429/460 Overheating Issue

[FWB]

you keep mentioning a flex fan, gives me an image of a cheapo aftermarket mechanical fan to replace a factory steel fan. if i'm correct in my assumption get rid of that damn thing, find yourself a taurus or lincoln mark VIII fan and shroud assembly.

those two pusher fans you posted a link to, may block more air than provide cooling

[cycleguy55]

That's the key question, right? Here's our advice: If you are looking for a performance upgrade then the electric fan is for you. Make sure the electric fan covers 70 percent of the radiator core and moves enough airflow for the engine size (a rule of thumb is at least 2,800 cfm for a 5.0L engine). The electric fan would be a cooling solution for vehicles that typically drive at low vehicle speeds with low engine rpm, such as cruising. If you have a 4-core radiator or towing heavy loads then we recommend you stick with a belt driven fan.
https://www.flex-a-lite.com/blog/whi...lt-driven-fan/

Electric fans now outperform mechanical fans in nearly every application, except towing and dirt oval track racing.

Flex fans are a poor design for performance applications. They move less air at higher RPM, and only consume a fraction less power than standard fixed pitch fans.

Clutch-style fans are inconsistent and we do not recommend their use for any application, if possible.
Stewart Components

[Speedwaypj]

August 9th update -
overheating...... I have tried several things....no real difference ....Motor runs great!
So I’ve tried several combinations and the engine seems to want to run hot....actually ..

Overview; ‘69 429 stroked to 460, 9k on block – bought in ‘71 – now sitting in Cobra rpl frame.
Fresh build – everything changed out (crank/rods/pistons/cam/springs/all bearings/rockers/Hi flow oil pump/ hi flow water pump – (with new backing plate)/Dissy/Holley 750/intake/starter – all except heads n valves.
I’ve run this motor for about 15 hrs over several months;
I’ve replaced the left bank head gasket because it was incorrect. Gasket and block and head looked great.
Running 6-blade Flex-Fan with shroud.
Radiator – New Hi per aluminum ($500) – took off and flushed – its clear
Initial timing @ 16 (tried 6, 8, 12, 18)

Issue – pushes qt of antifreeze out before it even gets hot – tends to run Hot.
Put 21# radiator cap on and it didn’t push any water out, but wanted to get up in temp (220 – 235)
It acts as though there is an air pocket. I bought a non-spill funnel to get air bubbles out....ran it for about 45 minutes on a steep incline, a few bubbles, but then it just overheated and blasted antifreeze all over...(235 F).
Tried funnel a second time...same – pushed out 1 – 1/2 qt antifreeze.
Ran compression test – 175; 170; 165; 170; 165; 170; 174; 175 – with closed throttle (couldn’t do WOT and crank).
(9K miles on cylinders; New pistons; honed cyl only)

I need to turn on aux garage fan to keep it down to 210 after 1/2 hr.
====================================
Seems like large air pocket......I can’t get air out.....
1. so I ordered a -
Automotive Radiator Cooling System Vacuum Purge and Refill Radiator Kit CarTruck
Automotive Radiator Cooling System Vacuum Purge and Refill Radiator Kit CarTruck | eBay

2. Someone mentioned running bleed lines from the back of the engine to the water outlet. So I plan to drill/tap the back end of the Edelbrock manifold where the rear head water ports hit the manifold. (The stock manifold has a water passage across the back). Then tie the hoses together and run it to the top of the goose neck...and maybe put a bleeder valve on top of that.
If anyone has done this please chime in as I’ll take any information available.

There’s a zillion BBFs out there, Help......

