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Discussion Starter · #1 ·
Looking for ideas from anyone on how this damage could have happened on this E88 head. This is the second head that this exact thing has happened to.over the last two race seasons. Material missing between cylinders 3 and 4 both times. Second head was machined and checked before installing. All new parts. New head gasket and head bolts.

My engine builder thinks it was caused by a predetenation in one of the cylinders due to both cylinders igniting at the same time. Thought it could be a spark plug wire issue or even within the distributor. Another suggested an over heating cause. Any thoughts?

108850
 

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A shot of the corresponding spot on the block might be helpful.

From the Guess Dept., I suspect that the block has a low spot/flaw/crack that would allow a tunnel effect for hot gases back and forth between cylinders to develop, burning away the softer alloy of the head..

$.02 from the cheap seats
 

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1977 280Z Manual
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A shot of the corresponding spot on the block might be helpful.

From the Guess Dept., I suspect that the block has a low spot/flaw/crack that would allow a tunnel effect for hot gases back and forth between cylinders to develop, burning away the softer alloy of the head..

$.02 from the cheap seats
I was wondering about this too. Has the block been decked? If not, has it at least been checked for flatness?
 

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Never seen damage like that. I would guess multi-factor cause. Lean af mix/pre-detonation/aggressive ignition timing & maybe cooling issues causing wide & rapid changes in cylinder head temp creating cracks.
 

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late 1970 Series 1 240Z
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The white spots are more then likely water boiling. If it were me, I would clean the block down to shinny metal and cjeck for low spots. A hi powered pencil beam of a flash will only tell you if the block is really warped. A feeler gauge will tell you more, HOWEVER, you need a machined flat bar to test this. I stress a machined flat bar. I would also heck your valve seats, loose? cracked? Detonation can cuse the issue also, but it would be really bad to do that much damage.
 

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I worked on a boat one time that the engine had been overhauled by a speed shop.
It had two 4 barrel carbs. The first time they ran it, wide open throttle, for a few miles, I could tell that old mechanical fuel pump was not keeping up. By the time we got back to the marina, the lean condition had burnt a quarter size hole in a new piston.
 

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If you look closely at the intake valve on the right about the 9 o'clock position it looks like the seat is exposed and the aluminum has been eaten away. Looking at the intake on the left at about 6 o'clock you'll see quite a lot of aluminum damage next to the seat as well. Do you have a really hot ignition coil like MSD? What about alcohol injection? Race gas? What kind of hp are you pushing, and is your engine turbo'd? These are all possible contributors to this condition. Pics of the pistons and deck would also be nice to see. On an unrelated observation, on most L engine heads between #3 and #4 cylinders there are 2 small coolant passageways for coolant. They are visible in your pic as well. Those look like they may have been eaten away a little. This is something to check on any head that has been pulled off. If the holes are chamfered along the edges they need to be ground down a little, then welded closed, and redrilled. There isn't much space between either of those holes and the edge of the metal ring for the cylinders. I've seen a lot of these holes damaged and a lot of times they start leaking coolant into one or both of the cylinders. One more thing to check into. Before putting a head on you need to chase the threads going into the block with a tap, blow out the holes with air, and you need to lube the threads on the bolts with a product like Anti-sieze. Is this being done. If the bolts hydraulic you won't achieve actual torque on the bolts and that can cause problems. Z Man of Washington
 

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Discussion Starter · #10 ·
Thanks for everyone's reply. Hope to get an answer back about the problem.
 
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