ok ended up with 16mm bolt which we drilled and tapped out to 7/16 unc to take normal head bolt.. made a few different sizes but 16mm looks best and most practical for job thanks for input
just to end...i did notice the metric difference..i did thread the internal of insert with same thread as normal head bolts..i loctited inserts in block 4off..Stripping was caused by torquing head bolts to book specs...motor is fine and was a complete success ..i dont own it now but i know new owner its still going strong so jobs a good one ..i reckon you can torque heads book style a couple of times after heads off but after that its a stripping threads possibility..i reverted to old fashioned torque down starting at 15ftlb slowly building up to torque which isnt in the book..i torqued to 60 ftlb...this was on 4.6l 2000 petrol with lpg the tightening by degrees is very scary i think ..it was this way or new block ..the helicoil method is doomed with all mine pulling out way before any real torque was applied ..any body else know an alternative ..maybe im just heavy handed
jon, a brief outline of the story. orginally designed by bmw the plans were taken as war reperations by you lot. developed and produced as the buick 215 which wasnt liked by you guys as the ally block didnt sit well in your cast iron minds
Where did this 'information' come from? the 215 owes nothing to any BMW engine (apart form being a 4 stroke!) It's very like every other American engine (material aside) an incredibly well production engineered engine. If it had been german it would have had handed heads and be hideously over complicated