1999 4.0 OHV head job

[Ashton_1012]

whats up everyone. I am currently working on replacing the heads on my 4.0 OHV. I installed the heads and lower intake manifold last weekend, and because of time restraints I called my mechanic to come finish it.

He went out today and told me I was sold the wrong heads. He said the lower intake manifold and the heads are supposed to sit flush, and my lower intake manifold sits 1/8" lower. Is he correct that they need to sit flush? I ask because he has been wrong in the past, and I don't want to chase after a problem that isn't a problem. I bought these heads from a local Westbay Machine shop, who ordered the heads from the manufacture and did the core exchange for me. I won't be home for two days, otherwise I'd post the casting numbers. Thank you in advanced!

 

[RandomNerd2000]

I'm slightly confused as to what he means by flush, and I also didn't know there was more than one set of heads for a OHV? Your mechanic sounds wrong somehow to me.

 

[Ashton_1012]

I am not sure. He is saying the surface of the lower intake manifold needs to be sitting flush with the surface of the heads. There should only be one set of heads for this year, but perhaps I was sent heads for the wrong year.

 

[Ashton_1012]

He said, "The lower intake should be level with the heads for the valve cover surface and the intake is 1/8 th of an inch lower. I don't want to put it together like that it's gonna leak like a flowing river"

 

[lobo411]

IIRC there will be a slight gap--maybe 1/16"--at the junction between the lower intake manifold and the head, where the valve covers mount. When you install the valve cover gasket with standard gaskets, you're supposed to put RTV in *this area only* to bridge the gap.

The Fel-Pro PermaDry gaskets are designed to use NO RTV at all, but notice the design. They have a hard plastic/rubber area for the upper 15% that abuts the lower intake manifold, and a hard plastic/rubber area for the lower 80% that abuts the head. The 5% in the transition zone between the head and the lower intake manifold is just rubber--no hard plastic. That's because it needs to step up a little to meet the "lip."

Also, don't forget that the two pieces--the head and the lower intake manifold--are dissimilar metals with different thermal properties. I'm guessing that one reason it has that "lip" is to allow for the fact that the cast iron heads will expand less than the aluminum lower intake manifold.

This pic is from another thread on another forum, but it shows what I'm talking about. The area in the red box is where the head and lower intake manifold meet. On mine, there's a small 1/16" lip there.

https://www.ford-trucks.com/forums/...-replacement-leak-troubleshooting-w-pics.html