Inliners International Forums General Discussion Engines Cooling system mods for high performance engine

I have a '64 Nova station wagon that's been a long term project that's finally getting a lot closer to completion. It has a 250 in it now in place of the original 194. The motor has a Comp Cams 268H cam, Crower steel roller rockers, screw in rocker studs, head work, high compression pistons, Clifford aluminum intake, Holley 390 cfm 4 barrel carb, headers, HEI ignition, and aluminum water pump.

The first thing I noticed is that the motor runs really hot, as in aroun 220 degrees when it's at operating temp. So last week I pulled the thermostat and found that it had a 180 degree thermostat in it. I bought a 160 degree thermostat and drained the cooling system to replace the t'stat and discovered that the radiator was probably the original, and had a 2-row core in it. So I pulled the radiator and took it to a local radiator shop that does high performance applications and talked about options with them.

I wanted to have a 3-row core put in the radiator, but apparently that's old-school enough that no one does that these days. So the shop is going to look into a couple of options, such as a high efficiency 2-row core or an aluminum radiator. They haven't called me back yet, but I should hear from them in the next couple of days.

Anyone have any ideas or suggestions about what would make the cooling system work better other than what I've already listed?

Plenty of 3 core radiator options out there. I have one in my 68 Camaro that keeps up fine with my 250 modified similarly to yours. I also put on a large electric pusher fan. It'll idle in 90 degree heat at 200 degrees tops.

Aluminum radiators have been the norm for hot rods for about 20 years now, and the prices on them have dropped significantly since they first appeared on the market. Larger factory style copper 3 cores can also be used. Aluminum dissipates heat much more efficiently than a copper radiator that it doesn't take nearly as large of an aluminum one to equal what a copper one will do.

I put in a BeCool aluminum radiator plus electric fan. Puller fan, pusher would be better. Complete overkill, I love it! FAN turns on and off at idle, mostly off, I think 195F on, 175F off.

If I could cut and paste from the phone, I'd show you the parts list. You can find it on MyMy 230/250 build thread.

I had to call Be Cool to get the right size radiator.

I got a 3 row radiator. Ran hot, 230 at red lights. I got a new water pump (two) and adjusted the impeller closer to the pump body to close the gap, improves flow they say. Ran hot at red lights. I installed a pusher electric fan in front of the radiator. It still ran hot at idle. As soon as you give it 1200 rpms, temps drop down to normal. Never a problem while cruising at any speed. I did this, i did that, tried timing, mixture, all kinds of things... nothing made a difference. Not severely hot, but just too warm for my liking. Many people said the temp sensor just gets heat soaked near the exhaust port and not to worry about it.

I worried about it. Nothing made a damn bit of difference, it seemed like it was just not flowing enough water at idle, to cool it.

Then I got an aftermarket high-flow thermostat, 180 degree, and it shaved a good 20-30 F from my idle temperature, and even cruising temperatures dropped a little. VERY happy, for me the thermostat was the key. Next step was going to be a high flow pump, but I think I'm done now.

My t-stat is a mrgasket brand but there are others. The body is clearly different looking.

Here's one:

http://www.summitracing.com/parts/mil-16401?seid=srese1&gclid=COvgxMOoq8wCFYwfhgodjAMM1A

not sure its the right part for yours but you get the idea.

I think I have the same cam as yours, 9.5:1 CR and for now, a stock single barrel. Will soon adapt a 2bbl to see if it makes a big difference, then headers.

70Nova,
Thanks for the info. My actual first step was to get a 160 degree thermostat at O'Reilly's. I've talked to more than one radiator shop in Boise and all of them say that 3-row cores are pretty much extinct nowdays. However, there is a high efficiency 2-row core that is also wider than my current rediator core, which will increase the radiator capacity. Between that and the 160 degree thermostat, I'm hoping it will get temps into the engine friendly range. I'm also running Vintage Air A/C, which would make mounting a pusher fan difficult. I already have an aluminum high flow water pump, and that didn't seem to make much difference.

I wasn't running hot at stoplights, I was running hot ALL the time as soon as the engine warmed up. It would just peg the gauge at 220 and stay there. Didn't make any difference whether I was idling or running at highway speed. If the new radiator core doesn't fix it, I'll try one of the Milodon or Mr. Gasket thermostats. It should be the right part. In the description at Summit Racing, it says that it fits just about anyting.

My compression ratio is higher than yours, and I'm running a Holley 390 cfm 4-barrel for a carb. I'm not sure the carb would make a lot of difference, but I have a feeling that the C.R. might. I'll update this when I get the radiator back from the shop and get it in the Nova.

I always drill a 1/16" bleed hole in my thermostats to ensure to air gets trapped.

Do you have enough fan? If you can't transfer the heat out of the rad it'll run hot.

