Commando engine query(s)

Nothing wrong with push rods, they are in tolerance. The tolerance used back then could be measured with a rule. 

Hi Andy

I measured both my O.E. 850 exhaust pushrods which are the correct 7.30" or 185.42mm. Pushrod vertical, ball flat on the surface plate with a 12" straight edge next to it using the metric and decimal inch scales.

Metric measurement came out by eye at 185.5mm or a difference of 0.08mm/0.002" which shows how close you can get with a good steel rule and in my case +1.5 diopter glasses.

Your 187.5mm/ 7.382" pushrod is 1.5mm/0.59" too long so adjustment will be different and with a 1.13:1 rocker ratio an unknown geometry change.

I would replace both with new to match them up and maintain the rocker geometry assuming the head hasn't been skimmed. Yours are correct for a non Combat 750.

Ashley, you need to junk your old wooden ruler or zip down to Specsavers, no way is that tolerance acceptable.

My Mk3 workshop manual has the exhaust pushrods assembled length @ 7.321" to 7.285"

No need to replace any of them. If your bothered about it Andy, you can shorten the longest one by removing one end, filing the alloy rod end and refit the end cap.

As i have to tell clients, 'they weren't made very well'   

Don't need to junk anything or go to specsavers - I have access to the drawing and they are in tolerance. 7.3'' was not the correct length, it is just a useful approximation. 

Good call Ashley

Question, does the drawing show the length measured from spherical surface to spherical surface (ball surface to socket surface?) or/as well as the overall length?  

Great result with the engineering moment of clarity Andy. I've sent you a message re used Kibblewhite USA inlet valves.

Cheers

Neill