Setting valve depth/height?

[Cuda416]

Something I've always wondered when considering valve jobs etc, is how to determine the proper depth of cut etc.

how do you decide, other than the width of the cut, how far into the seat to cut, make them all the same etc?

Not looking to do my own, just a point of curiosity..

Thanks in advance.

 

[brian6pac]

That's a ruff call, It depends on how bad the seat is and you only want to remove the amount needed to get it right, but you want the top of the stems the same or very close to each other.

 

[CRUZE 418]

That is about correct. I used to look in a book for stem heights, spring height etc.
I did overhaul head work at a couple of jobs that I had when I was in my 20's. Nothing fancy, just basics.

 

[Locomotion]

"Sinking" valves through excessive cutting and/or multiple valve jobs normally hurts flow. Otherwise, same as brian6pac said.

Best angles, widths, # of angles. etc. is normally determined by the flow characteristics of each type of head, the intended use, cam, rpm and experience of the machinist.

Trying to get everything the same AND best/correct is good for performance. "Blueprinting" - not necessarily to OEM factory specs.

 

[yellow rose]

You set the valve job on the edge of the valve and then get all the top cut in you can. And that’s how deep you set the valve.

 

[Cuda416]

You set the valve job on the edge of the valve and then get all the top cut in you can. And that’s how deep you set the valve.

Thanks, does this mean basically do what it takes to get the top of the valve to be as close to flush with the chamber?

 

[yellow rose]

Thanks, does this mean basically do what it takes to get the top of the valve to be as close to flush with the chamber?

I’m saying you want to get all the top cut in if you can. I like to see a .100 wide top cut IF it will fit. Sometimes you can’t get it all so you end up at .060-.070 wide.

I’ve seen really good head guys just get the seat on the head and then quit because they didn’t want to “sink” the valve. Getting a top cut isn’t sinking the valve, it’s finishing the valve job. Now, if you get all the top cut in you can and you keep dropping the seat you are going to lose flow.

 

[Cuda416]

I’m saying you want to get all the top cut in if you can. I like to see a .100 wide top cut IF it will fit. Sometimes you can’t get it all so you end up at .060-.070 wide.

I’ve seen really good head guys just get the seat on the head and then quit because they didn’t want to “sink” the valve. Getting a top cut isn’t sinking the valve, it’s finishing the valve job. Now, if you get all the top cut in you can and you keep dropping the seat you are going to lose flow.

Thanks, seems like I have some fun research to do.