sump wrote: ↑22 Oct 2020, 10:55 Well Thanks for all the replies.
The studs on that head had been replaced with bolts and the bottom bolt just fell out while in Henley at the trad rally. I picked up a new bolt from an exhaust centre and duly bolted it in but by the time we got home it was missing again!
On further inspection I removed the top bolt and found that although a little loose in places the treads wer'nt actually stripped out just worn?
Fitted a new gasket and new bolts and managed to get it to hold. Bolts are still there to this day but it blows so obviously I just can't get enough purchase to nip it up enough.
Wondering now after all the replies if it could be possible to just re= tap the thread that is there?
Perhaps you are trying to over work the bolts and head threads?
With an early system without the support bars ( lost on mostly all vans now) this often happens.
Try releasing pipe clamps and loosening. Otherwise bolts are fighting the clamps and not seating naturally. Tighten manifold bolts. Then retighten clamps