I just sent the head to the mechine shop to be rebuilt and machined. He called me a couple of hours ago to tell me they have to weld the head to add some material so they can shave the head without it being out of spec. Will this cause any problems or is it perty much standard practice?

Hello.

I personaly think it would be more cost effective to start from a good core rather than adding some material. The welding process might warp the Head.

Most machinist will start by making sure the core is good for rebuild before they do any work on it.

An other posibility would be to use a thicker HG. Stock is 0.050" and if I remember right the Cometic are 0.057".

How far off is the Head???

Ghislain.

I don't know exactly but he said it's not that much.
I'll ask him tomorrow.

I'd be scared of any machine shop telling me "it's not that much" when referring to a measurement... Considering not that much could make the difference between perfect rebuild and total catostrophic failure.

If done correctly can it hold power?

I'd say yes but their is more to it than "just welding" material to a Head. The heat generated by the welding process could warp the head some more or cause other reliability problems.

Now just picture the Head as a block. On the other side of the mating surface you'll find the Cam Journals. The Journals will be misaligned the same as the mating surface. Cams will be subjected to the same "warpage" as the mating surface and their is the posibility they (Cams) will not line up perfectly and cause premature wear of the Journals.

The machinist I get my work done would not rework a Head that is out of specs. Yes you might be able to get them Aligned Honed but that procedure would co$t and would defenately offset the cost of starting from a good core.

1G Heads are a dime a dozen so starting from a good core would be a wizer choise if you ask me.

Now Nigel has nailled it; they should know by how much rather than saying "not that much"...

Hope this helps.

Ghislain.

Ive never heard of that method, ever. Where are they welding?? How much are they welding?? I would be very suspect.

The weld is very small about on inch long and half an inch wide. It's right beside exhaust valve, inside the combustion chamber.

Thats a pretty big hole for being in the cc. Are they putting in new seats?

Unless he's talking about welding the combustion chambers so that they can reshape them into a cloverleaf or something. I've seen honda heads that have had that done.

But why do it in the first place? It's not needed.

I'll try to get a picture of it. It's not noticeable at all. If he hadn't shown it to me I wouldn't have noticed it.

Much better.

My first understanding was they were going to weld over the entire maiting surface, that would of been a disaster.

Post a pic for all of us to enjoy.

Ghislain.

There is most than likely detonation damage in the cc. I usually just discard the head when that happens, 1G heads are not hard to come by.