Water through Intake Manifolds

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Richard Sweet

Richard Sweet

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I'd like to start this thread discussing water flow through intake manifolds. For various reasons, we might alter our I.M.'s and those gaskets.
For example, on my 4 barrel, 273, I used a gasket without a passage for the exhaust heat riser into the stock, cast iron, single plane I.M. because I was getting carb boil, even with a 1/4" insulator gasket under the carb. (Now the center passages are very cold while the end passages still get warmed by the water flowing through the I.M. This is not true. I was mistaken. See my post #23).
I think I've heard of I.M.s with water flow through the heat riser passage, which sounds like a good idea. Not too hot and not too cold. So how could I modify my cast iron I.M. to accommodate this better idea?
Related discussion welcomed.
Thanks, Richard
 
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I have never seen a reason for either a heat crossover or water heating an intake manifold, other than emissions or maybe, and it's a big maybe, fuel economy.

Your distribution issues are an intake manifold design issue. I block the heat off on everything I can. Or, better yet, I use an intake manifold that doesn't have a heat cross over to begin with.

And I drive my junk year round, always have and never have I had a carb icing issue. Ever.

Also note you WILL need to change the tune up when you block off the heat. To the point most likely you will need to have staggered jetting.
 
YR,
If there is a way to get even heating across the I.M., I'd like to do that. I don't want to block off the existing water passages into the I.M..

I'm not sure what you mean by staggered jetting; I have a 1403 Edelbrock, 500 cfm, 4 barrel carb. Since the I.M. inner passages (3,4,5,& 6) are colder, I can understand that those cylinders will need a different fuel mixture than the outer (1,2,7 & 8) ones, heated by water passages, but I don't see how to do that with my carb..

Should hotter plugs be used in 3,4,5 & 6?
Should I go by plug readings?
 
Block all passages and run lines and fittings from head to head... now its even'ish IM temp.

You don't want heat in the fuel.
 
Richard Sweet said:
YR,
If there is a way to get even heating across the I.M., I'd like to do that. I don't want to block off the existing water passages into the I.M..

I'm not sure what you mean by staggered jetting; I have a 1403 Edelbrock, 500 cfm, 4 barrel carb. Since the I.M. inner passages (3,4,5,& 6) are colder, I can understand that those cylinders will need a different fuel mixture than the outer (1,2,7 & 8) ones, heated by water passages, but I don't see how to do that with my carb..

Should hotter plugs be used in 3,4,5 & 6?
Should I go by plug readings?
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Yes, go by plug reading.

You may need a different main jet on the right front than you do on the left front. Or a slightly different metering Rod to either lean out or richen up some cylinders.

It's not as uncommon as you may think.
 
Have you checked the heat riser valve for being stuck closed. This can lead to overheating the intake area.
 
Not for racing, just to improve even temperature in the I.M.. Dual exhaust, no heat riser baffle valve, exhaust heat riser passage blocked on both sides.
 
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In the '60s Ford used this "heat exchanger" on some big blocks. Hot water runs through the casting. You can still get them (reproduction).
03-14.jpg
 
The water gets sucked in the bottom hose and is pushed through the block from the bottom up. Through the heads and out the upper hose in the middle of the intake.
Where the hell do you think the water is going to exit the block if you close the intake off?

You'll have to put outlets in the head and run a Y-pipe for the upper hose unless you put two hoses in the radiator. The cross over you want to eliminate is the return for the water to the radiator. The only way to do what you want is to get an Air Gap intake. The outlet passage is not connected directly to the intake runners

This attached ad this intake has 4 outlets threaded in the water outlets at the 4 corners at the head. Small block chevy . You can do this. And you can use them for what ever your heart desires . But in reality you are wasting your time if you think that is going to increase any power on a cast iron intake. Your intake is going to be the engine block water temperature no matter what you do with that water cross over.

Edelbrock 7501: RPM Air-Gap Intake Manifold 1955-86 Small Block Chevy 262-400 | JEGS

Here is a picture of my motor with an Indy air gap. With a digital thermometer the intake is no cooler than the heads below it. Now if you have a exhaust crossover yes the center of the intake is hotter in the center under the carb. Doing a eliminator gasket set is all you can do to benefit heat exchange from the exhaust temperature.

Steve 050 - Copy.JPG
 
When you are at RPM the cold air coming through the venturis cool the aluminum intake but at idle the aluminum sucks the heat out of the motor and warms back up.
 
Note how these dual quad tunnel rams have the water separate and away from the runners completely. Your dual plane has the draw back of being low and on top of the engine blocks hot oil from under it and the water flowing through the front.

Re route the water up front if you can cut and weld to a floating thermostat housing and out a oil shield under the intake.

That’s as good as it’s going to get with an OE intake.
2CD7A450-B08F-4980-8DAB-2BEAAD0068AC.jpeg
3DA224F7-F5FE-46A0-92E2-26AFB9EDB65B.jpeg
 
Richard Sweet said:
I'd like to start this thread discussing water flow through intake manifolds. For various reasons, we might alter our I.M.'s and those gaskets.
For example, on my 4 barrel, 273, I used a gasket without a passage for the exhaust heat riser into the I.M. because I was getting carb boil, even with a 1/4" insulator gasket under the carb. Now the center passages are very cold while the end passages still get warmed by the water flowing through the I.M..
I think I've heard of I.M.s with water flow through the heat riser passage, which sounds like a good idea. Not too hot and not too cold. So how could I modify my cast iron I.M. to accommodate this better idea?
Related discussion welcomed.
Thanks, Richard
Click to expand...