I think you need to look outside of Boise...

http://www.ebay.com/itm/1962-1965-Chevrolet-Nova-All-Aluminum-3-Row-Core-Champion-Radiator-/161968901216?fits=Year%3A1964%7CSubmodel%3ANova&hash=item25b6194c60:g:ppgAAOSw0vBUfqkh&vxp=mtr

http://www.ebay.com/itm/TRI-CORE-FULL-ALUMINUM-3-ROW-RACING-RADIATOR-62-67-CHEVROLET-CHEVY-II-NOVA-I6-V8-/151290777497?fits=Year%3A1964%7CSubmodel%3ANova&hash=item2339a20f99:g:dPEAAOSwoBtW42Ym&vxp=mtr

http://www.ebay.com/sch/i.html?_from=R40...or&_sacat=0

Just about a 3 second search...

Get a modern aluminum 3 core and you won't overheat assuming everything else is OK.

One thing you might consider before buying is pulling out your water pump and inspecting it. Might be a bad pump. Look at the impeller.

Thanks for the link. I just looked at all of those aluminum radiators on eBay, and none....not ONE....had the water inlets and outlets in the right place for a Chevy six cylinder. They're all built for V8 conversions, so that doesn't help much. Trust me, I've spent WAY more than 3 seconds looking for radiator options.

efi-diy, I have an aluminum fan now, but if I need a larger or a bit more exotic fan, they're inexpensive and plentiful. Ditto for high-flow thermostats. There are about 8 or 9 different brands and types available. The two that got the most positive and consistent reviews were the Milodon and FlowKooler thermostats, and they were also pretty inexpensive, so I may order a couple just to have on hand

Run the water pump faster perhaps? Make sure your system and cap hold pressure.

The only time I have had overheating issues was with a 4 inch bore stroked 250 with block fill about halfway up. Not sure if the block fill or thin cylinder walls were to blame. This was in a '72 Nova. I tried various thermostats, drilled or not, various fans and shrouds, under chin spoiler, nothing seemed to matter. Running a big 3 row brass factory radiator from a later model Nova that is about 4 inches wider than original for my car. Never boiled over but ran hotter than I liked.

Overheating went away when I went back to 3.935 (0.060) bore and open water jackets.

Would a radiator and hoses from a 68 Canaro work?

Like this? http://m.ebay.com/itm/New-3-Row-4-Pass-R...1130?nav=SEARCH

If you have enough alternator - consider putting an electric fan on it. They are easy to come by in the wreckers Ford Taurus or Crown Vic...

The Be-Cool guys sent me CAD drawings of a few candidates. I found one that matched with the correct inlet and exhaust and mounting holes.

Aluminum radiator and electric fan = Must. A 2 core aluminum would be real nice for that 250.

I got my 3 row radiator by accident, did not order one. I just wanted a generic replacement and that's what I got out of the box. I think it came from Pep Boys.

Going to a 160F thermostat won't help you if you are overheating with a 180. You will be overheating just the same with a 160. Besides if it did work, you would not want to run the engine too cool anyway. It NEEDS to run at a very narrow temperature window.

I too wanted to run the pump faster, but for the life of me I could not find a smaller pulley anywhere.

I too had an overheating issue - the rad was big enough - not enough fan. You got to be able to get the heat out of the rad.

SBC pulleys are smaller. Have a double groove on mine and the diameter is smaller than stock.

got a part number? This is what I heard too but can't find one smaller than mine, it was a V8 pulley I used to replace the old stock pulley with, and they are the same diameter. I can find BIGGER all day long.

I got it from Orange County Truck and Car shop in CA. SO their part number may be different from other places. This is a double groove chrome pulley that cost me $20. Here's their part number: 60-14210
Link to catalog: https://issuu.com/truckandcarshop/docs/ts_60-72_web
Page 96 on the catalog.

Another thing that is good is a good water pump. those cheap crap ones with stamped steel impellers are not very good and allow a lot of bleed by. I used a water pump made for marine purposes and has a brass impeller with a back plate on it. it provide more water volume and last a lot longer with stainless steel shaft and better sealed bearing made for harsh marine environments. I bought mine here on Amazon
http://www.amazon.com/MERCRUISER-WATER-CIRCULATING-GLM-Number/dp/B004AQUABY

Nice! Does anyone make a water pump with a good impeller but has an aluminum housing?

MBHD

No specs, don't know what kind of impeller or what makes it high flow:


http://www.ebay.com/itm/194-230-250-Chevy-six-High-Flow-aluminum-water-pump-/191809542176?hash=item2ca8bd5820%3Ag%3ABX0AAOSweW5VE2iL&vxp=mtr


I'm thinking of getting this later:

http://www.flowkoolerwaterpumps.com/store/Water-Pumps-Chevy-CID:-153/2.5L/c21_27_93/p188/Pump:-1777%3Cbr%3EChevy,-GM,-Buick,-Olds,-Pontiac%3Cbr%3E%281968-1974%29/product_info.html

Update:

I got a call from Mac's Radiator a few days ago. The high capacity 3-row core radiator came in last Thursday. My original plan was to put it in over the weekend, but it rained Friday, Saturday, and Sunday, so I wound up putting the new radiator in the Nova yesterday. I had to do a little modificatin on one mounting hole, but other than that, everything lined up, even though the new radiator is considerably wider and the old one. I put a FlowCooler high flow 160 degree thermostat in it, and got everything installed yesterday.

