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:1zhelp: :1zhelp: I AM GETTING READY TO PUT MY 390 BACK IN MY 67 GT CAT WITH A C6 TRANS AND POWER STEERING ,WHAT IS A EASY WAY IF ANY TO INSTALL THE HOOKER HEADERS IN THIS CAT .THANKS CATMANDO
 

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I have heard that you have to lay the headers in the engine bay, put the engine in part way, loosely bolt up the headers, then drop the engine the rest of the way, and tighten up. I have also heard of people taking the front crossmember out and sliding them in from underneath. whatever the mean of installation, I think it's gonna be a PITA. I will be doing the same thing in about 2 months!
bmaker
 

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Hooker headers will not seal properly on GT390 heads unless you plug the top two bolt holes in cylinders 1, 4, 5 and 8 on the cylinder heads. It is still a mismatch to some degree but works OK. Hold the header gasket up to the exhaust ports and you will see what the problem is.
 

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Here's how

This is a picture of the plug you need to make, four times. It is a 3/8 X 16 NC grade six bolt. I cut off a piece approximately 9/16" long and cut a slot off center to use as a screw driver insertion point.
 

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Here is the plug installed.....

Notice I have drilled and tapped a new hole in the head above the original hole which is now plugged. You don't have to do this unless you want to use all 16 bolt holes in the Hooker headers.
 

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Why it would leak without the plug.....

Here is a picture of a used Hooker Super Comp FE gasket (used) on the same exhaust port. Notice the edge of the bolt peeking out into the area of the header opening? You get four leaks this size if you don't plug the holes.
 

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I hope Catmando hasn't spent all weekend installing the motor........
 

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I know this is sorta off topic but:

Royce...do the 390 FPA headers require the same modification? My 68 has the original 2v heads. Are they more difficult to install?

Ken
 

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No, the FPA's are available with the correct bolt pattern. They are also a tri - Y design which gives better ground clearance. As for ease of installation, expect it to still suck. There is not much room.
 
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