[BOBOCobra]

I fought this for an entire summer. Similar issues. Here is how I fixed it.
Overdrive WP pulley. I had to make one as you cannot get an aftermarket pulley smaller than the crank. I did a 20% overdrive. 180 high flow t-stat. Brought idle temp down 10-15 degrees just by moving more water. Next, mounted 2 deraile high flow puller fans (need relays as amp draw is high), one comes on at 190, other at 205. Fully shrouded and covers 80% of core. shrouded fish mouth so ALL air goes through the rad. dropped temp another 10 degrees. I run 100 degrees over ambient on highway and max 210 in traffic on 105 degree days. Once second fan kicks on in traffic it cools down to 200. So, at WOT the pulley is spinning at 6500 rpm, tends to cavitate just a bit but air burps. I run WOT now and then, I run traffic every day, pick your poison. Move more air and more water and make sure rad is clean

[BOBOCobra]

Ran out of space but do the simple things before you start running lines from the back of the heads, etc... Again, you need air and water flow, and the reason you are getting hot is you are lacking on both. Key point you made is that it cools at 2500 rpm idle, you are simply moving more water so you need to do that at idle by spinning the pump faster and having a high flow pump without idle speed of 2500. I idle at 950, pump is almost 1200. The only way to dissipate the heat is move air through the rad fins. There is no such thing as too much. Pull through more air with shrouds and high CFM fans. My fans are as close to the rad as I can get and tilt slightly down to push the hot air down the tunnel. I use a 12# cap and spit about a pint into the overflow on a hot day. 521CID, 580 HP....I generate a LOT of heat

[cycleguy55]

Originally Posted by BOBOCobra

I fought this for an entire summer. Similar issues. Here is how I fixed it.
Overdrive WP pulley. I had to make one as you cannot get an aftermarket pulley smaller than the crank. I did a 20% overdrive. 180 high flow t-stat. Brought idle temp down 10-15 degrees just by moving more water. Next, mounted 2 deraile high flow puller fans (need relays as amp draw is high), one comes on at 190, other at 205. Fully shrouded and covers 80% of core. shrouded fish mouth so ALL air goes through the rad. dropped temp another 10 degrees. I run 100 degrees over ambient on highway and max 210 in traffic on 105 degree days. Once second fan kicks on in traffic it cools down to 200. So, at WOT the pulley is spinning at 6500 rpm, tends to cavitate just a bit but air burps. I run WOT now and then, I run traffic every day, pick your poison. Move more air and more water and make sure rad is clean

CVF Racing makes pulleys as follows:

• Crank Pulleys (1V, 2V, or 3V): 5.7" diameter
• WP High Flow pulley (1V): 5.4" diameter (5.5% overdrive)
• WP High Flow pulley (2V): 5.2" diameter (10% overdrive)

10% overdrive is what I have on mine - works like a charm.

Ford BBF V-Belt Pulleys: Ford 429 & 460 Big Block Engines

Custom may be the only way to go if you want more than 10% overdrive.

[BOBOCobra]

I went back and looked and I was actually wrong as I tried it a couple times, I ended up at 25% overdrive. 10% was minimal waste of time, 20% was close, 25% was right on. Crank pulley is stock 5.25" and WP is 4". I had to machine a small relief on the back side of pulley to clear the pump drive neck. Not a big deal. 2V drive. At idle I'm spinning pump at 1266 rpm but I run a C6, if manual you can idle at 1100 and spin the pump 1450 and it will move enough water to keep it cool unless there is a restriction or a huge air pocket. I do have a catch can and and overflow from the catch can an a 12# cap. I have a small 6AN air bleed line from high pressure side to catch can so any air comes out on hot side. Bottom of catch can drains to low pressure side rad outlet with 10AN. That allows some hot water to suction hose but it is small volume. It insures I never suck air at high flow condition as it pulls slightly from catch can, vacuum pulls air from hot tank and/or from overflow and keeps everything in a nice closed loop and bleeds the air out of the rad before it is pushed to low pressure side or creates a pocket in the high pressure tank. It may sound complicated but it is really very simple. A lot easier than drilling intakes and cross-overs.

[520SC]

Been following this thread for a while now. I'm working on a cooling problem as well. With just the original 4-row Griffin radiator and a 16" high wattage fan, the car can peak out between 235F and 240F when stuck in rush hour traffic (air temperature 87F). I added an HVAC aux heat exchanger and a 265 watt fan in front of the Griffin, tapping off the thermostat bypass line and returning to the inlet of the water pump. Hose diameter in this section of the system is 5/8" ID. Peak temperature in traffic is now 225F. An improvement, but I'm looking for 210F max. I'm soon to install a fan cooled oil to air heat exchanger. If I get a 5F drop, I'll be happy.

