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Cylinder head - intake manifold question

pearljam724

pearljam724

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I removed my intake manifold which is an aftermarket Edelbrock. I have a 360 small block. On my heads I have 2 water jackets on the front and 2 on the rear. They are number matching heads. The Edelbrock performer RPM intake manifold only has 2 water jackets on the front, but doesn’t have the holes in the rear, why ? And what does this affect ?
 
The water ports are blocked on the intake for proper water flow inside the engine, and the heads are open on both ends so that they can go on either side.
 
69Bee said:
The water ports are blocked on the intake for proper water flow inside the engine, and the heads are open on both ends so that they can go on either side.
Click to expand...
Oh, thank you. So you’re saying the heads are designed to allow an intake to be turned around ? If not, why even have the ports on the firewall end of the heads ?
 
No, the heads can go on either side of the engine, the intake only one way. The water ports are only open on the front, and blocked to the rear.
 
The heads are designed to be Right or Left being only one part number, meaning interchangeable from side to side.
 
Lefty71 said:
The heads are designed to be Right or Left being only one part number, meaning interchangeable from side to side.
Click to expand...
Makes very good sense now, thank you both.
 
As mentioned, the heads are cast to be used on either side of the engine.
The water flows from the lower radiator hose into the pump, and the pump pushes the water into the front of the block.
The head gasket actually blocks the water from going to the front hole of the cylinder head, and makes the water flow to the back of the engine block, and then into the back of the cylinder head from the bottom. The holes at the back of the cylinder head top are blocked off by the intake manifold to make the water flow from the back of the head to the front of the cylinder head, and then into the front of the manifold. When the water is hot, the thermostat opens and the water flows into the top of the radiator.
 
Do you guys prefer to use a thinner or thicker manifold gasket ? My old set is nearly twice as thick as the one I just received new. New is Felpro. I’m thinking thinner side gaskets might be better as this will close the gaps under manifold in front and back and allow front and back to seal better ? My heads are original cast.
 
Drop the intake on without gaskets and check the location of the head bolt holes to the intake holes.
If the head hole is partly covered by the upper part of the manifold hole, use the thicker gasket to move the intake up.
If the head hole is closer to being centered, use a thinner gasket so the manifold does not move up as much.
 
451Mopar said:
Drop the intake on without gaskets and check the location of the head bolt holes to the intake holes.
If the head hole is partly covered by the upper part of the manifold hole, use the thicker gasket to move the intake up.
If the head hole is closer to being centered, use a thinner gasket so the manifold does not move up as much.
Click to expand...
Good tip, I appreciate it. Maybe that’s why the seal let loose. Who ever previously put the manifold on. Used a thick set, no cork on front n back. Only silicone in front and back. It never leaked shortly after I bought car. But, it was several months before I started to drive it consistently at higher rpms in warm weather. Until then, I was just putting around my neighborhood. It let go on a 70 mph interstate, climbing steeper inclines.
I knew it, when occasionally I saw white smoke in mirror only at higher speeds. At least, that’s what I’m thinking. Hope I’m right
 
On my 360, the heads and block were milled, and the intake sat so low the ends were almost touching. I only used some RTV on the ends, no room for the end gaskets.
Anyhow, always check that the intake fits, aligns with the heads. I have had to cut the intake surface down on my 400 block because the intake sat too high.
I never had an intake the sat too low, but using thicker gasket should solve that.
 
451Mopar said:
On my 360, the heads and block were milled, and the intake sat so low the ends were almost touching. I only used some RTV on the ends, no room for the end gaskets.
Anyhow, always check that the intake fits, aligns with the heads. I have had to cut the intake surface down on my 400 block because the intake sat too high.
I never had an intake the sat too low, but using thicker gasket should solve that.
Click to expand...
Being I’m taking the same intake off the same engine while still in the car. I shouldn’t have an issue with fit. As long as I choose the right thickness side gaskets. Hopefully the previous ones were too thick. I won’t know anything until it’s cleaned up better and test fit. I like the idea of using the cork gaskets if I can.
About a month ago for no damn apparent reason. I thought I would check the bolts torque. Turned out they were about 15 pounds too loose. I tightened them in proper sequence to factory torque spec and that’s when I started having leaking problems. When I tightened them down a little more. I think the silicone broke loose. At least that’s what I’m hoping. That or it’s the oil pan. Cause I really don’t want to venture into a main seal replacement. I’ll know more as I eliminate areas.
 
I toss the end rail gaskets, and just use RTV instead on all of the motors I build.
 
69Bee said:
I toss the end rail gaskets, and just use RTV instead on all of the motors I build.
Click to expand...
Thanks for sharing. Seem most people do the same. Do you let it partially dry before you torque it down ? Dry completely before torque ?
I know manufacturers state to immediately mate surfaces, finger tight nuts or bolts. Wait an hour, torque to spec. But, I’ve had no issues allowing a bead to completely dry on one surface then mating the 2 to spec.
But, this is my first intake manifold. So, I’m asking
I think my intake seal let lose when I further torqued someone else’s previous work I’m hoping
 
Last edited:
Squeeze, drop, torque... I ain't got time to wait that long...
 
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