thoughts on cooling


solid fixture here in the forum
The Moroso Stand Alone Twin Tube Heatsink style Transmission Cooler has been Great on the 1963 Gp Grumpy.
I have never seen over 120F trans temps.
Checked with my Inferred Laser Temp gun. And touching by hand. Even after 120-130 mph joyrides !
No fan needed on it.
I don't have a 4000-5550 rpm stall race converter in the TH400 trans in that car.
So results may different for others.
The Teflon Lined Areoquip Stainless lines AN#6 And matching Areoquip fittings with the Moroso cooler was a $600 purchase. Well worth it.

Big fan of taking heat out the radiator and engine.

Standalone cooler on the 1999 Tahoe working great also.
Hayden #679 made for huge motorhomes.
Great deal at $55 bucks only.
30,000 miles 1 year later that time bomb 4L60E I built still holding up.
Fluid bright cherry red.
140F typical.
Highest measure was 170F last summer and it was 93F out.
Checked at cooler in the front grille and trans pan with my IR Laser Temp gun.
No issues last winter standalone. Got down to -23F. Driving 25 miles to work that day checked. 140 F.


solid fixture here in the forum
You can install #8 AN Lines in the Moroso trans cooler if you want to.
Just buy new fittings and install.
N.P.T. threads. Easily found by Earls , Areoquip & others.


The Grumpy Grease Monkey mechanical engineer.
Staff member
Cooling a Mighty Big-Block Chevy is Easier Than You Think
Our big-block–powered 1967 Camaro gets a new cooling system
Tommy Lee Byrd Jul 31, 2019
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Dealing with an old Chevy that got the majority of its modifications in the 1980s is like stepping back in time—and not in a good way. Our 1967 Camaro was originally a six-cylinder car, and like most early Camaros with a base-model engine, the wimpy inline-six was traded for something a little more muscular. In our case, it was swapped for a 396ci big-block with a small cam and some 1980's appearance modifications. While the car will crank and run, our intent with it is to bring it up to modern standards, starting with the cooling system.

The car didn't appear to have any coolant leaks or actual problems in the cooling system, but anything that has been sitting for a long time is susceptible to corrosion and potential problems down the road. At the very least, new hoses would've eased our mind, but we wanted to upgrade the cooling system and ensure that the big-block would run cool, whether it's on the highway or sitting in traffic. For this, we reached out to the folks at Holley. Once known only for its carburetors, Holley now offers a wide range of brands and products, including a new line of radiators and cooling system accessories under the Frostbite brand.

Along with a new direct-fit Frostbite three-row aluminum radiator, we opted for a matching electric fan and shroud assembly to eliminate the old mechanical fan setup on our car. The dual SPAL electric fans are wired in using a Frostbite relay kit, which allow the fans to be controlled by the temperature of the engine. While we had the cooling system disassembled, we replaced the old water pump with a new high-performance aluminum unit from Weiand, and replaced all of the fittings, hoses, and even the hard transmission lines. We finished it off with a Mr. Gasket universal overflow tank.

We spent a weekend in the shop assembling and installing the cooling system upgrades, and the results are impressive in both performance and appearance. The new radiator and water pump are lighter than the originals and we should be freeing up a couple of horsepower by removing the mechanical fan. And let's not forget the fact that the big-block now runs cool consistently, no matter the conditions. With a collection of new products from Frostbite, Weiand, and Mr. Gasket, we brought this big-block out of the 1980s and into the modern era with a high-performance cooling system. CHP

Welcome to the 1980s. Our 1967 Camaro's six-cylinder engine has been swapped for a big-block and the only modification to the cooling system is a flex fan. We're going to bring this cooling system into the modern era with a new radiator, fan, and more.

Looking a little deeper into the cooling system we see a crusty, cast-iron water pump. We'll also replace the radiator hoses, heater hoses, and remove the mechanical fan altogether.

