Classic Engine Tech 1967 - 1981 Engine Related

Intake Manifold Gaskets?

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Old Mar 14, 2007 | 03:15 PM
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Question Intake Manifold Gaskets?

Hello. I have a 1979 Z28. My question is: Do I glue both sides of the gaskets to the heads/manifolds?

Thanks
Old Mar 14, 2007 | 05:41 PM
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Just around the water passages, front and rear, and instead of the front and rear rail gaskets, I lay down a bead of silicone instead. If you haven't purchased yet, consider the Fel Pro Printo Seal type. Comes with a built in sealing ring around each port:

http://store.summitracing.com/egnsea...5&autoview=sku
Old Mar 14, 2007 | 08:46 PM
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thanks.

one more question: the intake manifold gaskets come with a square steel piece in between which combine together with a hole in the middle. what is this called? and, which side should face the engine?
Old Mar 15, 2007 | 09:09 AM
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It's the exhaust crossover restrictor. Also helps protect the gasket from burn thru. In stock applications there is a valve with a weight on it on the outlet of the passenger side exhaust manifold. It closes at part throttle and forces exhaust thru the exhaust crossover in the intake manifold and out thru the driver's side. The exhaust heats up the bottom of the intake and helps vaporize the fuel in cold conditions.

Those exhaust manifold valves are hp killers, especially if they corrode shut. If I see one on someones car, and they can't be talked into getting rid of it, I get an overwhelming urge to wire them up in the open position.

I can't tell you which side faces the engine cause I never use those restrictors. Instead I block the crossover passage off on both sides, keeps the heat off the intake for a denser air/fuel charge and, hopefully, more HP. I make the block offs from thin steel shim stock, but I think you can buy them at speed shops ready made. Some performance gasket sets come with them. A lot of aftermarket heads don't even have the crossover passages.

Of course if you have a frozen shut exhaust manifold valve, blocking the crossover would leave no where for the passenger side exhaust to go... I run headers so no problem there.
Old Mar 18, 2007 | 06:04 PM
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once more?

Thank you.

When I put the head bolts on, there are 9. What is the sequence for putting on these bolts to the heads and the intake manifold?
Old Mar 19, 2007 | 10:58 AM
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I'm not sure which bolts you're referring to. There are 12 intake manifold bolts, 17 bolts per head on the sbc. If it's the intake bolts, you start torquing them at the center of the intake and work your way out in a circle pattern. Snug them up the 1st time, then torque them to down on the 2nd pass. Retorque after the engine has been brought up to temp a couple of times, when the engine is cold. They are supposed to be torqued to 25 ft/lb, but I've always just used a box end wrench and torqued by feel.

The one thing you must look out for is that 2 of the bolts at the center (one per side) line up directly over a pushrod. If sometime in the engine's past some one replaced the stock lenght intake bolts with some that are longer, you can bind up the pushrods at those 2 spots.

Last edited by angel71rs; Mar 19, 2007 at 11:01 AM.
Old Mar 19, 2007 | 10:01 PM
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Smile

Thanks again....I'm sorry, just one more:

In the middle of each head, there are 8 bolts (350 engine), and on the side towards the exhaust manifold, how do you torque those down? Do you have a pic for reference?
Old Mar 20, 2007 | 09:05 AM
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Here you go:

http://www.geocities.com/meanracing/...formation.html
Old Mar 21, 2007 | 12:54 AM
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Smile

Thank you! You are a life saver!
Old Mar 24, 2007 | 01:42 PM
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Question: On the pic you linked, which side of the head is the front and which is the back?
Old Mar 24, 2007 | 05:45 PM
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Doesn't matter. Just start at the center and work your way out, passenger or driver side.
Old Apr 6, 2007 | 08:47 PM
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Wink

Hi! Did you miss me? Listen, on my exhaust manifold, I have 1 gasket. Which manifold does the gasket attach to?
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