"Light tight" valve jobs

[cjperformance]

Here you go ,,,

It is great to have a seat that is concentric to the guide and allows full valve contact (sealing) while not placing any side load on the stem/guide. Often what happens with a torqued down and hot cylinder head is different to what happens on the bench.
At least starting with a near perfect valve seat allows you to asses what may be going on in a running scenario after some run time and an inspection of the seats and valves. Not always practical unfortunately.

Sand and bearing grease

 excellent !

I used to do 46* seats with Neway seat cutters a long tine ago. It was extremely easy to feel if the seat was concentric as the valve would stick on the 46 seat far easier than a 45 seat. Once the seat is true yes they seal very well in quick time so I see why the factory did it. 46 also seemed a little more forgiving to a slightly off seat.
With older style slow ramp cams and soft springs they last fine when done right. That said I think a good 45 seat is better than a good 46 seat.
I dont have a problem with using fine lapping paste for a very light witness lap.

Prussian Blue is great if you are gentle on the valve. On a big valve you can easily get a 'good' blue impression if you clap the valve onto the seat with any sort of force. Use light finger pressure only.

1972ho wrote: ↑CJ just a question about a light clap of the valve to the seat for a impression,isn’t the valves working harder than that when the engine is running I mean when the valve closes with 150 to 450# of seat pressure seems you should be able to slap the valve down harder to see the impression.Just a thought?

To start with as good a VJ as possible you need to forget the springs. You can have a seat so far off that you dont need light to see tha gap and put a spring on it, the valve flexes oves and it will seal. Think of that with a solid roller spring pulling on that flexed valve when running and the impact on valve fatigue, the seat, the guide etc.
If you aim for a seat that is as concentric as possible and centeres in line with the guide centerline AND certainly no more off center than half of the valve guide clearance then you are off to a good start.
When i say light clap onto the seat, that light! As in 'just' enough to get a transfer of blue. You should be able to blue the valve, touch down on the seat , clean the valve, touch down again and get a reimpression of blue back from the seat. When the seat in not concentric, you can actually feel it without even using blue.

Keith Morganstein wrote: ↑Quoting an old post about Prussian blue

Keith Morganstein wrote:

Check seat to valve contact with Prussian blue paste. Clean the seat and valve. Apply a thin smear of Prussian blue paste to the valve face.

Position the valve in the guide and drop the valve into the seat. ( A tap with the finger will help it hit the seat) Do this once , with NO rotating of the valve. Pop the valve out pushing from the stem end and carefully remove the valve so as not to smear the paste. This will give you an accurate contact patch.

Important: DO NOT rotate the valve when checking contact!

^^^ yes as above.
On that point, if the valve is say out by .001" and the seat is out by .001" and you rotate the valve you would think the seat was perfect. Even if the seat or valve were concentric and the other was a little off the blue will be swiped across the seal face and can be misleading.

[cjperformance]

And how NOT to treat a valve !!

4000miles on a fresh engine from a "Chev Guru", new customer brings a car in for some work and "to adjust the noisey valves" , I ask for cam specs,, its a hydro cam, hmmm,,,

PhotoPictureResizer_180616_094541062-800x600.jpg

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And another!! Customer wonders why the cam took a dump??

20180616_094723-600x800.jpg

Valves in the Edelbrock heads still ran true! But were replaced. Pistons had floating pins so a cleanup and turn pistons on rods was easy, increased P.V clearance somewhat aswell

Valves in the 2.0L pinto head had .005" / .010" runout, also replaced. Pistons modified to avoid a recurrence!!

About 30% of my work is fixing stupid stuff like this.

[benno318]

wow
clearly there was no dummy assembling, p-to-v checking and what not, from the "guru" - he must know them well enough to not need to!!

i used to get quite a bit of "fixing" f-ups myself, but i must admit its becoming less and less since the opposition are slowly closing up shop one by one...

[zums]

Yeah. I have one. I just don't like wasting time I am not getting paid for. If I bounce the valve, give a quick look see, and see no light, I know concentricity is good, and WILL max my vaccum gauge. Then bump with a finish stone and the seat looks like chrome, I know it's as good as possible. No need to do 3 more steps I am not being paid for. No need to check with all that. I should clarify, it WILL max the gauge after the bump with a stone. Gaurenteed, without a doubt, 100% of the time. Why take 2 more steps. And yes, no springs, LIGHTLY setting the valve on the seat and not smacking it like I see a lot of guys do. And if it doesn't MAX your vaccum gauge out, not pull at least 20 inches, it's leaking, period

Far out,,, but if you have a leaker , is it the valve or the seat , your back to v blocks and gage , so which is a waste of time
Tom

Well, all you have to do, is look in the port, turn the valve a little, look again, turn a little, look again, if you see light when the valve is on one spot vs the other, its the valve. If you see light the whole time you turn in the same spot, its the seat. But, the light bump with the finish stone, told you if the seat was dead on or not. V blocks work too. When I grind valves. I have a magnetic base on my valve grinder, with an indicator. I place indicator on stem, check for straightness. I then grind valve. I then put indicator on seat, it will show the runout. Since you already verified the stem was straight, and or running true, I have a lacey Williams accu chuck in my Kwik Way valve grinder, sometimes the collet doesn't seat perfect, checking to verify it runs true, takes 2 seconds, the seat to stem is dead on if the indicator says it is. The only thing I am really not verifying, is the valve tip. I know from checking, and but grinding, an un countable number of valves, I know it squares it dead on. So, I am actually checking all that in a different way. It does save time.

