Blown out head

[jsnhutchinson]

Anyone ever see this happen? I was driving in my sand rail in 3rd gear wide open and all the sudden this blew out. Where can I get a new head at a reasonable price? I wanna get it running and sell it

[FreeBug]

Sorry to say, this probably is not going to have an easy solution, unless you know where the heads are from, and maybe it's some sort of "standard" type they sell, then maybe, just maybe...

But looking at the cracks formed and developing around the exhaust valve seat, you would do well to check the other head for cracks, and if it's cooked, it'll be an easy but more expensive solution: two new heads.

How many miles on this engine before this happened? There's probably a tuning issue, too, or C/R heat.

[jsnhutchinson]

What do you think would be fair asking price for this motor as is. It has dual weber 44s and new electronic ignition, and new flywheel, Kennedy puck clutch plate and stage 2 pressure plate. New rear main seal.

[raygreenwood]

As Freebug noted/pointed out......what you have us nowhere near a stock engine.

You have what appear to have begun life as a pair of 1.8L heads.....but have been flycut large enough that the cylinder diameter cut into the stud holes. Not saying that's bad or good.

So what else is in the engine, how many miles and who built it?

I ask because as Freebug noted....you don't just do one head.....especially if they are non stock. Someone is going to have to take either and old or new core, remove all ferrous metal.....replace the valve seats, flycut to size, possibly make alterations to chamber etc.

So.....as to what happened.....well....notice all of that greasy crud on the heads on the bottom side?
That comes from oil leaking out of the cylinders. This means that either the heads were loose, or not flat in their seating areas or had gaps from debris trapped during assembly etc.

Head seating area leaks......along with losing compression, running hot etc......cause the exact issue you have. Oil can keep getting in that gap between cylinder and head when the head is loose or not seated properly. Over time that oil gets cooked to carbon. As the engine runs that carbon can get so hot it glows. Eventually it forms a jet of flame that cuts tjrough the head like a torch.

And.....you dont know this yet....but that cylinder is most probably shot as well. It causes the formation of a heat stress riser. Yo u will usually find it when you go to lap the cylinder opening to the new head

If you are just wanting a decent head to slap on to sell it......try headflow masters or Roy at Mofoco.

There are others. Ray