tall gears in! dont have to "beat on it" for it to get hot! highway cruising at 60mph, NZ roads tend to be a bit windier then the states but our temps of late have been up to 95 deg however! not helping the situation!

 

100% believe its airflow, grasping at straws with Torque converter querie! and I have spent hours building ducts etc, even has a scoop! small but as much as I could for the height of the car! as for a bigger radiator?? buggered if I know where I could put the thing!

 

Have you run a thermostat with this radiator? My good friend (deceased) had a radiator shop and NOTHING left his shop without a thermostat, period. I believe the restriction raises pressure in the block and helps quench hot spots, while flowing sufficient volume at sufficient velocity.

Since we're here, a copper/brass radiator will outperform an aluminum radiator of identical size and design... so your 4 row copper should be enough, if not more radiator than you need.
.

 

Oh boy, here's a loaded gun of a topic, so be prepared to read as I try my best to explain what's going on in my head... Take a look at my avatar picture - 39 Chevy, yay, but I'm in your wheel house. From stock, the entire engine bay was designed to be an air box, the straight 6 was shrouded on the bottom, large louvers on the back of the inner fenders and hood sides, and all that air flowed nicely out by the toe boards. Worked like a charm. On your front fenders, do you have the fender grills - and if so, do they have ducts that funnel air to the rad? Those are important. Talked to a guy from Minnesota who filled his in and noted higher engine temps after doing that mod. Second: behind the grill was a piece of sheet metal that was designed to "catch" the air and direct it to the rad, think of the long part of an arrow, the arrow head being the grill. A guy here in Winnipeg had a cooling issue with his 39 Chevy years ago and it was solved by simply putting this part back in it's original place.

Copper is more efficient at transferring heat, but aluminum is preferred for rads, mostly due to cost and weight. Your choice there.

Now with your shroud, this is where things get simple (yeah right): pictures of yours would be helpful, but here's what I"ve learned from people in the race car world, tech article series on cooling hot rods from Street Rodder magazine(RIP) and a few other people's hot rods I've had the "privilege" to fix... work on ... When you compare open rads with an engine driven fan - and feel the air flow - there's a LOT of air flow, (my 64 Chrysler's fan pulled so much air through my new aluminum cross flow rad that I had to make it less efficient because it was cooling too much) but there's a magic number on spacing the fan away from the rad, and having a certain design of shroud that promotes the air flow, they in some way have a funnel shape, with the exit being a bit larger than the diameter of the fan. "Ok, that's nice, but still doesn't help me here, but keep blabbing mr. Smartie pants" is what you're probably thinking,

So now look at the designs of the shrouds in any newish vehicle - the air flow going out must match potential air flow going through, but not create high pressure zones which would trap air in the rad. In a typical hot rod scenario, space is at a premium, so a sacrifice must be made, and it seems it's always in exiting air flow through a rad. You mentioned you extensively shrouded around the rad and have a 16" electric fan pulling air through. Study rad shrouds of newer Corvettes, or even regular cars you'll find in junk yards, they likely have multiple air exit points built into their shrouds, and even then, the shroud box must be a certain distance away from the back surface of the rad to prevent that high pressure zone which eliminates air flow through your rad.

The fan: A puller is always going to be more efficient than a pusher, so good on you there, but look at blade design: the most efficient, according to my research, is a straight blade fan, but this is at the sacrifice of being louder operation, many fans come with a curved blade design for quieter operation at the cost of air flow.

Try this Bill Nye the Science Guy experiment: Works best if you found someone with a wind speed tester, but your hand feeling for air flow should do in a pinch. Got a fan in your house? The good 'ol box fans are easiest to work with, put a piece of cardboard on either side of the fan. Now the fan won't blow (Wow! did not see that coming, said sarcastically). Fan sounds different too, and you likely won't feel any air pull from the back of the fan if the front is covered. Now cut a 16" hole and test again... getting better, and should sound different too. Now build box sides and space the face of the shroud out further from the fan, less pressure build up and more force through that 16" hole should be the result. This should feel like more wind speed. Even try this with your rad fan held in the open hole, because it will create some resistance too.
Now add some "doors" along the sides of your shroud, and even tape some paper to create flap doors (take a look at a C7 Corvette rad shroud for reference). You can replicate these flaps using rubber from junkyard cars rad shrouds (I did that), and punch some holes in other spots to promote air flow, but make sure your fan is not attached directly to the rad core, otherwise you're only using a very small portion of your rad, everything else is blocked off from pressure build up. Play around with designs using cardboard, when you're happy with the results, then go at it with your shroud.

I hope this was as clear as mud, this turned out to be a larger post than I expected. Whew, time for a beer. Take it as advice, try the experiment (I hope I explained it decently enough), talk to some rad shops for their professional advice, and I won't get into an argument with anyone here who wishes to call my 10 cents 'bull funky'. I'm just trying to offer suggestions that have some real world and scientific backing, and not involve huge outlays of cash on your part, unless it proves necessary. Keep 'er between the ditches"

 

I had the EXACT same problem in a 40 Ford Pickup (with 37 passenger front sheet metal) It would idle and cruise around town at 180, take out on the hi-way and it would slowly climb to 235. get off the hi-way and it cool back down to 180...IT JUST DOESN"T MAKE SENSE. It took 2 years to figure it out that it was radiator VOLUME.
With the narrow '37 nose, I had a custom 4 core rad. built and with the mechanical water pump, at higher rpms (hi-way driving) the too little amount of water was pumped through the radiator too fast to be cooled down. I even tried a 3' gate valve on the bottom hose to slow the flow...which helped the Hi-way issue somewhat, but it restricted too much and would overheat around town. Finally, out of desperation, I mounted an additional radiator under the pickup bed (run off the heater hoses) and problem solved...had trouble getting up to 180. The cooling system just needed MORE water volume.

My suggestion is to find out the how many Qts. of coolant are required for a Heavy Duty 454 Chevy truck (block & radiator), then drain down your block and rad. and see if there is a big difference. It's an easy test and won't cost you anything to check It maybe a simple as a bigger Radiator, or an auxiliary water source.

 

Your grille looks to be made out of punched sheetmetal of some kind but the 'slots' appear to represent no more than 50% of the surface area. Besides limiting airflow by virtue of the say 50%, I'd be thinking that the might somehow create turbulence thereby hampering flow further.

Thinking about this further, I can't think or anything vehicle with a grille requiring airflow that's made like yours. There a plenty that you can't actually see through but they're typically made of canted slats which probably don't disrupt the flow much, if at all.

You could test this by removing the grille and going for a run.

Chris