Don Terrill’s Speed-Talk

My machinist says my heads need shims under the valve springs. He said special locks that have the shim built into them are available.
(11/32” Ferrea radial groove/beadlock)
I’m trying to find them and having trouble. 1.250” springs.
I see most locks say +.050 but what does that mean. I need it to push the lock/retainer closet to the head to avoid using shims. Is the +.050 the lock I need?

+.050 will increase installed height..


You need -.050 to reduce installed height and increase seat pressure

why not use the hardened shims under the springs to prevent the springs from cutting into the heads ???

That’s also part of my question. Machinist said he didn’t like to use shims. They’ve been in a lot of other motors I’ve had with no issues.
I did have a buddy who’s motor had pieces of his shims all over in the pan. The shims broke along the little lines stamped in them. Not sure on what brand.

bobalattie wrote: ↑Wed Mar 07, 2018 9:44 pm +.050 will increase installed height..


You need -.050 to reduce installed height and increase seat pressure

Ok that’s the way I understood it but wanted to be sure. It wasn’t really stated where the .050 was being applied.

Also , when would the +.050 be used?

When you need a greater installed spring height to match the requirements, but there are no shims left to remove and you don't want to machine the spring seats to gain clearance.

crap website but these people have the locks you need - download the catalog for specific info

https://www.pppcenter.com/

I don't like using the + or - .050" locks. I would much rather use a different retainer. There are different retainers available to change installed height. As far as shims, there is no problem using them if they are used correctly. You should not put the shim under the spring itself. You should always use a locator or cup under the spring and if you need to shim, put the shims under the locator so the shims are not getting destroyed by the spring moving.

If you use shims, they should be hardened so that the spring ends do not chew out the shims. Don't know why your builder is worried about using shims, alum heads use them so that the springs do not chew up the soft alum.

As for 050 locks. I have used +050s a few times to increase installed height & I found the increase was only about 035, not the full 050. You may find the same thing with -050 locks. Try it & see deal...

There is no industry standard for +.050 locks or retainers. Everyone has their own idea.

I've had a couple of + .050's that broke. Then was told that can happen.

rdkonkel wrote: ↑Wed Mar 07, 2018 9:58 pm That’s also part of my question. Machinist said he didn’t like to use shims. They’ve been in a lot of other motors I’ve had with no issues.
I did have a buddy who’s motor had pieces of his shims all over in the pan. The shims broke along the little lines stamped in them. Not sure on what brand.

The shims with the "lines" in them are not hardened & not for performance applications. Hardened shims dont have the lines.

FastBuick wrote: ↑Thu Mar 08, 2018 12:57 am I don't like using the + or - .050" locks. I would much rather use a different retainer. There are different retainers available to change installed height. As far as shims, there is no problem using them if they are used correctly. You should not put the shim under the spring itself. You should always use a locator or cup under the spring and if you need to shim, put the shims under the locator so the shims are not getting destroyed by the spring moving.

Fwiw, my stock -781 BBC large oval heads came with .015" steel shims under the valve springs. I want to say 8 of them, but it's been years??

pdq67

rdkonkel wrote: ↑Wed Mar 07, 2018 9:36 pm My machinist says my heads need shims under the valve springs. He said special locks that have the shim built into them are available.
(11/32” Ferrea radial groove/beadlock)
I’m trying to find them and having trouble. 1.250” springs.
I see most locks say +.050 but what does that mean. I need it to push the lock/retainer closet to the head to avoid using shims. Is the +.050 the lock I need?

A shim under the springs to correct the installed height is common but be sure that only hardened shims are used.
Under no circumstances use only a .015 shim between the head and spring as they will chew up cause they are not thick enough.
Using a +/- .050 lock is fine if you only use a machined lock made from billet chromoly bar stock. They are the strongest lock available in either 7 degree or 10 degree.For strength i only use the 10 degree retainers and locks.
They are available for a 1.250 spring from comp. I use a couple sets a week on sm blk marine stuff.

The other option is to have your machinist machine the seats to suit the installed heights so a .060 shim will protect the head and avoid them chewing up a thin shim. Comp has an ID locator comp#4705-16 that will allow a simple machining of the guide post and spring seat to allow them to be installed and have all the same installed heights and protect the head at the same time.