Intake Manifold - Installation
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Joined: Dec 2001
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From: Raleigh NC
Intake Manifold - Installation
I'm half-way through the project of fixing the intake oil leak. Cleaning everything.....mating surfaces, bolts, threads, etc.....At this point I have a few questions I knew I could count on you folks to answer.....
Particulars - '86, Cast Iron Heads
Questions:
1. Intake Gaskets - Restricted rear ports or not? The old gaskets were not restricted....the new set of Fel-Pro's (MS93317) ARE! Which is correct?
2. Threadlocker for intake bolts - Permatex Red, Blue, "242", etc...Which is correct?
3. Plenum and runner Gaskets - RTV Sealer or "Dry"?
Thanks in advance for the help....
RJVette23
Particulars - '86, Cast Iron Heads
Questions:
1. Intake Gaskets - Restricted rear ports or not? The old gaskets were not restricted....the new set of Fel-Pro's (MS93317) ARE! Which is correct?
2. Threadlocker for intake bolts - Permatex Red, Blue, "242", etc...Which is correct?
3. Plenum and runner Gaskets - RTV Sealer or "Dry"?
Thanks in advance for the help....
RJVette23
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
RJ, The only 85 intake job I did had rear block off in gasket. I think it was oem. Car had 18k. Hopefully someone else will chime in on this. I am only 90% sure. The intake bolts go into lifter valley and coolant passages. I use liquid teflon on these. Use your favorite sealer on these but no locktite. The throttle body and runner/plenum gaskets go on dry.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Though you could use Permatex #2 gasket sealer on the intake base bolt threads.
I did the same job earlier this year and would strongly recommend that you roughen the front & rear engine lands with say 40-grip sandpaper as well as the mating surfaces under the intake base. In addition it wouldn't hurt to divit these two mating surfaces to aid in adhesion.
I used a very thin layer of black RTV around the intake base gaseket water passages and two heavy beads on the front & rear engine lands.
I simply mention these extra precautions as my first attempt to seal the front & rear lands failed and I chased an intake oil leak for months, thinking that I had sealed the lands well.
Good luck with the project.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
After finding a manifold end seal leak, due to an insufficient bead of RTV, I dry fit the manifold, WITH gaskets, but without any sealant. I then eyeballed the end seal gap to get a feel for the amount of RTV that was going to be required to "fill the gap". Way too much can leave some floating around inside the engine. Too little can have you doing it over, as I had to. If your are going to err, go for a little too much.
RACE ON!!!
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
The rear ports don't go anywhere, so your gaskets are ok. Take a peek at your intake base and you'll see what I mean.
Use silicone rtv around your water passages. Also, run a 3/16" bead of black rtv on the walls front and rear, and partway up the head. DON'T use the gaskets they give you for those sections.
Make sure to follow the torque sequence also.. and its recommended to come back and retorque everything after the rtv sets up.
Use silicone rtv around your water passages. Also, run a 3/16" bead of black rtv on the walls front and rear, and partway up the head. DON'T use the gaskets they give you for those sections.
Make sure to follow the torque sequence also.. and its recommended to come back and retorque everything after the rtv sets up.
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Instructor
Joined: Jul 2004
Posts: 137
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From: CT
I recently replaced my '86 intake gasket with iron heads. Original gasket rear water passages were restricted, replacement NAPA gaskets (MS15315W) were not and I didn't worry about it. Had some concerns with the EGR passage between head and intake and DID block like the original gasket since the '86 has an external EGR tube. Used Permatex #2 for intake bolt threads and dry on the plenum/runners.
http://forums.corvetteforum.com/showthread.php?t=879079
http://forums.corvetteforum.com/showthread.php?t=879079
