Cooling.
 

What about the backwards head gasket issue? I know it's a pain in the butt, but you have to get that right.

Surge can is completely unnecessary unless you have air in the system or don't have a high point for filling.

The rear air bleed is a great idea. I would not install a valve...you want that bleed path present all the time in the event of thermonucleatic boiling in the heads that cause air pockets to form over time. You know those tiny bubbles that seemingly form out of nowhere on the bottom of your sauce pan when making pasta? That happens in your heads too. Those tiny air bubbles will collect back there and before you know it, you have a big air pocket. Look at some factory high performance engine designs and you'll find these bleed paths are either there from the factory, or added afterwards by those that push their engines and have discovered the problem.

Timing is unlikely to do what you're describing. If it was that far off, your exhaust would be glowing red or it would be running so bad you wouldn't have had it running for that long before you shut it off.

A mechanical fan and shroud will provide more flow than your planned pushers. If you want powerful pushers, look at SPALs offerings. Push fans are not nearly as effective as pull fans. You will burn twice the amps making a push fan work. Do this only if you have to; pull fans are much better if you have the room for it. I didn't have room; believe me I tried; and am running a pair of powerful SPAL pusher fans. They draw over 80amps at first power on, and over 40 amps sustained on high. I run a 200A alternator mostly because of the fans.

http://www.racesystems.com/cobra/ima...nSpal1750s.jpg

My radiator is a huge, heavy, ridiculous brass monster made by some supplier for West Coast Cobra in Canada. If the car is moving at all, the fans are off. This includes road race duty in hot weather. They don't come on until I pit. I hate the weight and bulk and over-all appearance of the radiator, but boy does it work. http://www.racesystems.com/cobra/images/radiator2.jpg

If I did it all over again, I'd let Matt design the whole thing...radiator, fan, and Shroud assembly...with my Meziere water pump built into the radiator tank. That would probably take 30lbs off the nose of the car. https://the-fan-man.com He's also a good source for the SPAL fans if you're looking for them.

FWB said - you keep mentioning a flex fan, gives me an image of a cheapo aftermarket mechanical fan"
Actually, What I am using is similar to this: Flex-a-lite 1317: 17" Stainless Blades Blue Center | JEGS

ByronRACE thx... I was only going to do the petcocks because I'm not sure if that is the issue...then I would plumb it in.... but from what you say, maybe I'll plumb it now.

- checking Temp Delta.. but what/ where? Radiator Input vs output? What's a good value ?? 10 ; 15; 20 degrees?
Air delta? I have an infrared Thermo gauge but suggestion for Air medium?

Sooo would any of these following points below hold water(not really a pun).......or can crack/void be so small it only leaks under running high cyl pressure?
- Wouldn't the compression test indicate bad head/block/gasket?
- Wouldn't the radiator test (26/28 hrs) indicate bad head/block/gasket?
- I've run it for about an hour several times...if bad head etc, wouldn't it burst the hoses? Max was 20 PSI..

I'm pulling the intake today to drill/tap for petcocks (maybe bleed lines)....but i'll wait until I get my "Cooling System Vacuum Purge And Refill Kit" from ebay($35 investment) to add coolant.....
Have any of you used the vacuum purge system? YouTube videos look logical...

thx again all!
PJ

Head Orientation
I'm sure someone would have mentioned this by now.....but are the heads interchangeable....
i.e. Right head and left head...as I bought it in a basket in '71 so I never knew which head was which.....

The heads are '68 ..... C8VE-E (said to come out of a '69 T-Bird).
Interesting..the cast # C8VE-E are right above the second exhaust port from the right (as you look from the headers)....One is inverted...the number is upside down....Why????

If I had to change them out...now would be a good time:-)

Thx.
PJ

With all your telling us about your engine and cooling system, it should be running much cooler than it is.

Are you sure you didn't install the thermostat backwards? It happened to me and my temps mirrored yours until I found the problem.

Good thought...but when I'd try one it was right side down...
!
I got the intake off and drilled/tapped..need to pick up parts and reassemble w/bleed hoses...
Thx
PJ

that is exactly what i envisioned, you simply are not moving enough air through your rad. get rid of that fan. its for teenagers from the 80's to put on their camaro for bling.

buy one of these used and install it, you will thank me later.
93-96 lincoln mark VIII fan and shroud assembly make sure you get about 8 inches of harness with the plug.

https://www.thirdgen.org/forums/atta..._fan_front.jpg

you are comparing your close to stock motor to Byrons, which had twin turbo's and was a beast, i do love it. but you are doing modifications that will not fix the fact you have no
air going through your radiator to cool it

Thanks....If I go to a used electrical fan that mark VIII fan is tops from everything that I have read. As far as a new fan, it seems like a SPAL would be a good choice.

you will still be needing a shroud with the purchase of the spal.
the lincoln or the tarus assembly will be a complete assembly just requiring mounting and wiring. blocking any gaps for air to go around the radiator is key. air will take the path of least resistance.

I agree 100%with FWB. You need a system geared to a "street" car which means you need to move more air. I use dual Derale 12" fans, shrouded tight, each pull 2000 CFM, with both running at idle I estimate it is equal to about 35mph. MORE AIR, MORE WATER, BURP. It is essential. Make sure you have a high spot for the air to migrate and purge out automatically.

Derale Part no. 16825 but I had to modify the shroud to fit my rad and layout.

That lincoln puller fan recommended above moves a TON of air. You can buy them new, as well...try rockauto. If you have room for it, that would be a great option. I used one on my truck; it's amazing.

