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Discussion Starter #1
Ok this should help end alot of the confusion hopefully. As JL as stress many times it's pretty easy to see where the RTV sealant has to go if you look at the gaskets. Also I have a picture of the crossover before and after the boss has been drilled/tapped.

Before


After


PI Vs. NPI gasket full view


PI vs. NPI gasket


PI vs NPI gasket again...


PI on top of NPI


Hope that helps...
 

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Discussion Starter #2 (Edited)
Just to make it even easier.. and to avoid the question.. here are pics of the gasket sitting on the intake...

NPI gasket on intake


PI gasket on intake


Per Greenbird's post.. this also should be noted... just figured I'd throw it in this post to make easier... this is the reason that you need the 02 coolant hose, the pre 99/PI intake hose won't work since the PI intake is deeper, the 02 hose routes differently. This is taken from a thread over on modular depot (credit due).

 

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I'm supposing the RTV needs to go around the water jackets on the ends? I never realized how close it is to the bolt and intake port. If not, where is RTV needed? I haven't ever used any RTV anywhere on any 4.6L intake install and havent had any problems. Thanks
-Rob
 

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Very nice. The coolant passage differenece isn't even worth mentioning. The intake port looks BETTER on the bottom left, and just a dab of RTV ont he top left and your good to go!

Just put it in the same thread, here is a comparision of the intakes to show why you need the coolant tube:

 

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Discussion Starter #5
Rob said:
I'm supposing the RTV needs to go around the water jackets on the ends? I never realized how close it is to the bolt and intake port. If not, where is RTV needed? I haven't ever used any RTV anywhere on any 4.6L intake install and havent had any problems. Thanks
-Rob
The first comparison is to show you that the water ports match up just fine.

The difference in the shape of the ports and how the NPI gasket seats against the intake is the reason for the RTV.

Again, this is for a PI intake, obviously the problem isn't there with a NPI intake.
 

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Formerly Fdawg97LX
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just wondering, whynot use the pi gaskets? it seems like they would seal everything up. just wondering cuz i'm gonna be doing the pi intake swap withint he next few weeks, i just bought one.

Frank
 

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Oh, you are discussing how to reshape the intake ports. At first I wouldve probably passed up the silicone idea. Let us know how it feels when you install.
-Rob
 

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Discussion Starter #8
fdawg97lx said:
just wondering, whynot use the pi gaskets? it seems like they would seal everything up. just wondering cuz i'm gonna be doing the pi intake swap within the next few weeks, i just bought one.

Frank
I don't know the definite answer on that one.
 

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Discussion Starter #9
Rob said:
Oh, you are discussing how to reshape the intake ports. At first I wouldve probably passed up the silicone idea. Let us know how it feels when you install.
-Rob

Not debating anything, just showing the difference in the gaskets and where you have to apply the RTV.

The gasket doesn't seat perfect against the PI intake and that is why you need to use the RTV sealant to make sure you have a good seal.

In every thread that has discussion about the PI intake swap, people are asking about the gaskets and why you need RTV. So I figured I'd post a bunch of pictures because it's pretty easy to see what needs to be done.
 

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Baddest N/A NPI in Canada
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The reason you use the NPI gasket is that the NPI heads have a larger coolant passage than the PI heads do! So if you use the PI gaskets, you will have to combat a coolant leak which is harder to seal than air!
 

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fdawg97lx said:
just wondering, whynot use the pi gaskets? it seems like they would seal everything up. just wondering cuz i'm gonna be doing the pi intake swap withint he next few weeks, i just bought one.

Frank
It's the coolant passage. See in his last pic in his first post, how the PI intake actually crosses over and practically goes through the coolant passage? Real easy leak there. Then there's the blind pegs (they align and keep the gaskets from moving around), which are on opposite sides of the intake port (see 1st vs 2nd pics)
 

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Hey Chris,
Thanks for posting the pics.
I am doing the same swap. With your gasket comparo I can see I will
use the NPI ones.

I think after a couple of us do this mod and the more we learn about it,
and more info can be shared, and the easier it will be to do the swap.

Hey I was wondering what size tap was that temp sensor?
That would be another good tip to post as well.

Good Stuff!!!
Steve 4.6
 

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Discussion Starter #13
Steve 4.6L said:
Hey I was wondering what size tap was that temp sensor?
That would be another good tip to post as well.

Good Stuff!!!
Steve 4.6
A 16mm 1.5 tap will thread in, but it's a tapered thread, so that really isn't the correct size. I took mine to a shop, they did it for $27.
 

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Formerly Fdawg97LX
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look at the pic below. this is where the rtv needs to be applyed, right? should i put the rtv on the gasket or on the intake itself or does it not matter? I'll be doin this swap in 2 weeks and i want to make sure i know exactly what to do. thanks.



Frank
 

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Discussion Starter #16
guitar maestro said:
chris once you put the RTV on the gasket/intake, how long till it cures to be able to bolt it on?
About 24 hours for a FULL cure..
 

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Formerly Fdawg97LX
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chrisnack said:


About 24 hours for a FULL cure..
so you put the rtv on the gasket and manifold the day before you plan to install it? i dont have the parts in front of me yea so some of my questions might have blatantly obvious answers so bear with me. thanks.

Frank
 

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Discussion Starter #18
fdawg97lx said:


so you put the rtv on the gasket and manifold the day before you plan to install it? i dont have the parts in front of me yea so some of my questions might have blatantly obvious answers so bear with me. thanks.

Frank
You need to bolt it on right away... the RTV takes a few hours to cure good, and mine says 24 for a full cure. You don't want the RTV to cure before the intake is on, that would definetely defeat the purpose.
 

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Yeah, if you let it cure when it's not bolted then it's pointless. I think you guys need to pick up a tube of RTV and just read the directions.

RTV=Room Temperature Vulcanization.

Vulcanization: treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold.

the correct tap for the coolant sensor is 3/8 NPT
 

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chris, can you tell me the part numbers on the 99+ coolant tube and the NPI intake gaskets. thanks.

Frank
 
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