Changed these for cheeseheads from allen sockets have fitted 6x1” long from 12 o’clock to 3 o’clock, remaining 6 are 1 1/4”, they all pull the case up tight. I haven’t committed a crime any where with longer bolts like blocking an oil drilling?
Attachment shows the pre-1969 Commando Screw positions. Most of the cheap replacement kits only contain two lengths.
I measured out all screws and arrived at 6 x1” and 6 x1 1/4”, these are very nice machined screws with slight filister head from RGM
At the risk of teaching you to suck eggs. Put the cover back in position and then use some form of depth gauge to confirm where the respective length screws should go. The drawing is not too helpful with a set of two-length screws.
On the subject of cover screw lengths, I once tried to replace the primary cover screws on an Electra which normally has 2 lengths with one extra long.. Couldn't get screws in so measured the hole depth in two other cases-2 versions. Spoke to Andy Soch. got a third length! so the actual hole depth between engines can vary! Turned out the first case had its holes bunged up with red Hermatite!
On the subject -although socket heads look nice they can easily be over tightened. So going back to Cheesheads made one a little more careful when tightening them to save scratching the case. Also one assumes that the original cheesheads were the correct length.
What i do is tighten each screw individually and watch it squeeze out the gasket grease found before just checking the depth doesn’t always check the full depth of the tapping
This may be useful to some:
It shows you where the different length bolts go, but also suggests a tightening order too, giving you the best chance of keeping leak free and not warping your timing cover.