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MG MGB GT V8 Factory Originals Technical - mustang radiator

For those of you cooling with the 1965-65 mustang radiator could you supply the dimensions? I called "Mustangs Plus" and they couldn't tell me. Also what are the inlet and outlet sizes?? Much appreciated.

Had a curious thing happen. We had some 100 deg heat recently. My engine was running about 195-200 deg on the highway and my fan (puller) was running. So I rigged a switch to disrupt the ground so I could turn off the fan while at highway speeds. The result was the engine temp increased. After the weather cooled of to the 80s tried it again. Engine temp was 185 so again I shut the fan off. The engine temp climbed to 200 before I turned on the fan. The engine cooled down.
I thought that at speeds above ~~30MPH the fan wouldn't add any addtionional cooling. It seems in my car I'm not getting adequat cooling at highway speeds when the ambient temps are above the 80 degree range. Any thoughts?

Here you are Rick
Tony Bates

Hi Rick,
URL doesn't seem to work
Go to
and look for 1965 Ford Musting 289ci
The info is:
Core Size: 16-1/4 X 16-1/2 X 1-1/2
Inlet Header: 3-1/4 X 17-3/8
Outlet Header: 2 X 16-7/8
Inlet Connection: 1-1/2 PASSENGERS SIDE
Outlet Connection: 1-3/4 PASSENGERS SIDE
Transmission Oil Cooler: 6
Engine Oil Cooler: NONE

Tony Bates

I've got a couple of comments and questions about the early Mustang radiator as well. Based on my research on this site, I decided that this was the radiator I was going to use. I purchased a 2 row aluminum model from Northern for the 65 Mustang with the inlet on the lower passenger side. I bought the radiator a year ago and only last week decided to start fitting it up. My car is a 1970. Fist of all, the radiator is a little bit too wide, but not a problem as you can cut down the mounting flanges on the radiator to make it fit. Upon getting it down into the spot I like I found out the the lower outlet pipe runs smack into the passenger side crossmember with maybe an inch and 3/4 to spare. So I sent the radiator over to a radiator shop to have a 90 elbow welded on in place of the straight outlet fitting so I can fit a hose onto this radiator without doing some drastic surgery on the crossmember. BTW, my engine is set WAY back into the firewall and the crank pulley is BEHIND the steering rack, so maybe I'm the only one who will have this problem. Also, I'm using the 289 engine that has the water pump inlet on the PASSENGER side. If you're using a 302, Northern makes a radiator of the same dimensions and cost with the outlet on the DRIVERS side.
I'm wondering how everyone who used this kind of radiator with a small block Ford placed it in the engine bay and was there any issues with plumbing it? A picture would be worth a thousand words....

I'm using a shroud and electric puller fan from the same company and I have to use the "short" water pump and make a custom pulley to make this all fit, despite my radical engine setback. I don't see how it's possible to fit this radiator without doing some kind of mods to the car or radiator, yet I see this radiator is used quite a bit. Maybe the rubber bumper engine bay is WAY different in this respect, I don't know. I would love to see any pictures if they're out there.

Scott Wooley

Hi Guys,
I fitted a 65 mustang/falcon rad. Yes you need to cut the mounting flange to fit it in between the rails and also I cut the panel in front of the rad so that I could move it forwards, all the way to the slam panel. I then fabricated new mounting brackets. This gives plenty of room for a puller electric fan in front of the 4.2L Rover engine.
Tony Bates

Are you using inner guard ventilation holes, as per RV8?. They make a big difference. It's a Low pressure zone in those wheel arches.
Best of all, they are free!

I've seen them on cars without the RV8 exhaust, They often put a bit of mesh there, just for the look of it. Though the mesh is not really necessary; nothings going to come in with all that hot air rushing out.