Thats all well and good if you have short cuts that work for you without failures but if you are trying to gain a personal data base of what seat width and run out work with certain type builds without failure then there is no short cut
Tom

[Walter R. Malik]

wow
clearly there was no dummy assembling, p-to-v checking and what not, from the "guru" - he must know them well enough to not need to!!

i used to get quite a bit of "fixing" f-ups myself, but i must admit its becoming less and less since the opposition are slowly closing up shop one by one...

It is not really about 99% of the actual shops in business ... it is garage gurus and people assembling their own stuff. They simply don't know how to perform the required assembly correctly as long as they can tighten the bolts in the right place.

EVERYONE can be an engine builder; just ask them.

[gofaster]

CJ just a question about a light clap of the valve to the seat for a impression,isn’t the valves working harder than that when the engine is running I mean when the valve closes with 150 to 450# of seat pressure seems you should be able to slap the valve down harder to see the impression.Just a thought?

The spring pressure can bend the valve stem far enough to seat, but...

Did you ever bend a piece of metal back and forth to break it?

In a running engine if the valve isn't seating squarely, it is getting bent by the valve springs to conform to the seat.

In a very minor misalignment things may wear in after time and run okay, if you're lucky.

In many cases the valve stem bends enough times to break at the valve head.

Read every post I have made in this thread

Craig,

I was trying to respond to the question asked of you by " 1972ho" in the quote above.

I was not disagreeing with you, nor did I intend to step on your toes.

Your entries in this thread are spot on!

[cjperformance]

The spring pressure can bend the valve stem far enough to seat, but...

Did you ever bend a piece of metal back and forth to break it?

In a running engine if the valve isn't seating squarely, it is getting bent by the valve springs to conform to the seat.

In a very minor misalignment things may wear in after time and run okay, if you're lucky.

In many cases the valve stem bends enough times to break at the valve head.

Read every post I have made in this thread

Craig,

I was trying to respond to the question asked of you by " 1972ho" in the quote above.

I was not disagreeing with you, nor did I intend to step on your toes.

Your entries in this thread are spot on!

Ah my bad, , i should not jump to conclusions! Sometimes i find intentions get lost in text . I do apologise.

[cjperformance]

wow
clearly there was no dummy assembling, p-to-v checking and what not, from the "guru" - he must know them well enough to not need to!!

i used to get quite a bit of "fixing" f-ups myself, but i must admit its becoming less and less since the opposition are slowly closing up shop one by one...

It is not really about 99% of the actual shops in business ... it is garage gurus and people assembling their own stuff. They simply don't know how to perform the required assembly correctly as long as they can tighten the bolts in the right place.

EVERYONE can be an engine builder; just ask them.

^^ and then you get the customers that keep telling you what their mates think you should be doing/fitting

[Kevin Johnson]

Related thread: viewtopic.php?f=1&t=31260 "lapping valves to check seating"

[PRH]

A year old I know........ but I wonder on the SBC with the pistons in backwards........ were the pistons installed on the rods incorrectly....... or were they just in the wrong holes?

I’ve actually seen that a few times.

As for the OP’s Brodix heads........ Ive had them right ootb where the seat runout was pretty high.

[Kevin Johnson]

A year old I know........ but I wonder on the SBC with the pistons in backwards........ were the pistons installed on the rods incorrectly....... or were they just in the wrong holes?

I’ve actually seen that a few times.

As for the OP’s Brodix heads........ Ive had them right ootb where the seat runout was pretty high.

Installing pistons backwards was an old trick to gain a little power. I remember reading it in the Direct Connection Performance book.

1. Pistons
Factory pistons have the pin offset to reduce piston slap. By reversing the offset (reversing the
piston) engine friction can be reduced.

[PRH]

That’s less of a problem on something like a stock 383 or 440 where there aren’t any valve pockets.
But as you can see with that SBC........ it doesn’t work out so well when there’s a pair of valve pockets involved.
You have to turn it around, then put it on the other side of the motor to keep the valve pocket orientation correct.

As for the Mopars........ I just swapped the pistons and rods from side to side....... don’t have to press them on or off that way.
1 for 2, 3 for 4, etc.
This way you kept the rod chamfer to the outside, and had the F on the pistons facing the rear.

What I’ve seen a few times is like that SBC in the pic........ pistons in backwards, valve pocket orientation also 180* out.

[Kevin Johnson]

They aren't professional engine builders -- I think what they hear or read is V8 and reversing the pistons is more free power. They probably turn the engine over by hand and if it doesn't lock up -- good to go.

I have to caution people fitting scrapers that they cannot go by feel or sound. They must physically confirm that the proper clearances are present.

[cjperformance]

A year old I know........ but I wonder on the SBC with the pistons in backwards........ were the pistons installed on the rods incorrectly....... or were they just in the wrong holes?

I’ve actually seen that a few times.

As for the OP’s Brodix heads........ Ive had them right ootb where the seat runout was pretty high.

Re the SBC with pistons backward. That was a 383 stroker and had H beams so no factory markings. Seeing it had floating pins I simply turned each piston around on its respective rod. It required new bearings aswell, the builder had used a new GM block and obviously didnt know about the plug required to be fitted into the oil gallery to direct oil thru the filter!!