Q: Attaching lower intake manifold to 3.8L block... - TCCoA Forums
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post #1 of 3 (permalink) Old 09-09-2012, 02:15 PM Thread Starter
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Q: Attaching lower intake manifold to 3.8L block...

I'm putting together my spare engine and I had a question for you folks
I know I should have paid more attention to my friend who was helping with the splitport upgrade so as a backup plan, I thought I should just throw up a quick post here.

The felpro intake manifold gasket kit I purchased for my spare block came with 2 molded rubber shapes that clearly fit between the heads (already bolted to the block) at the front and back of the "valley".

From what I saw when my friend was bolting down the manifold (I was messing with the fuel rail), you need to use some RTV to insure that the seal is complete.

Q: How much RTV do I need to use before bolting down the lower intake manifold? I know you need to use it at each end of the rubber pieces where the block would meet the intake manifold and the heads (that's what the EBSCO ARRC manual says) but I didn't see any comments in my Ford manual about using more RTV than that (i.e.: do I also need to run a bead underneath each rubber piece between the rubber piece and the block or a bead over the rubber between the rubber piece and the intake manifold as well?)

I'm pretty sure I remember seeing more RTV being put down by my buddy than just at each end and there was RTV that I scraped away off the block and the intake manifold BUT I didn't find or discard an original rubber piece when I first took the intake manifold off the engine.

Thanks in advance for your advice.

PS. As soon as I finish buttoning up my splitport project (this spare engine is a side project to entertain me while I wait for some more parts to come in), I'll be sure to post up a more thorough DIY that compiles all the advice I've received from you helpful folks.

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post #2 of 3 (permalink) Old 09-09-2012, 02:47 PM
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The RTV only goes between the heads / block / gaskets right in the corners. ( I usually put a dab in each corner, set the gaskets, and put another dab on top after the intake manifold to head gaskets are installed before the lower intake goes on )

There are two different style gaskets to the heads, Ford upgraded to thicker gaskets on the 96+ Heads, and they have two extra bolts with a smaller diameter 6mm vs. 8mm for the early style - the intake manifold itself was made a little thinner to accomodate this ), luckily they have studs that go into the heads to hold them in place during installation.

A lot of people run it on the top and bottom of the gaskets though, but the Fel-Pro instructions say its not necessary. It wont hurt anything if you do RTV them fully.
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post #3 of 3 (permalink) Old 09-09-2012, 02:52 PM
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I only do it to the corners to prevent seepage during expansion/contraction. To keep gaskets from moving during installation I use the gasket adhesive spray on almost any gasket I'm worried about moving.

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