NTChrist

Hi,
I've bought a pair of 416's that I've disassembled in my living room (let me tell you, when I get out of college and move out, I'm owning a house WITH A GARAGE ).

I'm planning on polishing the runners, and I've read up a fair amount on that.
My questions are about getting it hot tanked and magnafluxed.

Should I hot tank the heads before I start polishing?

Should I magnaflux the heads before or after I polish them?

I've got new valvesprings to throw in (K-motion K-700's), and it looks like the old valvesprings had those "shims" underneath them, in the spring pocket.
Am I going to have to worry about getting shims of different thickness, with the new valvesprings? BTW, I am being careful that each shim is marked to its corresponding spring pocket.

My last question is a 2-parter. The previous owner said that he had screw in studs, and a 3-angle valve job done. Is there any way I can verify this by looking? I would imagine that there would be a nut in the middle of the stud, allowing it to be screwed/unscrewed in. There appears to be no nut. What's up?
Thanks in advance!

iroc22

You should get them hot tanked and mangnafluxed before you start ported and check for cracks.

You have shims in your 416's? I dont think mine have shims. I wouldn't worry about different thickness shims cause most springs install at the same height.

There should be a nut attatched to the stud allowing it to be unthreaded.

NTChrist

The shims that are currently in there are of varying height. I'll keep the corresponding shims with the pockets, as I replace the valvesprings.

DAMMIT!

That makes me wonder what else wasn't done.
Any way to tell if the heads were actually rebuilt? Are the shims a good sign?

five7kid

iTrader: (14)

Shims typically mean the valves/seats have been ground sometime since being delivered from the factory. Doing that puts the valve stem farther up in the head, meaning the spring will not exert as much force on it. When reassembling, each valve will need to be checked for installed height and shimed accordingly to get the spring at the correct starting point.

As Vader pointed out recently, there are screw-in replacement studs available that do not have the nut/shoulder on them. There is a slight "bulb" where it meets the casting, though. If you do a search, you should find the thread which includes a picture of each screw-in type (I think it was on the Tech forum, although it might have been Motor Swap).

F-BIRD'88

The "416" castings come from the factory with exhaust valve rotators instead of normal retainers. These rotators are thicker.
In order to have the same spring installed height with the same
standard GM valve length, GM machines the exhaust spring seats deeper than the normal intake spring seats. If you or someone
replaces the rotator style retainers with normal retainers,
you need to add spring shims to restore the spring installed height. The difference is about .100"
You want to set those K-700's up with 1.70" installed height.
You may need shims to do this. The stock valvespring oil shields are 1/32' thick (.03125)
You can do a pretty decent job of cleaning your heads at home
(but not in the living room)
with some oven cleaner and elbow grease and a garden hose.

Checking the heads for cracks might be a good idea before investing in any machining costs.

NTChrist

Thanks for responding guys, I've seen that you three know a lot about heads, and I was particularly looking for your opinions.

Five7kid: There are no bulbs, or nuts/shoulders. I think I got lied to. I'll email the seller, see what he's got to say.

Hmm, what F-BIRD'88 is saying, is that I may be looking at "Rotators" thinking they're shims....

Are rotators used on both the intake's and exhaust's spring pockets?

I was wrong about the varying thickness of the "shims" thing. Upon closer inspection, I've noticed that its the height of the pockets that vary. Just like F-BIRD'88 said. Sorry if that threw anybody off!
The rotators/shims have the identifier: V.S.I. 203 on all of them. If this means anything to anybody, let me know.

NTChrist

Oh yeah, and I'll check the installed height too.
1.70" from the bottom of the spring pocket?
Thanks!

Guest

Those are shims, not rotators. VSI is a company that makes the shims. Many times rebuilders throw them in there to add seated spring pressure, partly due to whats lost when cutting the seats and valves, but more so because stock springs suck. They're probably about .030 thick.

I'll bet the rocker arm studs havent been changed.

ede

spring cups will take up some room that the shims do and make for a neater job, and help center the spring. i'd not worry about the mag test and get the heads preasure tested

NTChrist

Thanks for the info, madmax. That certainly helps clear up what's been done to my heads.

ede: I will look into spring cups. One of the shims has had the stamped type worn off of it. I'll look for cups that are 0.03" thick, as madmax said.
Thanks for the help, guys!

F-BIRD'88

Rotators are a different type of retainer. They allow the
valve to rotate while the motor is running. This tends
to make the valve and valve seat last longer. They are generally only used on the exhaust valves.
They are not used for high performance use because they
weigh more. More weight in the valvetrain= lower resonance frequency (valvespring surge rpm).
An alternative to screw in studs is to pin the rocker studs.
U can do this your self with some small roll pins and a drill.
Just measure the diameter of the roll pins and select the
same size drill bit.

As part of your upgrade you may want to measure the distance between the bottom of the retainer and the top of the valve guide
with the seal installed.
This dimention varies alot depending on what seal and retainer you use.
You should have a minimum of .060"
more than your full valve lift to avoid damage at high rpm.