Intake Manifold Gasket Installation
Thread Starter
Racer
Joined: Jul 2007
Posts: 444
Likes: 0
From: Roselle IL
Intake Manifold Gasket Installation
I installed my heads this weekend and dry fit the intake (Performer RPM). I am using the Fel-Pro Black intake gasket. I have quite a bit of clearance along the back rail, but only have .025 clearance on the front rail. The manifold appears to have a straight and solid fit with each of the heads.
I don't know how much these gaskets will compress. Will I be ok with this clearance? I can't have the manifold touch this front edge, of course. I intend to use RTV instead of the cork gaskets provided here.
Thanks.
I don't know how much these gaskets will compress. Will I be ok with this clearance? I can't have the manifold touch this front edge, of course. I intend to use RTV instead of the cork gaskets provided here.
Thanks.
Drifting
Joined: Oct 2005
Posts: 1,331
Likes: 479
From: Appleton Wisconsin
Did you have your block or heads resurfaced, if they didn't set the machine up right your surface may be tapered. With the RTV you should be ok if not you can have the manifold resurfaced.
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
dont be scared to load up a heap of sealant along the front and back edge. more than you think and especially in the corners cause this is where alot of them leak. let it squeeze out and cut it off later when it dries. i would only use felpro gaskets as well and think the blue ones are best that that only go over the head-manifold face.
Thread Starter
Racer
Joined: Jul 2007
Posts: 444
Likes: 0
From: Roselle IL
Thanks for the input. Do think the composite gasket will crush so much as to eat up my .025 clearance? I am afraid if the metal touches, I won't have enough crush on composite gasket between the manifold and heads.
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
im not following completely?? so your gasket runs along the front and back edge of the motor as well as on top of the heads. is it one piece? i have only used felpro blue that sit on the heads and use rtv hi temp silicon on the front and back edges.manifolds are not very TRUE sometimes so that might be explaining your difference in heights from front to back.
Thread Starter
Racer
Joined: Jul 2007
Posts: 444
Likes: 0
From: Roselle IL
I am using the standard gaskets between the manifold and head, no problem here. the spacing at the front of the manifold, between the manifold and the block is thin (.025). I assume the gaskets between the manifold and the head will crush as I tighten them. As they crush, the space between the manifold and the head will shrink. I am trying to be sure that the manifold doesn't actually hit the block up front.
As I think about it, the gasket is only .060, so it would have to crush at least half to take up the .025, so I should be safe as it can't crush that much with 25 ft/lb.
Thanks.
As I think about it, the gasket is only .060, so it would have to crush at least half to take up the .025, so I should be safe as it can't crush that much with 25 ft/lb.
Thanks.
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
ok i understand . i cant really comment with accuracy because the gaskets i have always used are about thick as a large key side on and they are only torqued down by the manifold bolts very lightly. i cant remember the Nm torque but i know it isnt much. so i guess thats why i always have a larger gap at front and back of the manifold. if yours are more like a normal gasket material i dont think they will compress too much but i would recommend putting some of the hi temp rtv around the water jackets for extra security and be sure to follow the torque down pattern.
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Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Use enough RTV to seal the intake but do not use too much.
I do agree that you should go a bit heavier at the 4 corners where the front and rear endrails meet the heads as this is a common leak point.
Here is a pic from when I was redoing the motor out of my '78:
you can see that the RTV bead is not excessively large but it's more than enough to seal the intake. I use this method each time on both my '78 and my '65 and never get leaks from the intake.
You can also notice that i've got the bead a bit heavier in each of the corners.
Extending the RTV bead to go around the outside water jackets as you can see in the pic also helps.
It's best to put the RTV down in one continuous bead rather than having it broken up
Drifting
Joined: Apr 2006
Posts: 1,911
Likes: 2
From: gold coast queensland
barryK i put down about the same amount of sealant as you . i probably do a little bit more than you so i guess my idea of " heaps " and yours are slightly different but your picture is good and worth a thousand words. the only thing i do different apart from the slightly heavier amount of sealant is i run the bead more towards to outside edge of the motor so that when it does squash down it squeezes out of that edge and not into the motor.i guess it depends on your manifold when you dunmmy fit it as to how much gap there is.i would be more concerned about my gaskets and silicon not sealing against that blue paint and where it might go when the oil breaks it down. shouldnt the gasket surface be bare metal clean?
Last edited by gingerbreadman1977; Apr 27, 2008 at 07:58 AM.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
gingerbreadman, I usually try to get my RTV bead in the middle of the endrails but yeah, this time I did seem to run it more towards the inside. Still had some seep out the outside though but not much. I wait 5-10 minutes for the RTV to set up before dropping the intake and that helps.
You are probably correct though about our definitions of 'heaps" of sealant. When I read your post I had visions of a HUGE overflowing bead of sealant that was 3-4 times too much. That was the point I was trying to get across was that too much sealant CAN be a bad thing so someone shouldn't get too carried away putting it down
You are probably correct though about our definitions of 'heaps" of sealant. When I read your post I had visions of a HUGE overflowing bead of sealant that was 3-4 times too much. That was the point I was trying to get across was that too much sealant CAN be a bad thing so someone shouldn't get too carried away putting it down
