Intake Manifold Gasket Question
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From: Friendship WI
Intake Manifold Gasket Question
I've got an '85 Coupe and am switching from the cast heads to a set of 113 heads off of a '90. I am wondering what intake gaskets I should use. If I look up the gasket for the 85, it shows both the coolant passages open for flow, but if I look it up for the 90, it shows the back coolant port on the gasket blocked off and just a small hole in it.
Which one should I order, and what is the point of the blocked off portion?
Which one should I order, and what is the point of the blocked off portion?
Race Director
Joined: Jun 2004
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From: WI
I've had a number of combos with and without that rear water passage and haven't found a difference. No issues either way. I've had combos with full open, full closed (for example my mini-ram intake combo has no crossover in the manifold at all), and with the small hole in the gasket. I've also had combos with the small rear coolant pipe at the back of the manifold and some without. Again with no issues either way.
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From: Overland Park Kansas
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SunCr has posted about this several times. I bet you can find posts if you use his userid.
IIRC, the point was to slow coolant flow in the rear of the intake. Supposed to increase heat transfer to the coolant IIRC. But many people have responded as Aardwolf....that their really isn't much (if any difference).
I chose the open gasket for my 383 setup (even though my '89 had the blocked passage from the factory.)
IIRC, the point was to slow coolant flow in the rear of the intake. Supposed to increase heat transfer to the coolant IIRC. But many people have responded as Aardwolf....that their really isn't much (if any difference).
I chose the open gasket for my 383 setup (even though my '89 had the blocked passage from the factory.)
Burning Brakes
Joined: Mar 2010
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From: Providence RI
whats the point of that rear coolant passage? My manifold has it blocked off but my stock intake had it in service.
I took the hose that used to go to it and plugged it and tucked it somewhere.
Should I go back to stock or just run it as is??
Mike
I took the hose that used to go to it and plugged it and tucked it somewhere.
Should I go back to stock or just run it as is??
Mike
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From: Overland Park Kansas
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I gave you the Cliff Note's answer above. The point was to slow coolant at the rear of the intake. Some engineer figured this would allow better transfer of intake heat INTO the coolant. Plus, they added that extra feed line from the heater hose over to the rear of the intake.
IIRC, water circulates from the top down in a motor AND goes out thru (out) that top heater hose first. So, that extra feed (thru the heater hose) should be the lowest temp coolant.
Also, I think the issue was heightened when aluminum heads went into production and concerns with intake/head gasket failures might go up.
By contrast, F-bodies -- with the same motor -- did not leverage this modification. Overall, I think it wasn't very effective. That's why few bother to reinstall the restricted rear water port intake gaskets.
IIRC, water circulates from the top down in a motor AND goes out thru (out) that top heater hose first. So, that extra feed (thru the heater hose) should be the lowest temp coolant.
Also, I think the issue was heightened when aluminum heads went into production and concerns with intake/head gasket failures might go up.
By contrast, F-bodies -- with the same motor -- did not leverage this modification. Overall, I think it wasn't very effective. That's why few bother to reinstall the restricted rear water port intake gaskets.
