Negative Height Valve Spring Retainers

TT5.9mag said
Why can’t you use a thick spring locator? Howard’s had some 060 last time I looked. They may have thicker than that.

For example
COMP Cams 4713-16 COMP Cams Valve Spring Locators | Summit Racing

That’s .100 thick. The spring diameters may not work for you but they might have something that does.

The OD of the spring locator on the cast iron head is 0.994". The ID of the valve spring is 1.06". Not much room for the locator shim. If the head were machined for viton seals this would be easier.