A10 sump plate studs

[JOHNSTONE]

What is the thread size of the part of the stud that goes into the crank case and if required what size helicoil insert would I need .Thanks in anticipation.
Richard

[Jackson]

According to Draganfly they are 1/4, threaded CEI at one end and Whit at the other (presumably the crank case end)

[EDDIE SIMPSON]

the standard studs crack the sump alloy when tightened imo. i only use 1/4 whitworth studding. aprox 1 1/2" long. cut the head of some old timing case screws.
avoids sump welding repairs

[RESTORER]

The studs into the casing are definitely whitworth.  You will find that for all the threads tapped into ally, casing joint, rocker covers etc, BSA used whitworth.

[Marktomblin]

I have fitted several of these they are 1/4 whit I use stud lock lock tight and only tighten them gently the locktight does the rest to remove double nut and heat casing .