Valve face depth in head.

RonA

RonA

Active member
Joined
Feb 26, 2008
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Because we are cutting things somewhat close I decided to measure from the head surface to the face of the valves. I told myself i wasn't going to get anal on stuff but i noticed that the measurements vary a bit. Enough for me to see it easily. Depth seems to vary from .015 to .050 it seems like it would have an effect on piston clearance. Would it be a good idea to take the head in to a shop and pay for them to get them a bit more uniform.
 
Wonder if that could be just a thickness varience of the valves them selves. I would pull the valves out and measure the deapth of the valve seats and then the thickness of the valves where they meet the valve seat.
 
I went through with a depth mic and marked them all. They range from .022 to .059 deep.
 
good god that seems like a lot of veriance. i could see .005, but .037, thats insane
 
Gentleman I know bought an engine that had a "big name" diesel shop do the headwork, same issue, it is now the way is should have been.
 
Did you have new seats pressed in? Also did u use all exhaust valves and seats for better flow?
 
Freezingsystems said:
Did you have new seats pressed in? Also did u use all exhaust valves and seats for better flow?
Click to expand...
Oversized seats, and oversized valves(1.38 dia.).
I just did the math and the average is .045 deep. Looks like all i should have to do is find a shop that can carefully re-cut and bring 8 of the valves a bit deeper in the head. If they can take them to .045 to .05 deep, They will all be within .01 of each other except 1 at .056 deep and 1 at .059 deep. I'll make some calls and see if i can find a good shop that can do it locally and save $600 in shipping.
 
RonA said:
Oversized seats, and oversized valves(1.38 dia.).
I just did the math and the average is .045 deep. Looks like all i should have to do is find a shop that can carefully re-cut and bring 8 of the valves a bit deeper in the head. If they can take them to .045 to .05 deep, They will all be within .01 of each other except 1 at .056 deep and 1 at .059 deep. I'll make some calls and see if i can find a good shop that can do it locally and save $600 in shipping.
Click to expand...


I would say shipping should be on the house...
 
Did you check your stem heights and spring installed heights? I would be more worried about those on a 4 valve head.
 
Spec intake Min .023 Max .043
Spec exhaust Min .038 Max .058

A lot of flow gains comes from the valve job.....I mean DAMN, this is on your new should be ready to go ported head?
 
Thank you for the PM Johnboy. Sounds like a few hours worth of indicating and lathe time along with a pot of coffee and a peanut butter and jelly sandwich is all it's going to take. Fortunately i need to change springs and retainers anyway.
 
gunracer1 said:
it just sucks that you have to do the rework.
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If i do the re-work it will be my call. It could have been done better, but the shipping back and forth is a killer. If all I have to do to make it fine is pull the valves and trim the end to get them level for the bridges, that's not a problem. If it's going to take alot more than that, I'll send it back and have it re-worked. I need a bit more info before i can make the call on it. I am going to check the installed heights of the springs and see if that varies the same amount(in theory, it should if the valves are all the same length). I would think that would cause a difference in seat pressure. This is why i try not to look too closely at stuff. When the measuring tools come out, I can usually find issues with anything automotive.:hehe:
 
Its amazing how some stuff will usually still work being off tolerance
 
Ron, I don't blame you for checking at all. The valves need to be set the same in the head. That is the starting point. Don't try to compensate by making adjustments other places. The intakes can be different then the exhaust, but both intakes should be the same, and both exhaust valves should be the same.

Seat pressure should be as close as possible so that both valves start to open close to the same time. Spring pressure when both valves are fully open should also be close, or one valve is going to be open more then the other (because of the bridge).

Stem height really mostly matters when setting push rod length. Getting them the same, means that you only need one lenght of push rod, to get the contact area in the bridge correct.

Just my $.02 worth...

Paul
Paul
 
paulb said:
Ron, I don't blame you for checking at all. The valves need to be set the same in the head. That is the starting point. Don't try to compensate by making adjustments other places. The intakes can be different then the exhaust, but both intakes should be the same, and both exhaust valves should be the same.

Seat pressure should be as close as possible so that both valves start to open close to the same time. Spring pressure when both valves are fully open should also be close, or one valve is going to be open more then the other (because of the bridge).

Stem height really mostly matters when setting push rod length. Getting them the same, means that you only need one lenght of push rod, to get the contact area in the bridge correct.

Just my $.02 worth...

Paul
Paul
Click to expand...


Stem height matters for sure when it comes to the rocker contact patch, but how does the length of the push rod change it?
 
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