Why would my intake not be sealing properly to the heads?
11-10-2006, 01:47 PM
#1
Why would my intake not be sealing properly to the heads? This is the second time the intake gaskets have started to leak on my vette. After I replace them it runs fine for a few months and then starts stuttering like a premature rev limiter from the unmetered air.
I've converted to the LS6 steam tube and there is adequate clearance under the manifold...why isn't it sealing properly? The heads are 98 style stage II ARE's milled .30. I'm guessing maybe the milled heads are causing an uneven mating surface for the intake and thats why I keep going through gaskets? Is this possible? I've never heard of anyone machining an ls6 intake before.
Where do I go from here?
I've converted to the LS6 steam tube and there is adequate clearance under the manifold...why isn't it sealing properly? The heads are 98 style stage II ARE's milled .30. I'm guessing maybe the milled heads are causing an uneven mating surface for the intake and thats why I keep going through gaskets? Is this possible? I've never heard of anyone machining an ls6 intake before.
Where do I go from here?
11-10-2006, 03:24 PM
#5
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I had to torque the **** out of mine to get it to seal as well as thicken all the gaskets. I don't normally post this, because what works for me may or may not work for you. Wouldn't want to be responsible for you torquing your manifold to pieces.
11-10-2006, 03:44 PM
#7
What kind of torque specs are we talking? I might get a set of ARP bolts and bump the torque up on them a little bit if it solves the problem. And how did thicken the gaskets? I can see oil all around the intake ports on my heads so I know something out of the ordinary has to be done.
Any idea if a fast intake would help with this problem? I've been considering upgrading to the 90mm intake/TB combo. If it helps this sealing problem its just that much more tempting.
Any idea if a fast intake would help with this problem? I've been considering upgrading to the 90mm intake/TB combo. If it helps this sealing problem its just that much more tempting.
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11-10-2006, 04:00 PM
#8
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I just pulled mine out last night and that was a pain in the ***. I cant imagine taking it on and off all the time because of it leaking. I had my heads milled 10 thousandths just for this reason. I had heard of some peoples intake not sealing right after milling to thirty. Good luck.
11-10-2006, 04:14 PM
#9
WIth my fast, I got some threaded rod and torque to lower portion down to line it up perfect (mainly for porting). THis is great on the engine stand but may be a bitch once on the car.
https://ls1tech.com/forums/generation-iii-external-engine/525974-fast-90-intake-owners-have-you-tried.html
https://ls1tech.com/forums/generation-iii-external-engine/525974-fast-90-intake-owners-have-you-tried.html
11-10-2006, 04:28 PM
#10
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I don't know that milling 30 would make the intake not seal. Does it always leak in the same place? I would remove it, mark the heads with dry erase marker or mark the manifold with chalk or something that will leave a clear impression, then lay it on there. See if the bottom of the gaskets are hitting and tops aren't, or vice versa - that would indicate a change in geometry of the heads and some mild shaving will probably fix it. If the fronts or backs are hitting then you may have a bad manifold. Start by seeing where your problem is.
11-10-2006, 07:21 PM
#11
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Speaking of manifolds does anyone have a picture of how the two wires are suposto be routed under the manifold? I guess what im trying to say is when you put the intake back on how do the front and back wires in the middle of the valley cover go? Maybe that is why your intake is not sealing right. And i wanted to know so i dont run into the same problem. (Did not payatention how they were when i took it off)
11-11-2006, 01:27 AM
#12
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to thicken the gaskets, lots of black high temp RTV, a few shims, and patience. By the time you're done, you should be able to swap a manifold in 30 minutes.
In short:
Apply mold release agent to the gasket channel
inject an even bead of RTV (pick up a couple of oral syringe's at a local pharmacy)
install the gasket(s)
install the manifold with 0.015" shims (this will allow the gaskets to move into proper position with out squeezing all the RTV out)
let dry for 24 hours
Pull the manifold
Remove gaskets
Scrub it till hell wouldn't have it
install gaskets
install manifold
test for leaks
Not sure a Fast90 would help you, as it has but-load more gasket material to thicken than an LS1/6.
A good point was bought up in a previous post - make sure the knock sensor wiring is not your problem.
As far as torque specs, start with the factory specs and increase 1-2 inch-pounds as necessary. It really shouldn't take much (if any) more than factory specs if your geometry is correct.
In short:
Apply mold release agent to the gasket channel
inject an even bead of RTV (pick up a couple of oral syringe's at a local pharmacy)
install the gasket(s)
install the manifold with 0.015" shims (this will allow the gaskets to move into proper position with out squeezing all the RTV out)
let dry for 24 hours
Pull the manifold
Remove gaskets
Scrub it till hell wouldn't have it
install gaskets
install manifold
test for leaks
Not sure a Fast90 would help you, as it has but-load more gasket material to thicken than an LS1/6.
A good point was bought up in a previous post - make sure the knock sensor wiring is not your problem.
As far as torque specs, start with the factory specs and increase 1-2 inch-pounds as necessary. It really shouldn't take much (if any) more than factory specs if your geometry is correct.
