nickcornilsen

I've heard this is common and causes no issues. The heads passed a pressure test. I'm a little concerned about what looks like a second crack to the right of the obvious one. You can sort of see it.

What do you guys think?

jmilz28

iTrader: (13)

That could become an issue tomorrow, or not for years, or something else could go first. If it's running good with no leaks, just keep driving it as normal. Considering the (assumed) age of the engine, even if it goes tomorrow, it's been a good service life. JMHO

nickcornilsen

I should say this is an engine I'm assembling, and I have no history with the heads. (Swap meet stuff)

Che70velle

iTrader: (6)

Pressure test tells the tale. I’ve had this happen with a set of Brodix SBC heads. Tested fine so we carefully tamped the crack as closed as possible by using a fine point punch and light tapping from multiple places on each side of the crack. I ran nitrous through that engine without issue. You want try and make it disappear…even though it’s not…in order to remove any sharp edges that could lead to hot spots/detonation spots. Be patient and go slow. Hit it with a course cross-buff pad when your done to smooth it all back out.
You also want to pull the valves here and use a magnifying glass to make sure the crack is contained. If it’s made it’s way under the seat(s) and past them, you are likely to have issues. The seats will expand at a different rate, compared to the casting itself, because of thermal expansion variables between the two different alloys. As long as that crack is contained to that small area, your fine. I’ve also seen pictures like this from time to time on other forums, and the guys ran them as-is without issue. If your building an engine here that you expect to put 100k miles on, then you need to look for another set of heads regardless. I guess this all boils down to what your doing with the engine and your long-term expectations.

nickcornilsen

I've done some thinking, and knowing these cracks are there would feel like a sword of Damocles ready to drop any time. I'm going to find some new cores and replace the head.

Thanks!

Rich-L79

Why not just have the seats replaced?

nickcornilsen

The seats are fine, it's the head between the seats. For what a 799 core costs, repairing isn't worth while.

I took the heads apart today and one crack does extend into the exhaust port a bit.

Mr. Black

I kinda say this somewhat jokingly, but I treat looking at LS cylinders heads for cracks kinda like looking at LS cam bearings. Just don't. If you don't see it they're not a problem!