Valve springs shims

[Manu Mach1]

Were shims under valve springs installed originally on our 351 4V's or it's something we can add to increase spring pressure?

 

[basstrix]

I don't know for sure that any heads came from the ford factory with shims, but if I had to guess, I'd say yes. Some of ford's heads came equipped with hardened spring seats...one could argue that these are a form of spring shim. If you leave them out, the installed height will likely be wrong. Due to the softness of the metal, aluminum heads should always use a hardened shim or spring seat to prevent the spring from eating into the head.

Shims can be used to set the proper Installed Height of the valve springs. They should not be used to compensate for a weak set of springs. A spring that doesn't meet minimum specified force at specified installed height should be replaced.

Installed height is designed into a given cylinder head configuration and, for an OEM build, is a fixed distance. In general, installed height increases as valves and valve seats are re-surfaced. Shims are used to return an overly long installed height back into spec. Offset valve stem locks and retainers are also available but require additional considerations.

 

[Don C]

+1. Also, if you start trying to shim up springs to compensate for weaknesses you can get into spring binding issues.

 

[Paul of MO]

No shims on an OEM 351C - Ford does not even have a part# for such an animal.

If your springs are weak then shims will not help for long.

If you are using aftermarket springs then shims can be used to even everything up as far as height and spring pressure.

No need for high spring pressure on a street driven car. If you are never going to wind it up to 6,000 rpm or higher then simple low cost replacement springs are just fine.

Be sure your have the correct retainers (the flat disk that sets on top of the springs) as late 351C and all 351M/400's have a "thick" retainer designed to promote rotation.

These are thick enough to cause coil bind even on some OEM replacement springs. I have seen these show up in more than one 351C rebuilt by someone who does not speak Cleveland.

Check out the front retainer compared to the next one back.

Just buy a matched cam/spring/lifter set and you will be good to go.

- Paul of MO

 

[secluff]

Paul is correct as Ford did not use valve spring shims from the factory. The Boss 302, 351, and 429 CJ, SCJ used a spring seat. I had pulled the aluminum valve covers off the 429 CJ in my Torino to clean and shine them up when I noticed a plate under the springs. Shop tech told me because of the stout springs used on those engines, the seat was actually a barrier between the spring and the head and also kept the spring in place preventing any spring movement.

The 351C 4bl (M & Q) actually used a 428 CJ/SCJ valve spring. Those are pretty good springs. So if they are original and weak, now would be a good time replace them. And like Don C said when you start shimming your springs you could likely end up with some spring bind

 

[Manu Mach1]

Thank you I got my answer, I don't want to install shims, just want to know it was factory installed. Thank you.