G body A/C or heater box modification

5one9

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Does anyone have a close up picture of a 1978-88 G Body heater or A/C box that has been cut for clearance of a 500 Cadillac? I'm just trying to get an idea of location and amount of material removal. One vendor claims to have an engine mount kit that uses the stock A/C box, but my measurements make that claim seriously questionable.

Any help appreciated prior to me just jumping into it.
 

Cadiac

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With my engine offset aprox 2.5” the rocker (stock) cover chafed the box. I made a hole in the box to accommodate the #7 plug wire. Lol 85 GP assuming all box’s identical?
 

5one9

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GP should be the same. I assume you mean offset toward the driver side?
 

Cadiac

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No to the passenger side to get the exhaust away from the steering column
You can remove the shaft from column to box and get one from a jeep wagoneer Will give a little more room
 

5one9

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If I moved my engine half that amount, the head itself would hit the box, without the valve cover.
 

Darius

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Don't you just love tight spaces??? NOT!!

bro. d
 

Cadiac

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Really? Mine is still on the same mounts 21 years later, but is gutted of everything for racing only. My stock rocker cover chafed the box
 

Cadiac

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I may have a video I can get a pic from???
 

5one9

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I may have a video I can get a pic from???

That would be cool. With my engine dead center, a chrome valve cover almost bolts on but not quite. If Caddy had mirrored the bolt holes like SBC you could flip the cover around and it would clear the box and have extra rocker clearance..........but they didn’t.......
 

5one9

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So, with the rockers installed (no pushrods yet) and the aftermarket chrome covers on, the covers sit flat on the head mating surface without touching the rockers anywhere. If I turn the covers around 180 degrees, I still have clearance at the roller end, even though it's the short side of the cover. A gasket will only help the clearance situation.

With the cover turned 180 degrees I also have about 3/8" of clearance between the cover and the A/C box at the closest point, which will barely decrease with gasket installed.

Here is the plan. I just bought a $35 set of black aftermarket covers identical in shape to the chrome ones. I will cut parallel with the mounting flange, up high before the curve on the cover's short side, all the way around the cover. Flip the top around, bolt it to an old head, and with a little body hammer work and my TIG or MIG, weld the tops back on. By moving the tall side of the cover to the intake side of the valve cover, there will be more than enough clearance at the adjuster screw for my 0.353" lobe lift.

It won't be the polished aluminum covers that I hoped to use, but no cutting of the fiberglass box to allow the A/C to be functional will be well worth it. I will update with pics as I proceed.
 
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5one9

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FB4A7445-4BE3-4F4E-9752-220F5FE2B8C9.jpeg Cut and flipped valve covers today. I have about 3/8” of clearance to the A/C box and plenty of rocker arm clearance at full lift. I’ll paint them with wrinkle paint to cover the imperfections.

Now on to the headers.
 
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