Thread: Help Me Pick Some Heads For Christmas Present

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I would check the rocker stud holes to see if any of them go through the roof of any intake runners. That could be a source of sucking oil into the motor. If they poke through, unscrew them and slather the threads with Aviation Permatex. I would completely disassemble the heads and give them a good washing. Nobody cares about your equipment like you do.

You want to make sure that the rails of the rockers will not contact the tops of the retainers throughout the full range of lift. If the retainers are unloaded by the rockers, the locks could drop out and the game is over.
http://image.superchevy.com/f/955873...mage_large.jpg
Roll the motor through 720 degrees to insure that you have clearance on all 16 rockers.

This photo shows the L31 head with aftermarket conical valve springs and reduced diameter retainers. See how far above the locks the valve stem tip is? I'm not sure, but the L31 valves may be a little longer from the stem tip to the lock groove than conventional SBC valves that use the conventional rocker tip placement on the valve stem (pushrod hole in the head or guideplates).
http://www.powerperformancenews.com/.../VORTEC-07.jpg

Here's another photo, showing a negative lock for decreased installed height (higher spring pressure) and pushing the valve stem tip further out of the lock, a standard position lock and a positive lock for increased installed height (lower spring pressure) and sucking the valve stem tip further down into the lock.
https://www.chevydiy.com/wp-content/...17/01/23-8.jpg

If there is insufficient clearance between the rocker and the retainer with the valves that Summit used, you could possibly change locks to add clearance. Using a negative offset lock will make the valve stem stick out more above the top of the lock and at the same time, will decrease the spring installed height, adding additional force between the head and the underside of the retainer. Before I did this, I would find out exactly whose springs are in the head and the exact part numbers, then contact the manufacturer of the springs and give them the new spring pressure. You do not want to exceed the specified on-seat and open pressure due to possibly fragging the cam. Find out exactly what cam part number is in the motor and call the manufacturer to find out the particulars, using the springs that are in the heads, but installed at a shorter height. In any case, I personally would not exceed 260 lbs open pressure, with about 80-85 lbs on the seat. If this were my motor, I would check the pressure at installed and open anyway, before I ran the motor. TRUST NOBODY.

The other thing you could do, if the rockers contact the retainers, is to change to valves with longer stem length above the lock. That would prevent changing the locks and the installed height of the valve springs. I would resist any tendency that I might have to grind on the rocker rails.

See page 340 here to see how negative (-) locks could raise the valve stem tip and also decrease installed height (increasing spring tension)
http://www.cranecams.com/uploads/cat...%20Catalog.pdf

Just a thought, if you had purchased Chevrolet 12558060 heads, none of this would be an issue.
https://www.summitracing.com/parts/nal-12558060

I wouldn't worry about any blemishes on the runner walls, the lion's share of flow goes right down the middle.

If I'm not mistaken, Glyptal is the same stuff we used to paint the insides of cylinder blocks with. I think it is a GE product that was developed for coating the wiring on armatures in electric motors.
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