[Krow]

I have a Q, on the driver side the head does the coolant dead head in back of it? I know the coolant flows up from block then I assume the coolant moves toward the front of the head into the crossover... I'm sure this has been talked about on this forum somewhere. And is it advantageous to run a coolant line from the back freeze plug on the head to the front of the crossover or route it somewhere else I'm sure this has been done before.. Any results you post here would be greatly appreciated either positive or even negative results about this mod... Thanks all

[JLMounce]

There's a few threads around that discuss this. For a street car, it's probably no big deal to leave it dead headed.

If you're going to be racing the car in a manor where you have high sustained rpm and are generating a lot of extra heat, getting the heat out of the back of the head is going to be advantageous.

[steve25]

Its the same for a drag only motor of 600 hp or less, there's no need for the added plumbing!

[Krow]

I'm running a 455 with a 6-71 and I took the motor apart this year and changing a few things it's a street car but with the added heat with the blower I can do the mods since the motor is apart now... Ill look for the threads on the forum but in the mean time where do guys run the coolant line to from back of head to the coolant crossover? Anyway thanks for the replies

[steve25]

They go from the back of the head like where the heater hose. Nipple would be , up to the sender holes on each side of the water outlet on the water crossover, but the lines cross from left side to right side.

[gene simmons]

Back of head to water x-over cooling
http://forums.maxperformanceinc.com/...d.php?t=797808

[Krow]

Thanks for the the post and link that helped

[lust4speed]

My way of looking at it - you have coolant at back of head and two choices. Allow the coolant to flow through the head to the crossover absorbing heat as it travels to the front, or create a shortcut and allow coolant out at the back of the head and shoot it to the crossover without it absorbing heat.

[Blued and Painted]

Originally Posted by lust4speed

Allow the coolant to flow through the head to the crossover absorbing heat as it travels to the front, or create a shortcut.

This flow is said to be improved if two or three of the most forward coolant holes of the blocks deck are plugged. This would reduce dilution and turbulence with the incoming coolant and returning coolant from the back of the head. And create more of a circle track effect.

I would think plugging the block would be preformed before final Plate Honing.

[TedRamAirII]

I agree with Lust4speed. Letting coolant out the back of each head doesnt allow the coolant to pick up and carry the heat away towards the front. Dead heading the rear, I dont believe does anything. The left side is always dead headed, while the right lets a little out so the heater gets warm. So maybe the right head may run a little warmer than the left, not enough to warrant any modifications. I would do the "Barcak Mod" and let her rip. Seems like someone could make a Head Gasket with the holes plugged and then instructions to drill the "421" hole and be done with it. http://forums.maxperformanceinc.com/...ghlight=barcak

[Tom Vaught]

Originally Posted by lust4speed

My way of looking at it - you have coolant at back of head and two choices. Allow the coolant to flow through the head to the crossover absorbing heat as it travels to the front, or create a shortcut and allow coolant out at the back of the head and shoot it to the crossover without it absorbing heat.

By not allowing a proper amount of coolant flow thru the heads, you basically make the engine run hotter because the heads run hotter.

With the proper coolant flow thru the heads the heat is carried away. If you rob water and just sent it to the cross-over you actually are making things worse as far as the engine/ head heating goes not improving things coolant wise.

Tom V.

[BruceWilkie]

Pontiac engine cooling... http://www.pontiacsafari.com/EngineCooling/index.htm
The link describes diferences in cooling from early reverse flow to conventional for 1960 up. The flow drawings arent the best but combined with system descriptions and how they work you'll better understand how each work.

Take note of the block drillings in 1960

Three upper are blocked(prevents water short-cutting to crossover) ALSO the "421 mod" hole was present in the block long before 421. See center of 56 and 60 block decks.

[gene simmons]

Originally Posted by lust4speed

My way of looking at it - you have coolant at back of head and two choices. Allow the coolant to flow through the head to the crossover absorbing heat as it travels to the front, or create a shortcut and allow coolant out at the back of the head and shoot it to the crossover without it absorbing heat.

That's how i was looking at it as well.
I don't see a restriction by running the heater hose to the cross over.
Water is flowing through the hose as well as inside the head.

So after 2 threads and general discussion,is this a worthwhile modification?

If i understand Toms reply correctly,it doesn't seem to be,but then again,i am not restricting flow through the head.

[TedRamAirII]

Originally Posted by gene simmons

That's how i was looking at it as well.
I don't see a restriction by running the heater hose to the cross over.
Water is flowing through the hose as well as inside the head.

So after 2 threads and general discussion,is this a worthwhile modification?

If i understand Toms reply correctly,it doesn't seem to be,but then again,i am not restricting flow through the head.

You are not "restricting" flow, you are "bypassing" flow through the head. I dont think taking coolant from the back of the head and "bypassing" the cylinder head is a good idea, which is what you will be doing. The hose from the back of the head is not involved in helping the cooling system keep cool, its strictly for the heater core. If you dont have/want heat, there is no reason you cant put a freeze plug in the head to cap it off. Then cap off the heater hose nipple at the water pump.

[Bill Eveland]

It sure helps getting air pockets out of the driver side head, especially on initial fill. I can imagine having flow out of both heads is one of the best ways to prevent this. I ending up blowing out head gasket between 5 and 7 because of an air pocket and driver head running hotter .

[Blued and Painted]

I blue a heater hose at Commerce in a late round at 1K feet. Needless to say, i caught allot of flack. I've restricted the head nipple to .250 ever since. Even if the currly-q restrictor exists. A good water pump at hi rpm's is no joke.

The other huge by-pass is the intake to timing cover. I plug then drill the intake to .250.. I know these mods are nothing new but they are effective reducing bi-pass and forcing a larger percentage of coolant thru the radiator.

The next intake i come across, i'll plum a small diameter steel line from the left head to the sealed intake exhaust crossover. Then possibly to the temp switch fitting on the thermostat housing. Reducing heat soak time is my intention. Bleeding air from the left head would be a byproduct.

Cams and head flow get all the headlines but the lowly cooling system needs TLC too.

[BruceWilkie]

Originally Posted by TedRamAirII

You are not "restricting" flow, you are "bypassing" flow through the head. I dont think taking coolant from the back of the head and "bypassing" the cylinder head is a good idea, which is what you will be doing. The hose from the back of the head is not involved in helping the cooling system keep cool, its strictly for the heater core. If you dont have/want heat, there is no reason you cant put a freeze plug in the head to cap it off. Then cap off the heater hose nipple at the water pump.

Well stated!
If you ran lines from rear AND blocked the front crossover holes(at the head) there MIGHT be merit in that, as all coolant would head in one direction.
However, that could also unbalance the temps front to rear. Only way to know is by testing (properly). Wouldnt be that hard to do.