Potential risk of hardened seats

[mikec]

I had the dreaded oil leak at the head/water pump gasket and decided to pull the head and replace it. As usual, this led to a new project of evaluating the valve seats and their condition. I've seen some posts on adding the hardened seats but no comments on the risk. We have an experienced (old) machinist whom we use and he has said there is some risk in cutting into the water jacket when machining for the new seats. I think he was just going on memory here but he said if it happens, the head now becomes junk. Does anyone know if there is a "real" risk in having this process done? I think I am confused again. . .

One more question that is more intellectual curiosity - we were looking at the cylinders and we assumed the one nearest the fan is #1. One post I looked at said Germany sometimes used the cylinder nearest the flywheel as #!. In order to sleep again, is there an official picture/drawing that shows how they are numbered that I can see? All of my factory manuals don't show this. They do have a wealth of information on the bolt tightening sequence but don't show or say which cylinder is #1.

Thanks for your patience

[opelwasp]

As far as seats go unless you are going very exotic you'll be fine.

Cyl 1 is the front.

[tomking]

Nearest the fan is number 1. The european custom is for the one nearest the firewall to be called number 1.

[jeff denton]

But then when you go to time the ignition you'll find a little "gotcha" in that the cam is timed for #1 but at that moment the spark is timed to #4. Be sure to study up on this, it sounds confusing but it's really simple.
Hardened valve seats are installed on CIH heads quite commonly, do a search for it at this site and you'll see it.
If you'd like a little more performance, now is the time to gain a whole bunch. Look at the threads about bigger valves and porting.

[GTJIM]

Yep - have to be careful installing the valve seats - usually only done on the exhaust seat with Opel heads.
"Shallow" valve seats are used - around 7/32" (5.5mm) thick ... from top to bottom - if I remember correctly.
Best to have them installed by a shop that knows how to install seats in OPEL heads and is not finding out on your head what 'too deep' means .....
There is always a risk when doing non-standard jobs ... and the machine shop will expect you to carry that risk - not them. After-all, it is you wanting the non-standard job done and has to research the specs before telling the machine shop what you want done.

Be it on your head!

[2 Fast 4 U]

Nearest the fan is number 1. The european custom is for the one nearest the firewall to be called number 1.

No way josé, here is the #1 also nearest the fan, as wel in the European [Read German] FSM

[wrench459]

Whats the condition of the exhaust seats? More then likely pitted beyond belief. Now would be a great time to upgrade to hardened seats on the exhaust. As far as risks almost ZERO on a stock engine if you've got a good machinist. That said want for some more Opel power go to larger valves. Thats when things get hairy!!!!
Did you look at the cam Bgrs. closely?
Jim you kill me with the specs...inside joke.