Engine: Valve dimension ?

[kmac530]

So with everyones help, thanx, I have figured out basical what I need to get my heads back together.
I asked on another thread, but it was kinda dead by the time I asked so I will throw it out again.

Does anyone have a dimension for valve stem height from ANY point on the head?

It can be from valve spring pocket base to valve tip, it can be from deck height, head bolt seat, to valve tip, about anything where I can get a min-max number to see how much my machinist needs to cut off of my new exhaust seats, and then where to set my soon to be new intake seats so that my valve stem tips end up at the right point for rocker arm geometry and spring pocket depth.

Any help will be appreciated.
Even if someone has a brand new/NOS head sitting around and can throw a caliper from the machined head bolt surface to the top of the valves, that will at least give a good ball park to start with.

[Alan]

Should be 2.031" from the spring seat to the bottom of the retainer.

[kmac530]

Thank you Alan.

[kmac530]

So I measured my valves and my Intakes are are about 2.049" so that is 0.018" more than the 2.031" spec that Alan posted. Is that still an acceptable spec for a head that has the valves reground? Or is that too much?
It seems like that is well within the geometry for Stude valve trains, but I am not knowledgable enough to make that call, It just sounds like that is within an adjustment capability?

So I gues my question is, if 2.031" is the measurement, is there a min/max dimension? If not how do they allow for reground valves?
I get that you can shim the springs to get to that dimension spring wise, but that would not affect geometry, right?
Min/Max?

[PackardV8]

Yes, you can shim the springs to 2.031" installed height. However that dimension is nominal. What you want is at least 105-115# @ 1.671".

Yes, .018" is within the adjustment range.

Just for the heckofvit, are you sure the intake and exhaust valves are the same length? You said there is .090" difference, of which only .018" is intake grinding. It would be unusual for the exhaust seats to be .072" high. Over the years, I've seen rebuilders throw in all kinds of shorter valves to save a buck. For years, one supposedly good Stude guy used Ford Y-block valves, which are shorter.

jack vines

[kmac530]

The valves are still the originals I sent him, or at least the originals that were in the motor as I got it.
They say RMC and have a logo that looks like a Stude logo with an S in the center, then the intakes are marked INL with and 81 or 18 sideways and the exhaust EXH with a 55.
The intakes {the 2 I have off and can measure} are 5.200 long and the exhaust measure 5.180+or-. So about .020" shorter.
The new exhaust seats sit way down into the combustion chamber {way up towards your eyes if you are looking at the head upside down on a bench}.
The exhaust measures {not an exact science since I am using a caliper depth gauge on the end} about 0.060 raised from the chamber and the intake about .060" recessed into the chamber.
I hope this makes sense?

Thank you guys for helping me.
Kelly

[kmac530]

Could it be possible that the 0.020" longer Intakes could be from the int valve head cupping?

[Ron Dame]

For those of us who aren't as well informed, please enlighten us with how .020" affects vale train geometry. I understand how the lash is crucial, but what geometry is affected, and what is the result of it being wrong?

So I measured my valves and my Intakes are are about 2.049" so that is 0.018" more than the 2.031" spec that Alan posted. Is that still an acceptable spec for a head that has the valves reground? Or is that too much?
It seems like that is well within the geometry for Stude valve trains, but I am not knowledgable enough to make that call, It just sounds like that is within an adjustment capability?

So I gues my question is, if 2.031" is the measurement, is there a min/max dimension? If not how do they allow for reground valves?
I get that you can shim the springs to get to that dimension spring wise, but that would not affect geometry, right?
Min/Max?

[Mike Van Veghten]

1. these small valves shouldn't be "cupping" at the low factory spring pressure.

2. the shop you used SHOULD have evened out the stem height for you. This IS part of the procedure of doing a quality valve grind.

3. I'd say no more than an .008" difference from valve tip to valve tip...all the way across. This is for a cheap rebuild. Have the shop fixt this problem before you reinstall the heads.

4. the springs can be shimmed as required to obtain the correct/usable spring pressure with the correct thickness spring shims that the shop sould have provided to you. There is a very real possibility that each valve may take a slightly different shim to bring the spring into it's correct load (pounds).

5. The valve grind SHOULD have been done with enough care that the seats are within at least .010" in height. The stem can be ground to make up the difference to even out the tip height.

Mike

[Mike Van Veghten]

Ron (et-al) -
I'll explain a VERY simple rocker to valve tip relationship.

1. Draw a circle.

2. Put a small diameter stick, pen cartridge...something small but long enough to stick out of your circle. This is your rocker arm.

