milled heads and valley pan

5wndwcpe · Apr 26, 2020

Fellas,
I have a '68 383 that have had the heads milled .040 (deck surface) and the intake milled .050 to match. The issue I have is the valley pan bolt holes are (unsurprisingly) way off.

Victor-Heinz and Fel-Pro both have this issue. Is there another choice for a better fitting pan out there or should I just hog out the holes ?

What have y'all done ?

Bighead440 · Apr 26, 2020

I have laid a DULL chisel across the corners of the pan where it meets the block China wall and the cylinder head joint, and given it a smack (all 4 places). You don't want to cut it, so go easy. Then remove and put the usual silicone ball to seal it there, before adding the stiffening plates and bolts in. The RIGHT way is have the China wall trimmed with a Bridgeport when getting the block deck cut. Too much milling can't be dealt with this way (the chisel trick) and the port section can be cut away from the pan and use (overlapped at the bottom over the remaining pan) composite side gaskets from Mr Gasket/Hughes/etc.

1 Wild R/T · Apr 26, 2020

Don't hog the holes, port/gasket alignment will suffer...

Big Head 440's chisel sounds interesting, might combine it with my method & have even better results..

My method has always been before installing the end rail bars I start bolts in the holes that attach the manifold without the manifold... If your careful you can use a screwdriver in the next hole over to pull the pan down... once all eight bolts are started I install the end rail bars & let it sit for a couple hours to assume the shape then I remove the bolts & install the manifold... Sometimes you have to play around but I've always been able to get it together...

Adding the dull chisel to force the gasket tight into the corners can't hurt...

BSB67 · Apr 27, 2020

5wndwcpe said:
Fellas,
I have a '68 383 that have had the heads milled .040 (deck surface) and the intake milled .050 to match. The issue I have is the valley pan bolt holes are (unsurprisingly) way off.

Did you have the intake milled, or the intake side of the head milled?

5wndwcpe · Apr 27, 2020

BSB67 said:
Did you have the intake milled, or the intake side of the head milled?

The intake was milled.

RemCharger · Apr 27, 2020

383 ,heads milled .060, intake face of head milled to match, dull chisel trick . Did this 20+ yrs ago and has worked great.

Don Frelier · Apr 27, 2020

It works best to mill the side of the head .0123" for every .0100" off the chamber side of the head.
By milling the intake you now have to mill every intake you want to try, and then they are messed up for any other "standard" geometry motor.
But yes the valley pan will still want to sit higher, especially if you stick with a thin steel shim gasket.

BSB67 · Apr 27, 2020

RemCharger said:
383 ,heads milled .060, intake face of head milled to match, dull chisel trick . Did this 20+ yrs ago and has worked great.

But this gives a different result than milling the intake. He'll have an alignment problem that you wont have when milling the head's intake surface.

milled heads and valley pan

5wndwcpe

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Bighead440

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1 Wild R/T

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BSB67

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5wndwcpe

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RemCharger

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Don Frelier

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BSB67

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