Now, to my "educated guess" with regard to big block engine cooling. You cannot follow the same rules you'd follow for a small block or a standard sized FE engine. 460 cid or larger engines will always require much more BTU removal capacity.

That being said, if I am unable to reach my goal of 210F (max), my plan will then shift to installing another "regular" sized radiator, to replace the HVAC aux radiator. I"m thinking it'll be a 3-row. It will tee off my main radiator hoses using a 2" tee and a 2 1/2" tee. I'll install a 16" high wattage pusher fan at the front of the car. So, the car will end up with two "full" radiators, one 4-row, and one 3-row.

No more messing around.

[jhv48]

Replace the thermostat.

[BOBOCobra]

520SC-Here is the question What does it do with Ram Air? If you run at the correct temp while cruising then your radiator is sufficient. At Ram Air you are moving large SFM of air and pushing more water, If you are at say 190 at ram air then you should be 10-15 degrees higher in traffic if you have the right plumbing and fans. Puller fans are WAY more efficient than pushers and dual 12" are way better than a single 16". You can offset them and cover a high percentage of the core and pull large amounts of air at idle and low speeds.
Good Shrouds
Efficient air flow
Good Water flow
Proper Plumbing to allow for proper expansion and return and to release trapped air.
Those are the keys,
My bet is your Griffin is way more efficient than my crappy rad and I drive in 105 ambient and heavy traffic and 212 is the highest I have seen and that was lugging up a steep grade behind an idiot on a 100 degree day.

[520SC]

There are actually two completely different situations in which the car will run at a steady 225F: 1) Idling in rush hour traffic, and 2) On the highway traveling at 60 mph. My C6 transmission coupled with 3.73 rear end gears causes the engine to run at pretty high rpm, so it generates a lot of heat.

The "sweet spot" for my car (where it locks in at 210F) is 25 mph to 40 mph.

I agree that a puller fan is more efficient than a pusher fan, however, if I'm going to "stack" radiators (one in front of the other), I won't be able to fit a puller fan between them. So, I'll be running one puller fan and one pusher fan.

[BOBOCobra]

215 is kinda high for the "sweet spot", you have no cushion. Mine ran at 215 or so at ram on 80 degree days so I drove in traffic and shot the rad with a gun and there was a 30+ degree difference from inlet to outlet. That was way to much difference. I pulled the rad and it was full of gunk, either a bars leak or alumaseal type crap. I had to heat soak it and flush it 15 times and got half a small coffee can of crap out of it. that at least got my ram temp down to 190 and then I could do the rest. difference was then only about 10-15 degrees. inlet was 190, outlet was 175, ran about 195. It just seems odd you would need to stack rads on a street driven car, the back rad will be pulling hot air from the front rad... Have you made certain your rad is clean and you have no air pockets in the high pressure tank side? Water jackets are clean? Have you shot with a thermal for cylinder hot spots?

[520SC]

210F, not 215F.

What water source did you use to backflush the radiator. Seems like the water pressure and volume available in my garden hose wouldn't move much out of there.

[520SC]

"the back rad will be pulling hot air from the front rad."

A similar situation exists when someone swaps out a 2-row radiator for 4-row radiator. The front two rows deliver hot air to the back two rows, yet most will agree that the 4-row radiator will provide more cooling.

[BOBOCobra]

Sweet spot should be no more than 195.
Take it to a rad shop and have them boil it. The heat will loosen up any gunk in there and they can flush it out with pressure washer with hot water. Backflush the block to get the jackets as clean as possible in case there is crap in there and all your doing is pushing crap around.
If you want to try at home disconnect the upper and lower hoses. Take your hose and a 100 psi air hose with a long nozzle and trigger and stuff into the lower outlet and wrap with a rag to get it as water tight as possible, let the water fill up the rad so it is coming out the top inlet and then hold the rag, hose and air nozzle tight and blast with air. it will force a lot of water back through the core and out the top inlet. you then need to let it fill up again with water and repeat. Do it 4 or 5 times. If the water is dirty do it till its clean. It will make a mess but it gets a lot of volume through the core quickly until the air takes over and you have to refill. You can leave the upper hose on the rad and try to direct the flow away from the block. 2 person job, The problem is the water is cold and it wont loosen any hard gunky crap stuck in the tubes but it will flush the tanks and any loose stuff. Or, you can buy a new rad and do your best to backflush the block before you put it in. Ron Davis in Arizona will make one based on your CID and space. He is a good source to talk to.

