I took my A series head into a machine shop this morning. It was a bit compressed under the head bolt washer between the exhaust ports on 2nd and 3rd pots. He then got a little bouncy ball in a tube( ACL Hardness tester) and checked the head all over and it has apparently gone soft . Has this happened to anyone before with an A12 . It seems very feesable. He said not to use it at all?? Has anyone used a soft head? Just would like a 2nd opinion as some machinists can get a bit OTT.

get it re-tempered. Not that expensive....

What does re-tempering invole?? Do machine shops generally do this??

its an a12 head... cheap and easy to get.....just get another one.....

took 3 attempts for me to get one that wasnt soft when i was looking to get one rebuilt

why root around with one thats stuffed?

Ive got a good complete a12 head for sale ,PM me if your interested :)

not worth it, put the h 89 on it or another a12 head, to temper a head,first it needs straightening,then all metal needs to be removed(studs/guides/valve inserts/welsh plug),after heat treating is done, all metals need to be re fitted/machined, then p/test & head service.(expensive cost for a a12 head).

Why do you say "not worth it"? What has actually happened when using a slightly soft head?

Gasket manufacturers says don't use the head if it is under 65 Brinell hardness. But new they may only have 80 hardness...

good s/hand a12 heads here are worth $50-$150,why would you go to all that trouble/cost to re do a soft one.

By the way, heads don't go soft from age, or from engine overheating. They get soft when a machinist tries to straighten a warped head and heats it in an oven. Softening begins at around 290-310° C. Machinist should never heat a head this hot, but sometimes they do and it softens the head.

Agreed, spending all that money on rebuilding. But the question is "Has anyone used a soft head?"