While we allow the coolant to drain from the radiator, we loosen the transmission cooler lines. After further inspection, the transmission lines are kinked in several areas, so we'll install new hard lines as part of our cooling system upgrade.

We removed the four bolts holding the radiator and lifted it out of the engine bay. This radiator was not leaking, so it will go to the swap meet pile and we should be able to get a few bucks to offset the cost of our upgrades.

The flex fan will also go into the swap meet pile. Yes, people still use them, and yes, they are still effective. However, a mechanical fan is only effective if there is a shroud to help direct the airflow. In this case, the fan had no positive influence on the cooling system.

After removing the alternator and associated brackets, we can loosen the four water pump bolts and remove the crusty water pump.

We're replacing the original water pump with a Weiand Action Plus aluminum water pump. Despite the lightweight design, the pump features a heavy-duty shaft, pulley hub, and impellers.

Using a Summit Racing engine bolt kit, we attach the new Weiand water pump to the block. We did have to run to the local hardware store to get a 3/8-inch bolt that measures 3 1/2 inches in length for one of the four water pump bosses.

The heart of the new cooling system is a Frostbite aluminum radiator. It's an FB148 model, which is a three-row unit that can handle 450-750 horsepower, so it should be perfect for our big-block. The Frostbite radiator bolts directly into place on our 1967 Camaro.

The new Frostbite high-performance fan shroud assembly (PN FB513H) is a perfect fit for the 23-inch core in our FB148 radiator. We start by mocking up the SPAL electric fans in the pre-cut holes using a pen to mark the holes that need to be drilled.

We drilled four holes per fan, being sure to keep the protective film on the shroud during this process. We used a 1/4-inch drill bit.

The kit did not come with mounting hardware so we grabbed a handful of 1/4-20 bolts, making sure they were 1 inch in length.

Once the fans are mounted to the shroud, we can then attach the shroud assembly to the radiator using self-tapping sheetmetal screws in the pre-drilled holes.

We took the opportunity to clean and paint the radiator support before sliding the new Frostbite radiator and shroud assembly into place. It is designed to use the original bolt holes in the radiator support.

Installing the radiator is as simple as tightening four bolts. The position of the new Frostbite radiator is the same as original so all of our original-style lines and hoses can be installed easily.

Any time you service a cooling system, it makes sense to replace the thermostat and thermostat housing. The previous housing was chrome, and those are known to leak, so we replaced it with this stock-style one. We got the thermostat, housing, and gasket from

To connect the dual SPAL electric fans, we used a Frostbite relay wiring kit (PN FB403). The kit includes this temperature sending unit, and we threaded it into the port closest to the thermostat. This will ultimately control when the fans turn on and off.

We picked up four new heater hose fittings from Summit Racing and applied thread sealer to prevent leaks. We also used a formed hose to make the 90-degree bend from the intake manifold to the water pump. If you ask nice enough, the local parts store may let you search through their formed heater hoses to find something that you can trim to fit.

The original transmission cooler lines were toast, so we bought new ones from Summit Racing. Although they were pre-bent, they required some tweaking to fish between the engine and crossmember. Once they lined up with no binding, we tightened them with a line wrench.

New Gates radiator hoses came from The upper radiator hose was a perfect fit, but we had to trim the lower hose to fit. We also noticed that the new lower hose wouldn't fit over the water pump outlet. Our fix involved dipping the end of the hose in hot water, which allowed the rubber to stretch just enough to fit the outlet.

The Frostbite FB403 relay kit had plenty of wire, giving us lots of options for mounting the relay. We chose to mount it near the radiator, where the original voltage regulator was located. The light orange wire connects to a 12-volt source, while the gray wire goes to the sending unit, and the red wire connects to the fan harnesses.

Finally, we attach the large yellow wire to the provided fused power wire seen here. Using terminals from the kit, we piece together the wiring and attach it to the positive battery cable. The only thing left is to connect the ground wires from the fan harness to the chassis.

