Hi, guys. Looking for suggestions on how to best approach shimming my valve springs.

The engine is a Ford 300 inline six. I have oversized valves in it but the only manufacturer of oversized valves for the 300 discontinued them. I was able to buy intake valves from them but not exhaust valves. I'm using SBC exhaust valves which are 0.101" longer than the intake valves that are sized specifically for the 300. This is why I'm needing advice. I've never done this before.

The springs and retainer kit is a Crower 84010, made for the 300, meaning the springs are Crower 68305 and the retainers are Crower 87048. So basically the intake side of the valvetrain can be left alone.

I need to find a way to make up this 0.101" difference in valve length with the spring. I could simply shim it, but the spring boss on the head is only about .020" more than the 0.101" difference and I don't feel that .020" is enough to reliably locate a valve spring.

I've heard of people using shims, locator cups, and I think I remember someone online mentioning that you can get retainers that add height to the spring?

How would you guys go about doing this? Never messed with springs before. I'll take all the advice I can get.

 

Did you try TI valves ? If they don't have them then no one does. .101 is way too much to shim for the springs and the extra valve length is going to mess up your valve train geometry also.