Bolts instead of studs and small port heads

[DAVE BRADY]

Good afternoon,

Does anyone use bolts instead of studs?  I think I should be saying set screws rather than bolts but I am considering replacing the three long studs at the rear of the A65 crankcase with bolts.  The studs do not use all of the threaded hole and can be pig when assembling/disassembling the cases.  Any reason why not to do this?

I have been reading some very interesting stuff by Allan Gill on the Britbike Forum about heads, valves, torque etc. for A65s.
He refers to the small port head which is possibly and early one.  Does anyone know which heads and from what year?

Dave.

[LightningAndStarfire]

If the cases would need service a number of times the threads in the aluminium will be worn with bolts.

[DAVE BRADY]

Hi,

Yes, this is what I had gleaned from a bit of surfing and perhaps we have become obsessed with Allen screws on everything especially those bits that get fastened and unfastened during servicing like sump plates and rocker covers.
Although the threads in the location I am thinking about would only get disturbed for bottom end rebuilds I will probably get new studs.  Having examined the ones I have a bit more closely they are slightly bent thus a bit awkward parting and refitting the case halves.

Re the 'small port head', I have also found out that it is '64 - '66 heads that have this.  The theory (probably fact) I think is that the smaller bore increases the velocity of the mix in to the cylinder without affecting the flow resulting in better filling of the combustion chamber and therefore more efficiency.

Dave.