Technical Another Ford Guys Question!

Anyone know much about 400 motors?
This is my first one, and it runs hot. I think by reading some threads that it takes a very special THERMOSTAT.
Motor runs wonderful and ton of power but I hate getting stuck over heating on the road.
Thanks,
Greaser Bob

 

The 351C, 351M, & 400 all use a special thermostat that has an extension on the bottom that seals off the bypass when the stat opens. They will over heat with a standard stat.

 

I have a 400 in a jailbar with 4 speed and 2.78 gears....our summers are usually around 45 deg Celsius or 113f
and have no trouble with temp...I use an ordinary t'stat and have an engine fan

 

Do you have the restrictor plate? Lots of guys have removed them not realizing the role they play.

http://www.ebay.com/itm/351C-Bypass...ands-/171476456933?hash=item27eccb15e5trictor plate?

B

 

^^According to the description in the EBay add, it is not for the 400?^^
I wish I had a picture of the exact one I needed so don't get the wrong one.

 

I've ran 400's for years and never heard of this special thermostat.... just make sure your coolin system is adequate...

 

Yes it does use a special restrictor either in block or on stat . You will run super hot with no fix and a busted bank account tiring to fix with out it

 

That's exactly what I'm trying to avoid! Anyone have any photos of said t-stat?

 

All right, this is what I'm finding so far. Because the 400 block has the restrictor already cast in it, it only needs this thermostat.

 

Use search, there's a Thread on the 400 somewhere here for info on your engine. The C & M use the closed type of thermostat pictured above instead of the open bottom type.

 

The 400 does not have the brass restrictor plate. The block has a smaller bypass hole which does not require the separate plate. But they still use the special thermostat. You may get by with a standard stat if you have a good enough cooling system but your engine will run cooler in hot weather with the correct thermostat.

 

Now I just need to find where to get one, as I really don't think they should be an arm and a leg!

 

Should be available @ your local parts house.

 

I've been unsuccessful so far

 

I drove a truck with a 351-M for years and I think I put a regular T stat in it and never had any issues except when I used a gutted T stat in it which ran slightly warmer.

 

I believe that the 351-400 m are reverse flow cooling systems. check it out. later, matt.

 

Honestly my motor is a bit racey(sp) and I'm using a re-cored clean oem radiator. So the t-stat is just something I have to get right.
It never pukes coolant, but I'll be taking it up to Santa Maria next month and I don't want overheating problems.

 

What's your definition of hot.

15lb cap will give you a boiling point of 257 F, if it is not puking water, are you sure it is boiling.

 

Not puking but pegging my oem type temp gage in my '54 Ford truck. Might hook up a gage w/degree marks to see exactly what it's running.

 

You ask for one for a 71-3 Mustang with a 351C?

 

No, I've been asking for the 333-180 and or hoping to cross reference it. Near as I can tell, the bottom copper part is supposed to expand when it opens and drop into a hole cast in the block to promote circulation back to the radiator to help cool it.
I don't know what's in it right now-will be taking it out VERY soon to heat it up in a pot and see if the bottom brass part expands outward.

 

Alright, thermostat is out. This is what I'm seeing just inside the block. Looks to me like the center hole is what needs to be blocked off when thermostat opens. Going to boil my thermostat I have right now and see if it opens. Butt the thermostat I have looks like it will never block off the center hole. So off to the parts stores I go!

 

Yep, t-stat opens. But the part that comes down is smaller than the hole it's supposed to be blocking off.

 

STILL trying to figure this bastard out!

 

The extension does not completely block the hole and it does not need to do so. It only reduces the volume flowing through the bypass when the stat opens.

The 351M/400 is notorious for cracking exhaust seats. Have you had the system checked for exhaust gas in the radiator?

 

What shape is the radiator in.

 

Just finished a Torino for a guy with a 400 m . Used a standard thermostat and it doesn't overheat in the Florida summer so it won't overheat anywhere.

 

Thanks guys. Radiator is in real good shape although original makeup. And now I'm using an electric puller fan behind it to help in idle traffic. Pulled the t-stat out and have been running it that way, but think I'll put it back in to make sure to cool the rear of the heads. I just keep thinking of the head gaskets put on backwards theory. And I don't want to yank the heads.

 

And no I haven't tested for exhaust gases in the coolant. Wonder where I can get a tester kit now.

 

Maybe that original radiator is just too small is my thought..