Well my new A15 went 4 turns before it dropped 1 then 2 cylinders. The head gasket burned through between 1&2 and 3&4 and also left a lovely channel in the head at both spots, fortunately it's repairable. The motor ran sweatly.......till it didn't.
The cause appears to be head bolts either stretched or not properly torqued. When I did them up I was not crazy about how they felt. They all torqued to spec but there was just something odd. When we undid them the same kind of off thing.
Only other thing I could think off was that the Felpro head gasket wasn't up to the task of 12-1 compression but my bet is still on the head not truly torqued down.

On the plus side my buddy who preps spec miatas for people loaned me one of his cars for the rest of the day. Also my 1200 with the new suspension bits that went with the H190 and the spacers for the front struts have taken care off the couple of small things I wanted to improve.

Tom

Thats a bit of hard luck there Tom.

For head gaskets its hard to look past the factory "GX" 0.6 mm thick [good for up to 78.5mm bore from memory], or one of the nismo items. ARP head studs could be the go also, More a piece of mind part rather than essential. best of fortune with the rebuild.

I run the GX head gasket on my 78mm, 14.4:1 comp ratio 1525cc A series

cheers
benny

Benny thankfully I have the spare A12 to put back in. My A15 is at 1508cc and 12-1 with a 1 mm thick gasket. I'm going to upgrade the gasket and may well go with ARP studs. I also need to buy better pushrods as one of them was banana shaped, I have the chrome-moly ones for the A12 but not the A15..........oops

Tom

Was the head hardness tested?
when they go soft, the head bolt washers sink into the aluminium, and you lose clamping force. a good tell tale is if there are deep round imprints in the head where the washers rest.
I know what you mean about the head bolts not feeling nice as you did them up. It wasn't the washers sinking in was it?

Tom,
Did you use the Delta Cam that I sold you in this rebuild? Also, was one of the pushrods I sent with the cam go banana? Hard luck on the head gasket. Hope you put it back together soon.

tomei lightweight pushrods are the go. no more bananas.

No marks on the head where the washers seat so not likely gone soft.

I am indeed using the Delta cam, it seems to have good mid range but I need some minor jet corrections, I believe the main needs to go up one step.

If I can source push rods within the next week the the A15 could stay otherwise the A12 goes back in as there is a vintage race on October 6th.

Tom