[FWB]

get rid of the flex fan, they move less air than a factory fan

[BOBOCobra]

Ron Davis will make one WITH the fans and shrouds properly done if you don't want to fab it up yourself. He might have a 3 month backlog this time of year (racing season)

[520SC]

Originally Posted by BOBOCobra

Sweet spot should be no more than 195.
Take it to a rad shop and have them boil it. The heat will loosen up any gunk in there and they can flush it out with pressure washer with hot water. Backflush the block to get the jackets as clean as possible in case there is crap in there and all your doing is pushing crap around.
If you want to try at home disconnect the upper and lower hoses. Take your hose and a 100 psi air hose with a long nozzle and trigger and stuff into the lower outlet and wrap with a rag to get it as water tight as possible, let the water fill up the rad so it is coming out the top inlet and then hold the rag, hose and air nozzle tight and blast with air. it will force a lot of water back through the core and out the top inlet. you then need to let it fill up again with water and repeat. Do it 4 or 5 times. If the water is dirty do it till its clean. It will make a mess but it gets a lot of volume through the core quickly until the air takes over and you have to refill. You can leave the upper hose on the rad and try to direct the flow away from the block. 2 person job, The problem is the water is cold and it wont loosen any hard gunky crap stuck in the tubes but it will flush the tanks and any loose stuff. Or, you can buy a new rad and do your best to backflush the block before you put it in. Ron Davis in Arizona will make one based on your CID and space. He is a good source to talk to.

I'm scheduled for an appointment at a radiator shop for Tuesday morning. There's nothing currently adding to radiator inlet can clogging (if, indeed, that is the problem). The engine is brand new. The Griffin radiator was the only major component I reused. The engine that came out of the car had a rotten water pump and backing plate, and I could see evidence of rust at every water hole in both head gaskets.

[ByronRACE]

Backwards head gaskets directs all the water flow into the front 1/4 of the block; the rear overheats. Water has to flow across the bottom, then up, and back across the top. I've seen it done wrong a number of times. Under heavy load, it'll boil the water in the rear and overheat everything badly if it's under load. One of the instances was in a jet boat. Because of the plentiful cold water and using the lake for the cooling system, it didn't show the problem except the gauge...and that went from normal to "pegged hot" faster than the owner noticed. Total loss. It was at WOT for a good 10 minutes like that before it melted stuff and started banging.

Additionally, if you want the 460 to burp well in a Cobra, make a hole in your intake manifold on both sides in the rear, drill and tap for small pipe to hose fittings, and run hose forward to your filler neck, which should be higher than your heads. You want the fittings to flow a tiny amount of water; make the flow path no bigger than 1/8" per side. It's just for air bypass. Do that and you'll never have trapped air in the rear even if the nose is pointed downhill when you fill the system. Without it...you may. It's hard to find a filler neck that works well in a Cobra. I forgot where I got the basis of mine; I modified it quite a bit. I don't like the big burp tank in the front; with a neck like this...there's no need for it.

http://www.racesystems.com/cobra/images/Running1.jpg

[Speedwaypj]

Lots of good info all - thx for the response....

The radiator is new; and I have taken it off and back flushed.....seems to flow fine. I keeps acting like it has air....

- I believe I need to get a surge can on it to give the water someplace to go.
- I ordered a "Cooling System Vacuum Purge And Refill Kit" to try to eliminate any air pockets...
- I plan to drill/tap rear of Edelbrock Intake where the rear water passage hit the intake and install petcock to relieve any air that may be trapped there.
- Sounds like an undersize water pump pulley might help.
- need to check total timing.
- I plan to add two front fans (ERA type); currently have flex-fan with shroud.

There is a lot of knowledge on this forum...thank you all.
PJ