Do you guys ever trust an aluminum head that's been overheated?

Some of you might have seen my Miata engine interchange question, but I thought I'd throw this out as its' own question:

If you know a head has been overheated and warped, but the cam tunnels are straight, would you use the head again after decking? This particular application is for a 99 naturally aspirated, mostly stock miata.

I've never really blown up any engines (luckily!), but some of my friends seem to have sealing issues when they've done it. Of course, all of these were high boost applications (4G63 & 420 DSMs, and a SR20 nissan).

All the time. I always drop it off at the head shop for an inspection first though for pressure checking and what not.

There are varying degrees of overheated- I guess it depends. They need a pop-up timer, like a turkey.

Have dipped before decking. I wouldn't magnaflux it if dipping shows any issues.

In reply to captdownshift:

Dipped?

In reply to RealMiniParker:

acid etch

I trust it more if it was connected to an aluminum block as well. Don't know if that's backed by science though.

I helped a guy who raced a car with the BP engine and they did overheat it in a Lemons race. They later gave me the engine to go over and try to fix/improve it and I took the head to a shop and found that not only was the head surface warped but the cam bearing were out of line as well. The whole head was twisted like you took ahold of each end and tried to make a "Twizzler" candy stick out of it.

In reply to captdownshift:

Doh! Wasn't thinking.

jimbbski wrote: I helped a guy who raced a car with the BP engine and they did overheat it in a Lemons race. They later gave me the engine to go over and try to fix/improve it and I took the head to a shop and found that not only was the head surface warped but the cam bearing were out of line as well. The whole head was twisted like you took ahold of each end and tried to make a "Twizzler" candy stick out of it.

That's my concern, but I have a pretty nice CMM at work here that I can align the cam journals to, so I should be able to see if they're in line +- .001" or so. I'm not sure what the factory spec is, but based on my experience, the align-bore of it should be within that.

So, the summary of it is, if the cam journals are straight, it's probably ok and worth a gasket set to try?

Depends on the head and how long it was running in a ruined condition. Ford 6.0 diesel and Chrysler 4.7 heads, throw away and try again.

WonkoTheSane wrote: Some of you might have seen my Miata engine interchange question, but I thought I'd throw this out as its' own question: If you know a head has been overheated and warped, but the cam tunnels are straight, would you use the head again after decking?

IF the cams turn freely, no problem.

Knurled wrote: IF the cams turn freely, no problem.

The cams seem to spin pretty evenly and freely, there's no binding or uneven spots, so I'm thinking game on, give it the old college try..