3. Stick a pin in the center to locate the stick.

4. Put the stick at a 90 degree position. Draw a line on the circle at this point. This can be considered your rocker to valve tip point.

5. Push the stick down, 1/2", following the actual raduis or curve of the circle...and draw another line on the circle at that point. (NOTE, the 1/2" will be less thAn 1/2" if done on a straight line...right?).

6. Put the stick back up at the 90 degree point.

7. Now...draw a "new" (out of spec.) line on the circle...say...1/4" (on the radius) down...from the original point.

8. Now put the stick on the new (out of spec.) line...and move the stick (rocker arm), down the original 1/2" (on the radius of the circle, NOT a straight line..!!).

If you've done this show and tell correctly, you'll see that as the incorrect movement of the rocker goes "around the corner" of the circle toward the 6 o'clock position, you'll see that by the time the rocker tip gets to it's 1/2" movement (lift) point, the valve tip moves at a lesser and lesser degree as it's moved toward the 6 o'clock point.
Heading to the 6 o'clock point is as you can imagin...an exageration...it shows what can happen to lessen the valve lift, the duration...AND the extra side load that the rocker now puts on the valve tip because the rocler tip is moving more sideways thAN it is/was, up and down.

Sorry, in kind of a hurry, hope you understand the explanation.

Mike

[kmac530]

Wow, Mike that was awesome, big demo with graphics and visuals. Nice.
Ron, just to re-state his description, If your rocker arm is level with the head and pivots on its axis {rocker shaft} if the rocker shaft rotates more than a few degrees, the tip is getting closer and closer the verticle line of the rocker shaft axis. Since the valves move veritically up and down, and the push rods move {basically} vertically, they move differently than the circular rotating motion of the rocker arm.
To exaggerate, if the rocker rotated 90*, the valve tip and pushrod tip would be straight up and down.
So if the seats are TOO high OR too low in the head, it pushes the valve tip up or down rotating the tip of the rocker higher or lower. Technically if you had a high enough lift of a cam you could rotate the rocker until it popped off of the spring and inside, not actually viable, but potentially possible.

Mike, thanks for the help. My Intakes are well inside of spec and he only changed the exhaust seats so he screwed that up bad. He is gone for a couple of days, so I will let all of you guys know what he says as soon as he gets back to me.

[Ron Dame]

Wow, excellent Mike. I've always wondered, but not really understood. With the gross movements of 1/2" in your illustration, it's obvious. I guess I am surprised that as little as 0.020" would change things that much, but I've not stayed at a Holiday Inn Express recently either.

[kmac530]

0.020" would not worry me as much. My exhaust and intake valve tips are about 0.090" diffference which is very dramatic. It is so bad that my 0.430 lift is causing the valve retainer to hit and crush the valve stem seals. Deffinately enough to not only cause a bind issue, but also geometry issues.

[Charlie D]

Kelly,

I have very little experience in this area but I might offer a guesstimate as to the situation. I started a thread about 4/7/11 concerning hardened exhaust valve seats. A quick summary is when my machinist milled the heads down to install the normal 7/32 hardened valve seats about 30-35% of the casting under the middle two exhaust valves had been milled away. He called me down to his shop and we discussed the alternatives of maybe using the 3/16 hardened valve seat on the other set of heads. I made the decision to go with what we had. I asked about this at last year’s co-operator meeting at Springfield and Mr. Myers thought that the hardened valves may come loose without more meat under them and said he uses a thinner hardened valve seat.

Could it be that when your machinist started seeing the casting being eaten away that he stopped milling and installed 7/32 valve seats in a milled hole that was not as deep. This would force the valve seat to be above the chamber of the piston. I think in your last post you mentioned something about this. It could be that he can mill the holes on down to 3/16 and put the thinner hardened seats in them. That should get the seat on down in the chamber and bring the valve stems up an undetermined distance. With Jack and Mike helping you, you are getting some good advice. They have been very kind to me and generous with their advice for my project.

Charlie D.

[kmac530]

Thanks Charlie,
Both Mike and Jack have been instrumental in getting me up to where I am with my engine and truck in general, MAJOR thanks to them both.

I dropped the heads off at my machinist, I feel I need to give him the chance to make it right. I showed him what the issue was, he could see it right away. He is going to fly cut the face of the seats to shorten them, then re-cut the angles on it to seat the valve back where it should be. He will set the retainers as close to the 2.031" space as possible, then trim the tips to get them within 0.004" of each other to re-align rocker geometry.
Then he will install my new HiPo springs and shim the for even pressure.
As soon as my springs show up, he should be able to do it in a day or 2. Here goes nothing.