[Jackie55]

What strength metric bolt should I use for the cylinder head stud between the push rod galleries?
I'm fitting a new barrel/piston to a 1987 domestic market 350 and all was going well until I tried to reuse the cylinder head stud from the old barrel, and found it was a fraction too large for the new barrel. After some investigation, I found a garden variety zinc plated M8 bolt fits perfectly; so my plan is to get an M8 bolt with 60mm of thread and cut off the head- but is there a rule of thumb as to what grade bolt to use?

[Raymond]

I don't know if there is a rule of thumb and I don't know if there is a correct answer couched in specified shear strength of said bolt.

Differing grades of bolt will have differing stretch when tightened to correct torque, but I cannot think this will cause any problem as long as the bolt can be torqued up without snapping. And given the sometimes variable quality of Indian metallurgy, I think that is the only factor we need to consider.

So, I'd say, if it fits, go for it. Just my opinion, hope this helps.

[Adrian II]

If you were fanatical about it you could buy and thread up some 8mm steel rod in EN16 or whatever it's called now. I suspect a lesser grade would suffice if you don't go mad with a torque wrench.

A.

[stinkwheel]

Hitchcocks make their replacement cylinder studs out of EN8. So a grade 8,8 bolt would probably be a good donor.

Be warned, if it's an alloy barrel, the thread in the alloy strips easily, to the extent some owners (and manufacturers) cut out the middle man and fit an insert pre-emptively.

[bthtony55?]

Yip. En16 is fine. You could use EN8

[Jackie55]

Thanks all- I shall wend my way to the nearest village and procure a grade 8.8 bolt.