Here in Michigan i have seen people use the block off gaskets and drill small holes in gasket for the heat..
 
rumblefish360 said:
Note how these dual quad tunnel rams have the water separate and away from the runners completely. Your dual plane has the draw back of being low and on top of the engine blocks hot oil from under it and the water flowing through the front.

Re route the water up front if you can cut and weld to a floating thermostat housing and out a oil shield under the intake.

That’s as good as it’s going to get with an OE intake.
View attachment 1715419018 View attachment 1715419019
Click to expand...



What does the sheet metal intake fit? I need that top you have on the bottom intake.
 
AJ, Did you mean to quote me or Lonnie?
I have considered putting a small hole in the I.M. gaskets for the exhaust passages into the I.M.. That would give more heat to it than with total blocking.
 
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Richard Sweet said:
AJ, Did you mean to quote me or Lonnie?
I have considered putting a small hole in the I.M. gaskets for the exhaust passages into the I.M.. That would give less heat to it.
Click to expand...


I'd be worried that once you open the hole it will continue to open up.

I'd be much less worried about temp issues at idle. I'd be more concerned what the temps are loaded. That's when the heat really matters.
 
yellow rose said:
I'd be worried that once you open the hole it will continue to open up.
Click to expand...
If the heat riser is working, the exhaust back pressure will blow the hole bigger eventually. If you try to block the passage with a gasket, it eventually burns thru the gasket too. You do not need all that heat in the intake manifold unless you live somewhere really cold.
 
Richard Sweet said:
AJ, Did you mean to quote me or Lonnie?
Click to expand...

I meant you,lol, Yeah I messed up
Assuming no headers;
If you put an IR gun on the manifolds at the ports, with a stock cam and proper ignition timing, and at idle, I think you are gonna find the temps at the exhaust ports is gonna be ~350*F or less. Some ports could be closer to 250*

Now,If your heat crossover was still operational, And the oil-shield underneath the plenum was NOT full of coke,then you could shut the engine off,whack open the secondaries and shoot the plenum floor. And I haven't tried it, but I am pretty sure it will be less than 240*F ... cuz if it was 240*F, or more, it would be heating the oil to the point of smoking; and the PCV would be inhaling that smoke, and it would be condensing on the back of your intake valves and plugging the ports up. Since you didn't mention this, Ima thinking the temp is below 240, maybe closer to 200/220 or so.
Now, when you put it in gear and start blasting down the road, if the heat-riser is working right that crossover is not gonna see a lotta action, because; a) the heat-riser is wide open, and B) the exhaust system is gonna be under a bit of pressure, keeping the shuttling to a minimum. And so the temp will be fairly stable and low, cuz additionally,the incoming fresh air is gonna cool that plenum off some, by process of evaporation.
But if your carb is inhaling hot underhood air that is being heated by the radiator and the exhaust manifolds, well put a thermometer in there and see how hot it's getting.

Now, if that airgap under the plenum, between the intake and the splash-shield is full of coke, then that coke, with a closed heat-riser,and a functioning crossover will become a heatsink, keeping your intake plenum hot all the time.
But with a blocked crossover, it will just maintain about whatever the water is doing same as what the iron intake is running at.
The bottom line is that the iron intake, with a NON-fuctioning system is only gonna run maybe 20/30* or so cooler, at or near idle and at PartThrottle, than if everything was working right.
BUT
You can reduce your inlet air temp from 200 or more degrees, to ambient by ducting some fresh air to the carb. That's probably more than a 100*F difference, maybe as much as 150*.
The lightest compounds in your gasoline want to evaporate at or near 85/90*F. Great for cold starting. Not great when you shut a hot engine off, and the carb is surrounded with hot air that is at or near 200 to 300.
 
block off the crossover with a common blanked gasket, or some thin metal and tap the port ends, run water through them. Older aftermarket intakes had EGR bosses cast in. Perfect place for a coolant tap. 66/67 273-4's had this too.
001.jpg
 
Everyone, my original description was incorrect. I apologize.
After actually touching the I.M., I determined that there is not a temperature difference of the runners.
With my exhaust cross over ports blocked on the I.M. and the engine warmed up, the temperature by touch, close to the carburetor, at idle, the runners to all cylinders is about 45*F (This is incorrect; see later measurements with an infrared gauge in post #28.)

I guess I got worried about something that I imagined in my mind.
Please accept my apology.
 
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Richard Sweet said:
Everyone, my original description was incorrect. I apologize.
After actually touching the I.M., I determined that there is not a temperature difference of the runners.
With my exhaust cross over ports blocked on the I.M. and the engine warmed up, the temperature by touch, close to the carburetor, at idle, the runners to all cylinders is about 45*F.

I guess I got worried about something that I imagined in my mind.
Please accept my apology.
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If you don't have a temp gun harbor freight has them really cheap. Seems from your post you are using the touch method.
 
No worries. It is a valid idea to approach and discuss.
There is HP in cool intake runners and the idea was a good one to talk about and discuss. Now others can ether rest at ease or look to there own equipment and tinker around.

Richard Sweet said:
Everyone, my original description was incorrect. I apologize.
After actually touching the I.M., I determined that there is not a temperature difference of the runners.
With my exhaust cross over ports blocked on the I.M. and the engine warmed up, the temperature by touch, close to the carburetor, at idle, the runners to all cylinders is about 45*F.

I guess I got worried about something that I imagined in my mind.
Please accept my apology.
Click to expand...
 
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