Intake manifold has gap

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Aug 23, 2013 | 04:22 PM

Wolfavenger90

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Joined: Dec 2009

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From: Fruitport

Intake manifold has gap

I'm rebuilding a 351m for a buddy. It's original out of a 1978 f150. Neither the block nor the heads were decked at the machine shop. It is a new edelbrock 2171 performer intake. I have tried installing it with edelbrock gaskets and now just the valley pan. My problem is no matter what there is a gap at the front and rear valley bridge. Probably about 1/4 inch. The old intake was an egr intake the new one is none egr. All of the bolts line up and torque down.

My questions are is there a difference between egr and non egr in how it fits the block? And is this gap considered normal?

Thanks for any help.

Aug 23, 2013 | 05:55 PM

HIO Silver

Fleet Owner

Joined: Dec 2009

Posts: 20,678

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From: NorCal

Are you referring to the mating surface of the manifold to the front and rear of the block? The "China Walls"?

If so, then a gap is typical and would be taken up by the cork or rubber gaskets. Most builders will throw them away and lay down a thick bead of RTV. Consider dimpling the china walls with a punch so the RTV has something to hold on to... ala

Aug 23, 2013 | 06:05 PM

Wolfavenger90

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Joined: Dec 2009

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From: Fruitport

They are already dimpled. I started out with just rtv and that barly touched the intake. So I cleaned it up and used rtv and the rubber ends. Still too much gap for my liking. Last I cleaned it up again and went metal pan and rtv. Still doesn't seem right. I will snap a pic and upload it when I can.