1966 401 NAILHEAD VALVES SPRINGS HEIGHT

Hi, i'm back here with a new name, I had to change my name which was bertrandboss, my mailbox having been hacked !
I still own my 1966 Buick riviera GS, the engine of which was changed by one of the previous owners, for a 401 nailhead (MR code).
The cylinder heads are being completely refurbished, and I need information about the height of the valve springs.

I know that the height is measured with a special micrometer to determine the height of the springs, as well as the thickness of the shims intended to adjust this height.


I need several informations : 1 ° Is there an average height of the springs which must be respected, or are there other parameters to take into account to adjust the height ?

2 ° What is the procedure for measuring the height with a micrometer, and to determine the thickness of the shims, (how to use the micometer) ?

3 ° Where can I buy single shims , (I only found them sold in lots)


4 ° I looked for a micrometer on the web, I saw that there are different models compared to the measurements they allow to perform : 1.600-2.200 Height range or .600-.950 height range, etc.
What model / what heigght range do i need ?


Thank you for your help.

Bertrand
 
From the 66 Chassis Service Manual listed in the reference section of our site: 1.690" closed inner spring height and 1.600" closed outer spring height. Also important from thet manual: the normal height of the valve stem above the valve rocker arm cover gasket surface is 1.540". You should be able to put a straight edge across these and have little to no clearance under the straight edge. Machine shops often mill them across that plane when the other processes are completed and they are all close.

I used my vernier calipers last time checking my spring heights. I subtracted the height of the retainer for both and added the depth of the pocket for the inners. I used my vice and the same calipers to determine coil bind. You may require different installed spring heights and spring pressures if installing an aftermarket cam. Some may require machining the spring pockets.

Check with you local machine shop for shims or a lead on shims. You may want to measure everything out before looking for shims. That way you will know how many of what you will need if any. Most times a common shim is used since common machining is done to the head.
 
You might get some from Carmen Faso. He is the guy I have used to rebuild my
"best" heads and he pays attention to the spring height. 716-693-4090
 
^ +1. I have two sets of Carmens heads that i can't say enough about (one was formerly a set of yours Ted). When I changed cams he spent a lot of time with me over the correct springs, shims, heights and binds I would need.
 

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