We regularly get hot days here in northern California, last week was something like 113 and I drove the V8 to work. No cooling problems but I have recently gone through my cooling system thoroughly. I made sure to get all air pockets out of the hoses, made sure the cap worked and sealed well and made sure the overflow held more than the amount of coolant that passes into it at temperature so I don't get any air back into the system. I say at around 195 in traffic, no puller fan but I do have an air dam to duct the air through the bottom of the rad. At stoplights, I get up to 205 and stays there or goes down if I turn on the stock pusher fans. I don't have any holes in the inner fender and no louvres or scoop for the heat to get out. Stock late MGB radiator with larger ports to match the Rover hoses.
Jake Voelckers

Tony-Thanks for the measurements. Did you have better cooling with the mustang radiator than what you replaced?
Jake-What are the diameters of your inlet and outlet ports? Seems like your getting good air flow through the radiator and out of the engine compartment even in slow traffic!

FWIW, I put a low profile hood scoop on my car to clear the plenum when I installed EFI. Since the EFI gave proplems, I removed it & went back to a Holley. The Holley now gets plenty of cool air via the hood scoop & the car runs really well. But, it now runs too COLD ! I know it's still winter here but the day temps. are in the F60s. The temp guage never reaches normal. The car also has a series of 1" holes cut into the rear of the fenders. I think I've got too much airflow through the engine bay. I'll have to wait for summer to really check it out I suppose. Barrie E
Barrie Egerton


Time for a winter thermostat. :)
Carl Floyd

I am still a long way away from firing the engine for the first time :-)
Tony Bates

A bit more money but it is a 2.5" crossflow ally core rad, welded, not clapmed tank construction.
Bill Spohn

Thanks Carl, I'll give it a try. The chances are the current thermostat is a low temp one to help combat the more common over heating problems. Barrie E
Barrie E

Tape over the holes and see if it makes a difference.
Obstruct part of the radiator as well possibly.
Of cause your guage could also be faulty. This you'll certainly find out if you adopt the above action!

Hi gents,

Great page. I have a 77 MGB with an SD1 3.5 and 5speed. just got all the FI working and now I'm fighting overheating problems. I have a 4 core radiator from TSI imports twin electric fans and use the stock MGB expansion tank. The car runs warm most of the time but in traffic (common place in SoCal)it gets hot enough to pop the 18lb cap an spew coolant on the road (embarrasing).
I have RV8 headers so I have the fender well holes but here is the twist, my car is emissions legal (SoCal)so I have a catalyst, O2 sensors, the works. I'm thinking my headers run hotter than non-catalyst cars but my cooling system just can't keep up. One though is to completely remove the thermostat (currently 165 deg) to improve coolant flow. Any help would be great.


Mark Mallaby

Mark, with the mixture of parts that people use to create these monsters, make sure the water pump is turning in the correct direction. This seems to be an easily overlooked item.

Keep the thermostat, but maybe replace it with a known good one.

Obviously, no kinks in any of the hoses is good, but could there be an air lock? Is the expansion tank the high point? Not sure how susceptible these engines are to keeping air.

And, do the fans move air through the radiator with the engine compartment closed up?

Wayne Pearson

I like the way Wayne is thinking. I prefer to start with "the basics".

If you have the thermostat temporarily removed, it's easy enough to observe whether it opens properly by putting it in a sauce pan of water and heating it on your stove. (Incidentally, I've read multiple places that automotive thermostats are designed to be part of a system. When people remove their thermostats there's some associated risk of changing pressure and flow rates in different parts of the engine block and heads... causing "hot spots" or other unexpected consequences.) I had to replace a broken thermostat on my old Plymouth once.

If you haven't already, double check that the electric fans aren't spinning backwards. (Could polarity be reversed?)

Check your ignition timing and the function of your vacuum advance too.

You might find a few more ideas in this article:

Since you indicated that you've recently gotten a new fuel injection system working, my bet is that your fuel mixture is set too lean. Could you have a bad sensor? Does the "map" need tweaking?

This article may interest you too:

(Note: the new issue of the British V8 newsletter won't be officially published for about one more week while I complete ad designs for a couple more sponsors. Consider the Tuning article a "teaser".)

OK latest update,

Water pump is a Buick 63 skylark short nose bolted to SD1 cover. Both units spin the same way, had not checked that before...good call.

thermostat opens at correct temp with good flow.

Unfortunatly smog engines do run lean to meet emissions, in CA that is a given (I'm perfectly OK with that I like clean air).