Once all of our hoses are secured and the connections are crimped, we can pour a mixture of coolant into the new radiator. We ran a short piece of 5/16-inch rubber hose to a Mr. Gasket overflow tank, but a stock tank will also work with the new radiator.


Active Member
Grumpy et al,

There's obviously some good coolant content here, but I'm really interesting in some coverage of common SBC cooling modifications.

I've seen some circle track engines and nitrous SBCs that have hoses running from the back of the intake to either a sandwich plate either below the thermostat, or sometimes added above the thermostat to the gooseneck itself. -> Does this actually help to even out temps cylinder-to-cylinder or better cool the supposedly hot rear cylinders? (If so, how?)

I've also seem modifications made that route cool coolant from the legs of the water pump and then pumps it right in between the center paired exhaust ports.

Going further, some Felpro head gaskets recommend drilling a new 7/16" hole on the deck of an SBC right between those pesky center exhaust ports; they also seem to recommend increasing the existing center hole on the intake side of the deck to 7/16" as well. It looks like GM added these holes to the deck surfaces in the 1989/1990 and later GM SBC blocks as revisions...

Then beyond this, I'm curious how the early stock water pump bypass works and where the tiny inlet hole in the one leg of a stock early water pump goes. (The Vortec pumps and blocks don't seem to have this passage.)

If I have a heater core, isn't that effectively yet another internal "bypass", just like the early stock bypass?

Last one: Those finned heat sinks that you keep recommending that go over SBC oil filters; I'm not sure that they're actually made or available any more. I've made two attempts to purchase something similar and I can't find ANY that fit SBC sized oil filters. I think they may have gone extinct...


  • felpro deck modifiction.jpg
    felpro deck modifiction.jpg
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Active Member
they still sell these and you could modify them or use as designed

this lower designs what Ive used for decades:like:

Thanks. The Amazon one is the one that I bought. It was definitely way to small to fit an SBC oil filter, but I guess if you cut the thing open and pried it open and forced it over an oil filter, it might work.

The one from Mesa Performance lists the 3 5/8" diameter one as "not available at this time"; not clear if this is a COVID supply chain issue, or they've just discontinued the SBC sized ones. I'll reach out to them and inquire.

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Active Member
Last thing on the cooling subject: I live in the very temperate climate of Seattle and wanted to be able to run a greater than 50% coolant mixture to increase my cooling systems' efficiency. I've found a useful online Calculator tool for calculating the "freeze protection" (point at which slush starts to form) vs. "burst protection" rating for a mix of both Propylene Glycol and water and Ethylene Glycol here:

It estimates that a 25% mix of propylene glycol provides "Freeze protection" (slush) to 18F and "burst protection" (actual hard freezing, potentially popping out freeze plugs and causing damage) down to 10F.

There's lots of charts showing the boiling point of different propylene glycol / water blends out there that indicate that a 25% blend provides a boiling point at sea level of 218F.

When I then adjust the boiling point upwards for a cooling system / radiator cap pressure of 16 PSI using your rule-of-thumb, I end up with an estimated boiling point of 266F.

-I store my C3 Vette in my attached garage that won't see below 50F and our summers generally reach a peak outside air temp of 90F. I feel like I can safely run a 25%/75% coolant-to-water ratio, assuming that I add more anti-corrosive / water wetter to make up for the >50% water blend and might even get a small efficiency boost in my cooling system doing so. Does this make sense and seem like I'm likely to stay out of trouble both on the freezing end and boiling end of the problem?

I could've saved money going with concentrated anti-corrosive+water wetter product and mixing my own, but I've gone with a mix of 50% VP Stay Frosty Racing (DI water pre-mixed with anti corrosive and water wetter) and VP Stay Frosty Performance (DI / propylene glycol + anti-corrosive and water wetter 50/50 pre-mix) to achieve a 75% / 25% mix.



