[sdbob]

I'm going to look at 2 sets of 670 heads a guy has for sale. Can someone give me an idea how far a stock head valve is below the head surface? My basic question is to see how much of the seat has been used up. I'm thinking I'll use either depth mics or steel plate with dial calipers to get a rough idea,measuring from head surface to valve. Thanks.

[steve25]

I can let you know later this afternoon when I check mine.
My set has already had a valve job so it should be representative of the average rebuilt head.

[steve25]

Another way to tell is by the OD of the valve seat in the chamber.

In all the stock heads with 2.11” valves that I have ever taken apart the OD of the seat has been around 2.09” within a few thousands either way.

When a valve job is done if you want to make the best usage of the size of the valve you have then you want the new seat OD to be .010” to .005” the OD of the valve.

I use .010” for exh valves and .005” for intakes.

As you step up to the bigger seat OD the valve will sink that same amount.
So just going from the stock 2.090” to 2.105” will sink the valve .015”.

[steve25]

Bob I checked my most stock set of 670s.

These have had a freshen up valve job, been milled .006” and new original Pontiac replacement valves.

The measurement I got was .195”.

All you need is the Butt end of a dial caliper to make the measurement because the edge of the valve is close enough to the shallow side of the chamber to span the caliper over onto the deck.

The difference between milling the deck on my heads and the valve job makes the two come close to mulling out I think.

[sdbob]

Thank you. The guy is in our club.When we have next club meeting I'll get to his house.

[steve25]

Your welcome!