So I have taken the tappet cover off this afternoon to adjust the tappets as they are quite noisy atm, they seemed to be louder after I had rebuilt my carb and fitted that all back up but that's another problem, man those carbs can get on my nerves sometimes.

What the problem is though is that when I was adjusting my tappets I noticed the middle three rocker shaft retaining bolts are loose! I pull them out and they all took a nice spirally chuck of head with them also a couple of pushrods may be slighty bent.

Has this ever happened to anyone before from overrevving\ overheating\running backwards\ tight valves? Somehow I think using helicoils to fix the threads is a bit risky but they love alloy. The more logical fix I think would be checking one of my bare heads in the shed and getting the gear transferred over to it.

Got to hand it to that motor though, it's a champ for putting up with me for as long as it did and all the owners before it.

sounds like the head is definately cactus

maybe bent valves as well

i think it may pay off to get new valves and put on another head, and check the pistons for dents when the head is off

fairly common for the pedestal bolt threads to give up, any abuse, over tighten heavy springs etc,
helicoils a common fix, Time-Serts the best fix...

As long as the head itself is serviceable, then repair it with a suitable thread insert.

If done properly, the repair is actually stronger than the original alloy thread. No point in writing off a perfectly good head over such a little thing as damaged threads.

true, i was thinking if he had a spare (entire head/valve/rocker assembely) it would be a lot easier and safer to just switch over

or even better if it's an a12 we are talking about get an entire a15 for it

I've got an entire A15 I'm building, I'm just lazy and haven't called Jeff back to give him some specs, he was going to hook me up with some gear for it like cam, flywheel, ect. Got an A14 that needs an inspection as it was spewing smoke after a khanacross. I also have an assembed A12 head but it may have chips out of the combustion chambers as some air filter bolts found their way in there when I first got a weber.

This A12 is only spose to be a in between motor for me but it does have to get me home, when it's out then I'll give it some love like a nice new set of pitsons and a portjob or something cos it's a special one, it's from my coupe

your head is soft
you dont bend valves by increasing tappet clearance
timeserts better than recoils but head is on its last legs
plan for another head in the near future
dazza

you know I did a search before I started this topic and Dazza said just about the same thing about the head to another bloke. It's just one of those things that are true though

30 year old head
its a pretty good bet

seen ea ford heads w/ 28 recoils in the top.....
then they blow a head gasket
sigmas used to deform the head bolt bosses at 50ft lbs, you could watch the boss squeeze out from under the bolt like cheese while trying to torque down