Machinist Guys! Thoughts on installed valve stem height

[BillK]

First of all... I am pretty sure the AERA spec is what the factory production spec would be. The actual allowable production variance. I can call AERA tomorrow to verify but I bet that is the case. And yes they probably did vary that much back then. For a factory type stock rebuild that will work fine.

That being said ..... I like to try to get them all within .010 for most jobs. Closer if it is a non adjustable valve train and especially so on performance work. Most hydraulic lifters have quite a bit of travel room so the .040 variance is not a problem from that standpoint.

One thing that nobody has mentioned is the fact that the spring seats on factory heads can vary all over the place too. That affects your measurement of valve stem height. If you have a tool to measure the depth of the valve seat surface to the deck of the head you can try to get those all the same also..... which is more important ?

Also, how much did they face off the valves and off the end of the stems ? All of that affects the stem height. One thing you could try is take a single valve and use that one to measure all of the seats. That will tell you if the seats are off or the valves them selves or probably a combination of both Whether you have a gripe with the machine shop probably depends on what type of valve job you asked for.

[cgarb]

I can't count the number of times I've walked by cars at the drag strip and said "oh my, those valves are not the same height..." Oh, you can't see the valves with the valve covers on. So...it's within the .040" allowable spec and the problem is? The problem is it's not on the car and running. Is this a stock eliminator engine? If this is a daily driver/restoration type build it's fine. Put it together and use it for what it's for.

[Newold1]

Exactly, even though this an old engine platform the shop should familiarize itself with the engine type and refer back to a reference manual if needed and then should realize this is a no adjustment valve lash valvetrain and make sure when installing and machining new parts that it must hold valve tip heights uniform within the plus-minus specifications and with a dimension within the range dimension given. Could be the person doing the actual work was born long after this engine was originally brought into use in 1962.

[modok]

Why the heck wouldn't the heights be the same if a competent builder did the the job?

A fool does what he can
A smart man does what he wants
A wise man does only what is necessary

That's an old one but you could replace it with the learning curve and it would still work, novice, competence, and mastery

IN THIS CASE, I don't know whos right. Could be either way. Need to have a spec and then find out if it in our out.
but I've set up a LOT of engines with heights not all the same, for several reasons,so.... I don't know if I should take offense to that or consider it a complement

[BillK]

Exactly, even though this an old engine platform the shop should familiarize itself with the engine type and refer back to a reference manual if needed and then should realize this is a no adjustment valve lash valvetrain and make sure when installing and machining new parts that it must hold valve tip heights uniform within the plus-minus specifications and with a dimension within the range dimension given. Could be the person doing the actual work was born long after this engine was originally brought into use in 1962.

It sounds as though the heads WERE within the published tolerances. Maybe not as good as we would like them to be but within the factory specs.

[engineguyBill]

Why the heck wouldn't the heights be the same if a competent builder did the the job?

Certain valves and/or seats may need to have more material removed to get a good valve face and seat, as well as the fact that not all of the spring seats are at the same dimension from the factory, as Bill K has pointed out.
BUT a competent machinist would measure and grind the valve tips to insure that the installed height is the same for all installed valves . . . . .

[af2]

but I've set up a LOT of engines with heights not all the same, for several reasons,so.... I don't know if I should take offense to that or consider it a complement

The latter as a compliment!

[Newold1]

Correct! Thank you engineguyBill !

[Jeff]

Prosis list the early engine @ 1.930 to 1.970 and later @ 1.820 to 1.850, The machine shop should have checked stem height @ tear down and compared it to prosis if they are members. If not write it down for later. Stem height is important for none adjustable rockers, that is why there is a butt grinder on the valve grinder, on the average valve job most machine shops are going to butt grind the valves to set the height, this should have been done at any shop.

[EchoWars]

Agree with Jeff! But, while the book gives a spec for installed height, there's nothing given for acceptable variance.

Anyway, I have the heads back. As a followup, the shop told me that the spring seats in several locations were about 0.030" lower than the others and probably grenaded their measurements. Regardless, the end result was a range of stem heights that were going to be a problem with no adjustment to make up for the difference. Solution? New exhaust valves, and grind them so they match the intakes. They were apologetic, but I had to buy the new valves (so, not THAT apologetic). I just picked up the heads yesterday, and a cursory look indicates that they are likely OK...need to do more work but it's awfully damn cold out in the garage right now.

[Dave Koehler]

Good on them.

[modok]

Good result.