I fired up the engine and let it idle for about fifteen minutes. No leaks anywhere. After the engine warmed up, the temp got up to a little over 160, then dropped back when the thermostat opened. I watched it cycle a few times, and after about fifteen minutes, the engine temp went up to about 180 and stayed there. This morning I took the Nova out for a test drive, and the engine temp stayed right at 160, rock solid. So the overheating problem is fixed. Thanks to everybody for all the suggestions.

The next project is to get the exhaust system modified. When Kenny's Rod Shop had the exhaust system built, they had the pipes exit just in front of the rear wheel, which makes the exhaust noise way too loud inside the car, so I need to get the pipes lengthened so that the exhaust exits behind the rear wheel, not in front of it.

Interesting reading about cooling problems on engine making minimal power when idling or cruising..

I want to add to this...
Putting a 160 thermostat in will usually make it run hotter (if the rad and fans are inadequate)... This is because the hot engine will keep the thermostat open all the time, circulating the coolant constantly and not allowing it to spend any time in the radiator... Therefore it will not have time to cool down.
This is a very common mistake I've seen made dozens of times.
Make sure the rad is CLEAN inside and of adequate size.
Make sure the fan is pulling enough cfm at idle. If not, change the fan or install a shroud.
Make sure the thermostat is not stuck open. You will see coolant constantly flowing if you look in the rad cap opening if it is.
It is ok to speed the water pump up, but not by much... It doesn't take much to cause cavitation! This puts air bubbles into the system which is no good. It also greatly reduces flow through the system.

Just some things I've come across.

I stumbled onto something a little while back. My 153 setup has no heater system at this time, (I'm working on a neat little Allstate heater box) and I had looped a hose from the water pump to the return on the thermostat housing. I wasn't running a thermostat, just the ring from an old one. If you loop the heater circuit you recirculate un-processed HOT coolant right back into the engine. The volume is roughly 1/4 to 1/3 of the hot liquid right back into the engine!! Not the best thing you can do when your cooling system is marginal. If you're not running a heater, plug the circuit. If you ARE running a heater, I'd suggest using a positive shutoff heater control valve.

I also found that on these engines, you just about HAVE to run a thermostat. I've got a Cadillac CTS-V radiator and two electric fans as well as a big free standing transmission cooler, but it ran hot with just the restriction ring in the T-stat housing. I installed a 185 degree unit and the problem went away. It went from running up to 260 degrees to running just 190 on the average. The thermostat keeps the coolant in the radiator long enough for it to cool down. I'd never encountered that before, even though I once ran a radiator shop for several years.

It is definitely a good idea to drill a small air bleed hole in the stat body, but never remove the core!
Like you say, Blackwater, the coolant doesn't stay in the rad long enough to be cooled.

I've tried MANY different things to correct a cooling issue on my old 69 Charger.

Water wetter additive had the most significant benefit over all I tried! (I was 19 at the time and could not afford an aluminum rad).

I'm thinking about this one for my 250. Looks like a stock swap.

Does the lower exit straight on yours?
I know it is angled in my Nova.

That should work, once you figure out how to attach it. The way that is set up, it looks like a crossflow rather than a standard top/bottom tank radiator. That means that you're going to have to fabricate some way to mount the radiator to the radiator support, because that one doesn't look like there are any brackets that would bolt to the support. Unless there are some kind of optional brackets or a frame of some kind with bolt holes in the right locations, you're going to have a lot of fun figuring out how to get that to stay in place.

One other thing to consider is whether it's the same width as your old radiator. When I put the new one in my Nova, I had to get a radiator top hose that was 2" longer on one side than the old hose. It was kind of fun seeing the look on the the guy's face at O'Reilly's when I told him that I needed a radiator hose that had a 90 degree bend in it and was 2 inches longer on this end and the same length on the other end. It did take us a while, be we eventually found one that would work if I fiddled with it a bit. It's also likely that the hose connections on the engine and the radiator may be different diameters. Mine were, but then, they were different diameters on the stock radiator too. Some plumber's silicone grease and a flat blade screwdriver came in real handy for attaching the top hose to the thermostat housing.

I don't want to discourage you from getting an aluminum radiator. Just be aware that when you modify something, it's never just one thing that has to be modified for the modification to work. There are just about always unseen or unanticipated things that pop up to bite you in the rear end when you begin to change the way the factory did things.

'Course, that's part of the fun in being a hot rodder. Figuring out how to make parts work that were never designed to be there is very satisfying when you solve the puzzle.