Ford 302 Cooling System

[Richard Knight]

Hi, Does anyone have a diagram showing the flow of coolant around the engine / radiator etc. I have a 302 engine and the two small outlets on the water pump have been bridged - I assume these were for the heater matrix, and at the back of the heads there seems to be coolant ways which have been blocked off, I'm worried that this will over heat the heads if there is no flow! Any help will be greatly appreciated.

Cheers

Richard
[email protected]

 

[Mike Dozier]

Richard

Several builders bypassed the heater ports on the water pump. In fact some just pull the nipples out, plug and tap shut, apparently with no ill affect.

I suspect the plugged holes in the back of the heads
are the smog pump connections...no harm plugging those.

MikeD

 

Richard,
Greatings from Texas, the coolant is drawn from the bottom of the radiator by the water pump which delivers the coolant to the cylinder block.The coolant travel through the cored passages to cool the entire length of each cylinder wall. Upon reaching the rear of the cylinder block, the coolant is directed upward into the cylinder heads, where it cools the combustion chambers, valves and valve seatson its return to the front of the engine.The coolant from each cylinder head flows through the water passages in the intake manifold past the water thermostat, if it is open, into the top of the radiator. If the thermostatis closed, a small portion of coolant is returned to the water pump for recirculation.
As far as the the plugs, make sure that beside your upper radiator hose, you have a small 90 degree hose from the thermostat housing to the top of the water pump. On the passenger side of the pump will be a nipple which connects to one end of the heater core (supply), the return from the heater is located on op of the intake manifold just behind the thermostat housing and beside the water temp. sending unit.
The plugs on the back of the heads are from smog ports of a late model 5.0, unless you plan on using the engine as a late model with computor, don't worry about them.
Good luck,
Bob (SHO40)

 

[Gary Gibbs]

[ QUOTE ]
Richard,
On the passenger side of the pump will be a nipple which connects to one end of the heater core (supply), the return from the heater is located on op of the intake manifold just behind the thermostat housing and beside the water temp. sending unit.


[/ QUOTE ]
Great discussion except you have the heater circuit backwards. Any connections at the intake will be outputs of the engine (thus inputs of the heater and bypass hose), and all nipples connected to the stock style pump are inputs (suction thus would be returns from the heater).

 

[Julian West]

[ QUOTE ]

Several builders bypassed the heater ports on the water pump. In fact some just pull the nipples out, plug and tap shut, apparently with no ill affect.


[/ QUOTE ]

I'm not fitting a heater & was intending to simply run a hose between the heater in/out ports on the engine. Is this not necessary if you simply plug the holes ?

I take it the small 90 deg hose is the bypass when the stat is closed?

Also, my radiator has a 10mm bleed back connection in the top corner. Where does this plumb back into the system?

I've also been studying this thread http://www.gt40s.com/ubbthreads/showflat.php/Cat/0/Number/51855/an/0/page/0#51855

If anyone has diagrams here it would be a great help!

 

[Chris Duncan]

""I'm not fitting a heater & was intending to simply run a hose between the heater in/out ports on the engine. Is this not necessary if you simply plug the holes ?""

I believe so

""I take it the small 90 deg hose is the bypass when the stat is closed?""

Yes, but I have this question also. Do you need a bypass when you're running a racing Tstat that has larger bleed holes than a normal Tstat? Also if you're running an expansion tank then the small line from behind the Tstat to the tank also acts as a bypass. I'm asking because I'm running an electric pump and the 90 deg hose is eliminated.

""Also, my radiator has a 10mm bleed back connection in the top corner. Where does this plumb back into the system?""

You can run it back to your expansion tank or you can just leave it unconnected. All you would then use it for is to bleed the air out when filling the system, then just leave it closed.

""I've also been studying this thread http://www.gt40s.com/ubbthreads/showflat.php/Cat/0/Number/51855/an/0/page/0#51855""

""If anyone has diagrams here it would be a great help!""

The diagrams linked on the thread you mention are the only ones I could find on the net. I think the "stock car, endurance racer" comes closest to the typical GT40, the only difference being the smaller low pressure line from the expansion tank usually Tees into the large low pressure line running back to the pump because the expansion tank is located in the engine compartment. This diagram even has the correct "auxiliary plumbing" lines running from the back of the heads to the Tstat area.

 

[Jim Rosenthal]

Does anyone have an opinion as to what temp thermostat to run in my 302: 3x2 Webers, moderate hydraulic cam, AFR 185 heads? I don't know what the 'normal' Tstat is for these motors.

 

[Mike Dozier]

Suspect there are a lot of opinions....but IMHO a 180 stat
is a good compromise for the street. I'm amazed at how hot
new car stats are these days....200 or higher is common...

MikeD

 

[Howard Jones]

I have a 160 degree in mine but I am going to try a 180 also. I think that the 160 is open all the way all the time and is not keeping the water in the motor long enough to get a good transfer of heat. I will admit I'm guessing but then I seam to do a lot of that with these cars. Its gonna be a trial and error thing I would think. If you are going to buy one I would start with a 180.

 

[Mark Clapp]

Howard, I'm betting that the 160 is open full time as you think and I've heard an engine should not be less that 180. I use a Mr. Gasket high-flow 180 degree unit. It is unshrouded and supposedly very accurate on the opening temp. They are available from Jegs such as on this page I use a stock water pump and figured the extra flow out of the block would be a good idea. My car stays at 180 even on the hottest days.

 

[Richard Knight]

Cheers for the info, though if anyone still has a diagram, it would be most appreciated.

Richard

 

[Chris Duncan]

On this web page (pdf)

http://www.meziere.com/2003_catalog/30.pdf

the "Stock Car, Endurance Racer" diagram comes closest to the typical GT40, the only difference being the smaller low pressure line from the expansion tank usually tees into the large low pressure line running back to the pump because the expansion tank is located in the engine compartment. This diagram even has the correct "auxiliary plumbing" lines running from the back of the heads to the Tstat area so common with custom manifolds.

When you say the passages at the back of the heads are blocked off are you talking on the intake side of the heads or on the bell housing side? Some aftermarket intake manifolds block coolant passages at the back of the heads on the intake side. Typically this is where you install the "auxiliary plumbing" so these passages aren't blocked off. Passages on the bell housing side are EGR ports.

This is the best diagram I've seen, although it's simplistic and doesn't show line sizes, if I get time I'll draw one and post it.

line sizes

Tstat to radiator 1-1/4", 1-1/2", 1-3/4"

Radiator to water pump 1-1/2", 1-3/4"

(flow is better if feed is smaller than return)

original GT40 has 1-3/4" feed and return, many kits have 1-1/2" on both. The new GT has 1-1/4" feed, 2" return.

Auxiliary plumbing from back of manifold (heads) to behind Tstat. AN4 or AN6

Bleed line from behind Tstat to expansion tank AN3

feed from expansion tank to low pressure side before water pump (return) AN8

overflow line from expansion to overflow tank AN3

Optional remote water pump in engine compartment, 2 lines to 2 inlets of engine AN12

Here's a thread that shows "auxiliary plumbing" lines
THREAD