The Grumpy Grease Monkey mechanical engineer.
Staff member

adding a remote located fan cooled oil cooler is an option you might consider

if the vettes unlikely to see temps below 40F in winter and you want to insure better cooling under higher heat in summer, the added fluid cooler is not a bad option, but remember you want oil to go above 215F occasionally to remove trapped moisture
if theres room the longer two quart oil filters with the finned collar do a decent job of reducing oil temps


when clearances allow longer length, quality oil filters provide significantly larger surface area, this tends to both reduce pressure drop,
and increase the useful filtration time before the filter tends to partially clog due to trapped debris,
yes they still require frequent replacement but they tend to do a better job, over the same time frame
and of course you can remotely mount oil filters
keep in mind that you have the option to change the oil filter type and length, remote mount single and dual mounted oil filters are an option for most cars



if you have the required ground clearance a deep finned oil pan or transmission pan is an option, this is rarely a good idea on a corvette

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Active Member
I've got a buncha pictures that I've collected that go with my cooling mod questions above, that I could share, but I'm getting errors uploading the images and they're only 640k jpegs, so I'm not sure what kind of special voodoo magic I need to do to get them uploaded here.


Staff member
I've got a buncha pictures that I've collected that go with my cooling mod questions above, that I could share, but I'm getting errors uploading the images and they're only 640k jpegs, so I'm not sure what kind of special voodoo magic I need to do to get them uploaded here.
Images have to be less than 512 KB. Do you have software to reduce the file size? It should be easy to get them below the 512 threshold with some compression.
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Active Member
Thanks @Indycars!

Here's the first picture showing an early gen1 SBC's water pump bypass hole on the passenger side and where it enters the head. My best guess is that the coolant introduced here would just mostly flow through the front part of the head and to the intake and then to the bypass hose between the front of the intake and back into the water pump. -I don't see how this could be very good at actually keeping temps even in the center or rear cylinders. Seems pretty silly, IMO. -Based upon my current understanding of the flow, I think I like the idea of the small holes in the thermostat just allowing bypass flow through the whole engine in the normal way and on to the radiator way better.

Early SBC GEN1 water pump bypass in block.jpg

Here's a later vortec block showing that there is neither a bypass hole in the front of the block, no the "receiving" bypass hole on the deck side.
Vortec block no coolant bypass.jpg

For completeness, here's a pretty high end after market SBC water pump picture showing the crossover port on the pump side:
sbc gen1 early water pump with crossover.jpg

Circle track cooling setup that I really like:
circle track sbc cooling mods (Copy).png
I like this one because it's taking the coolest coolant and moving to to the hottest place, but also because it's helping flow from the warmer rear cylinders and putting it UNDER the thermostat so it will only flow to the radiator until the engine warms up if you add the small thermostat holes. -I WOULD add the thermostat holes and just deal with the slightly longer warmup time. (I know some of the circle track guys run no thermostat or run a restrictor; I'd never do that on a street car, personally.)

I don't have a picture of the "Sandwich plate" solution that goes where the thermostat normally goes and move the thermostat up; with that setup the return lines go into sandwich plate so you don't have to drill the front of the intake. You MIGHT be able to run the thermostat under the plate in the stock location so coolant is constantly recirculating to the radiator from the rear cylinders OR run the thermostat in between the sandwich plate and the goosneck. Not sure; I didn't bother looking into it because with my FIRST TPI intake I just don't have the room to run a sandwich plate.

Another picture showing the rear to front crossover directly into the thermostat gooseneck AFTER the thermostat: (Not a fan for a street car as I actually want the block to get up to temp.):

rear to front cross-over continual bypass.jpg

From what I can tell the SB2 Nascar cooling designs are just TOTALLY different than what we have and they send chilled coolant to the sides of the block between cylinders 4 & 6 and 3 and 5 and then remove the coolant from top 4 corners of the intake; supposedly have completely different head gasket holes to send the flow from the center of the block to the corners of the intakes. That actually makes sense to me as the way to get the most even temps; the SB2.2 heads don't have the siamesed center exhaust ports either, AFAIK, so it seems like the design just exists to keep temps even...

Fun to dive into coolant flow, finally.