valve seats concerns T/A 340 Heads

[Rbob]

Looking for some guidance and suggestions, My heads have been cleaned up, machine shop says someone has installed valve seats and many are 25 - 60 thousands too deep which I can remember when that was done in the 80's.

Scary parts is recommended replacement with oversize seat inserts with risk of cutting into water jacket.

These are 340 T/A heads so I am stuck fixing what I have. Maybe taller seat inserts?

Photos tomorrow.

 

[Treblig]

Looking for some guidance and suggestions, My heads have been cleaned up, machine shop says someone has installed valve seats and many are 25 - 60 thousands too deep which I can remember when that was done in the 80's.

Scary parts is recommended replacement with oversize seat inserts with risk of cutting into water jacket.

These are 340 T/A heads so I am stuck fixing what I have. Maybe taller seat inserts?

Photos tomorrow.

If they are too deep by 30-60 thousands I don't see they couldn't be removed and a hardened spacer installed under the seat to raise it up??

 

[MOPAROFFICIAL]

Are we talking valve job is sunk .030-.060?

Or actual hard seats already installed and too deep?
Stem height variations of .030 sucks to work with but most of the time can be cut within a reasonable margin.
When you say "custom seats" im thinking a seat that's .010 bigger OD than a std replacement seat. Thats only .005 out each way.

 

[Rbob]

Are we talking valve job is sunk .030-.060?

Or actual hard seats already installed and too deep?
Stem height variations of .030 sucks to work with but most of the time can be cut within a reasonable margin.
When you say "custom seats" im thinking a seat that's .010 bigger OD than a std replacement seat. Thats only .005 out each way.

Correct, hard seats were installed too deep. I am not familiar with seat replacement but it seems I need a taller seat, just fear someone cutting into the water jacket..

 

[teringer]

that engine has adjustable rockers can't you work something out?

 

[PRH]

Really need pics before commenting

 

[PRH]

I have a set of T/A heads here that are in pretty sad shape.

Putting intake seats in stock 2.02 SBM can create problems..... especially if there is any core shift.

The heads I have here need all 16 seats, and there is “some” core shift.
They’re sunk, and badly corroded.
So, I contacted the owner and we had a little chat about the risks.
Basically...... they’re no good as they are, and they need seats.
So, I will machine them for seats and hope no holes appear.

 

[mbaird]

Don't they make taller seats ? That wouldn't fix the corrosion issue but in cases where the casting is good but seats need to come back to propper height it would .

Maybe time to go to 2.055s ?

 

[PRH]

I guess I must not qualified to properly evaluate the heads and come up with a workable solution to fix them.

 

[Rbob]

I guess I must not qualified to properly evaluate the heads and come up with a workable solution to fix them.

I guess I must not qualified to properly evaluate the heads and come up with a workable solution to fix them.

You are more than qualified,

I will send some pics when I get back from the machine shop, I did discover oversize seats (1/4" depth) that say to set at 7/32" and top cut to finish, in my case they may help.

Laughing at myself because you probably already know this.

 

[PRH]

What you have highlighted is why I mentioned there can be an issue with the intake seat install.

I had an x head here that had a couple of severely sunken intake seats.
Also, that head had some fairly prevalent core shift.
I got about 1/2 way into the 7/32” deep cut when a big hole opened up.
The head was no good without a seat........ so it was worth a try.

 

[Rbob]

Ok, got my heads back. Machine shop was kind enough to mark different heights, used a bridge and measured to a inserted valve for a zero point, in no certain order:
I need to look again but I believe only the exhaust seats were installed and not all were hardened seats.

 

[PRH]

Uuuumm..... yeh.

Doesn’t look like there are intake seats, but the intake are sunk pretty far.

The punch marks and hammered lip around the exhaust seats are a sign that maybe the installer wasn’t confident that there was sufficient press fit to keep them from falling out.
That’s some pretty ugly work.

See if you can get a reasonably close measurement of the exhaust seat OD.
The normal size for those heads is 1.687”, but I have seen people use 1.750”.

 

[PRH]

Check this one.
It’s fairly easy to see the OD of the seat ring itself.

If the 45 is anywhere near 1.600, then it looks like the seat ring would probably be 1.750”.

 

[PRH]

Here’s a set I fixed up a few years ago.
These had the 1.750” ex seats.
The big difference was neither were sunk too bad.
The ex seats weren’t pounded, and hadn’t moved at all...... and had been in there trouble free for years.
So, I left well enough alone.
I recut the intakes and the exhaust, and blended that lip out of the ex bowl.

 

[PRH]

How you like them to be......

 

[Rbob]

Looks like the smaller one:

 

[PRH]

Okay, that’s good.