Last night I bled all air from the system (lots of air) so I need to devise some strategic bleed holes similar to BMW motor. Also weakend the coolant mixture to about 30% coolant 70% water (was the other way around). This helped a bit. Car still got hot but not blow your guts on the street hot.

One thought is my air filter (K&N) is in the engine bay with no cool air to breath. Has anyone found moving the air in front of the radiator panel to help cool the charge entering the engine to make any difference?

Thanks so far... The saga continues.
M Mallaby

Are your headers Jet Hot ceramic coated. Big help with under hood temps. My crossover pipe is coated, as well.
Carl Floyd


One way to deal with air in the coolant system is to use a header tank (overfolw tank) and place it at the highest point in the engine bay. I have used several different types over the years, including the metal tank from a TR7 or TR8. The one on my GT is from a Vovo 240 with a cap from a turbo car- higher relief pressure. As this is the high point in the system, this is where the air accumulates, and as pressure builds, the air is expelled.

My FI roadster uses the stock MGB expansion tank, but I fill the radiator by removing the top hose. This minimizes the amount of air in the system, and I have never had an air block filling in this way. By the way, the FI manifold has a fitting up front on the drivers side tht is "wet". I have no idea what the original purpose was, but I fitted a short length of rubber hose to the fitting with a radiator drain valve on the other end, and I have cracked the valve once or twice to see if any air would come out, and did get just a bit on one occasion.

Ah...the saga continues

Over heated on the way home last night about 85 degree outside temp (i'm getting over the embarrassment phase and moving toward acceptance). Expansion tank filled and over flowed once I stoped it realy got going flushing itself into the street.
So...last night I fabricated a cowl to collect air from the intake ports under the bumper and boxed it all in toward the bottom half of the radiator. I then built another cowl to cover the fans and box in the top area of the radiator. Currently it's roof flashing and duct tape, if it works I'll fabricate something more permenant. I also switched back to a 18lb cap on the radiator and a 20lb on the expansion tank that is located at the high point, It's attached to the heater box at the highest point that will allow the hood to close. I took it for a drive in 72 degree temp nice evening for tool to the coast. let it idle for a while and drove home. On the freeway it was good right in the middle of the guage. At idle it went up to about 3/4 and held there. On the drive home It recovered a little but did not get any hotter so OK for now. Did'nt drive it today will try warm weather on the weekend.

I'm thinking about wrapping the headers, any thoughts?

M Mallaby

Mark, two thoughts... 165 degree thermostat may be too low in higher temps. i've seen where using a higher temp thermostat improves cooling by slowing the flow through the radiator. Might try something like a 185.

Also, you asked about wrapping... if your headers aren't coated, that's probably a big source of the problem. Either wrap them or get them ceramic coated which looks a lot better.

Lastly, i don't recall reading whether you have any sort of holes in the inner fenders to let the hot air out of the engine bay. If not, you may need to put some there (it's a low pressure area so the engine are tends to get sucked out from there). I've even seen one car recently (Leondard Marshall's) that has 5-6" electric fans mounted there to help move the air out at lower speeds. It was a slick idea & he did a very clean job of it. I can send you a pic of that if you'd like.
x Ficalora

ok, that was three thoughts... i guess i can't count! :).
x Ficalora

Good cooling is a combination of several things working together.
1. correct radiator cap 13 to 16 lb cap
2. Rob F. suggested a thermostat 185 Yes. 160 in the desert.
3. Ensure the electric fan is getting 12v big culprid install a relay
4. Engine timing. If retarted, it will create heat
5. Carb, correct jetting and correct mixture.
6. air flow in the engine bay
7. Keep hot air off the radiator, resurculating hot air from the engine bay into the radiator.
8. A big mistake, Do not use water softerner water, it contains salt and the cooling is not effective. use destile water from the store. Good for a 5 to 10 degrees cooler.
9. Trap air in the cooling system. Follow Jim's advice
10. Adequate radiator capacity and fan cfm's
Bill Guzman

Read the articles on cooling in the British V8 newsletter. If your engine is not completely stock it is likely that your distributor needs to be recurved.

Jim Blackwood

This thread was discussed between 09/08/2006 and 01/09/2006

MG MGB GT V8 Factory Originals Technical index

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