460's should not run hot. A friend runs an oil cooler; and we had to add a thermostat (which never opens) to the oil path because he couldn't get it up to temperature. This was in a Superformance.

Today's radiator back flush did nothing to improve system performance. I was hoping to see a large camel-sized turd blow out of that pipe upon initial pressurization, but just a few chunks and a lot of gray water were present. The mechanic went through three cycles of 20 flushes/cycle. Nada. The result? No performance improvement. His initial checks (system pressure drop test, and exhaust gas contamination test) were negative. So, for my $243, I gained nothing...well, sort of. At least I know for sure that my primary (Griffin) radiator is not the problem.

Source
 

https://www.amazon.com/gp/product/B0...=ATVPDKIKX0DER

Ran across this today in my amazon saved items list...thought it might be helpful.

Update
 

Update:
- I R&R intake gasket with Fel-Pro which block the exhaust cross-over.
- I used the "Cooling System Vacuum Purge And Refill Kit" to try to eliminate any air pockets.....it actually worked pretty well.
- I did add the bleed lines to the intake. I drilled a hole in each intake side matching the (blocked) head water ports. Tapped (1/8 NPT) for small hose fittings and connected them with a "T" and then ran it to the gooseneck.
As I mentioned previously the radiator is new; but I have taken it off again and back flushed.....seems to flow fine.

- Results. ( 80+F) ...not much difference.....(I have an in-line radiator cap - no surge tank yet - on order)....I used a "Spill-free-funnel" to be able to monitor it.
- It pushed out about a pint+ or so....it started from about 5 minutes on.
- Also notices very tiny bubbles occasionally....from 15 minutes and even some at 45 minutes.
- I also ran a Strong garage fan on the radiator the whole time....at 40 minutes it was at 195,....when I turned the Fan off for 3 minutes, it went to 210; turned fan back on and it went down to 205.
- When I revved the engine for a minute it would drop a few degrees.

My goal is to keep the mechanical fan, build a better shroud and add two front fans (ERA type). (yes I'm sure the Mark VIII fans would work best).

Next - integrate the expansion/surge tank (and overflow tank);
- Maybe get an undersize water pump pulley.

Again, thanks all!
PJ

Fan Relay
 

By the way, a typical 40/50A automotive relay will *not* power that fan reliably. I tried. I even tried two in parallel. Nope. They both failed and had me cutting and twisting wires together on the road...

This relay, however, has lasted over 60K miles in my truck switching on and off the high circuit on the fan only.

https://www.amazon.com/TE-BOSCH-Curr...osch+75A+relay

Additionally, you want to run at least 12ga wire to the fan. I originally ran 14ga wire and found that there was a 2volt drop at the fan when the fan was running, and the wires would get warm. I ran 10ga and the fan ran noticeably faster with much less drop.

Fan idea
 

The lincoln fan idea was one, behind the radiator, as a puller. No pushers, no mechanical.

I like mechanical fans actually. Reliable and simple. It's just not as easy to work on up there with all that fan and shroud and stuff in the way. When I changed to electric on my truck, I was amazed how convenient it suddenly became to work on. Since then, I've roadside repaired a water pump, tensioner, belt, alternator...all made much easier with all that room up there from the factory fan and shroud delete.

In a Cobra, the heating problems are typically when parked. Electrics really shine in that situation; you still get full cooling power at idle. If the mechanical works well enough at idle, I think that's a win. Simple is better.

Summit: https://www.summitracing.com/int/parts/rnb-620-118/

Rock Auto: https://www.rockauto.com/en/parts/do...+assembly,2181

Just an honest question... Not trying to pick a fight.

You need better airflow to cool your radiator. But you refuse to replace the mechanical fan that is the root of the problem. Why keep complaining about too much heat if you won't fix the main problem?

It's cool if you want the look and are willing to trade the "look" vs "running too hot" but you can't have both. Your call.

"Since a belt-driven fan increases speed (and airflow) with engine speed, it can move more air at higher engine rpm - usually above 2,400 rpm - than an electric fan. Conversely, electric fans move more air than belt-driven fans at engine speeds below 2,400 rpm in typical applications."
Source: https://www.flex-a-lite.com/blog/whi...lt-driven-fan/

In what RPM range are you experiencing cooling issues? Lower RPM, as you indicated "When I revved the engine for a minute it would drop a few degrees."

Electric fans run the same speed regardless of engine speed. A typical electric fan is going to be turning 2,000 - 3,000 RPM - even when your engine is idling. Your flex fan, OTOH, is directly linked to engine speed. Even if you're running a 20% overdrive, at an 800 RPM idle speed it's turning 960 RPM - less than half of what an electric fan will be turning on LOW.

In addition, most higher CFM electric fans like the one for the Lincoln Mk VIII, are using curved scimitar blades which are more efficient both for power and for air flow. Your straight-bladed flex fan - uh, not so much.

Finally, the shroud on an electric fan almost certainly has much smaller clearances to the fan than does your shroud. Mechanical fans are attached to the engine and the engine moves, so clearances can't be as tight. Tighter clearances mean more airflow.

In no characteristic is a mechanical fan superior to a modern electric fan. If you believe the nostalgic look is more important then go with it - but be prepared to accept its many limitations.

Garage cooling fans are great, but you're not getting 2,500 - 3,000 CFM ducted through your radiator. Get your hands on a good electric puller and try it out - even if just to satisfy curiosity. I believe that will solve your problem.