Stuart triple timing

[Steamingandy]

Timeing a Stuart triple is often considered a black art, this is hopefully shows one of the the problems that I think gets overlooked,the drawings have a note on them stating “if the ports vary from the drawings adjust the length of the valve to suit”.
This engine shows exactly why this is important
To the drawings the port positions require the Valve to be 0.625” long
This engine has both inlet ports larger, lower 0.022” over size and the upper 0.060” over size total of 0.082”.
So the valve for this cylinder is 0.707” instead of 0.625”
The exhaust port is to size so valve is machined to drawings.
Hopefully this clear enough to understand with the pictures.

[Chipswitheverything]

Thanks for highlighting this matter to bear in mind. I will make a note of your post and keep it with the as yet untampered with Stuart castings... Might be a big help at some time in the future!    Dave

[Steamingandy]

Thanks for highlighting this matter to bear in mind. I will make a note of your post and keep it with the as yet untampered with Stuart castings... Might be a big help at some time in the future!    Dave

I have made a build log with pictures that could give you some ideas
<a href="https://www.youtube.com/watch?v=EIsR9KzR5Lk" target="_blank">http://www.youtube.com/watch?v=EIsR9KzR5Lk</a>

[Chipswitheverything]

Very pleased to see the record of your fine build in that way.  I see that, like Jo has done, you have built up the crankshaft, and I will do that as well, eventually! At Guildford, I was able to see the metalurgically failed examples of the Stuart supplied brazed up crankshafts that Jo had along with her engines.  In any case the machining of the crankshaft in one is a pretty fraught thing to try and tackle...   Dave

[Steamingandy]

I didn’t know Stuart ever did fabricated crankshafts for the triple,how had it failed? This engine has one machined from a casting, the engine has been machined very well by a member of my club over many years and due to age he can’t finish it, so I have offered to get it running for him.

Andy

[Steamingandy]

Progress from today, eccentrics set on crankshaft, refitted with flywheel and a bit of running in.

[Chipswitheverything]

Hi Andy, what Stuart had supplied for the crankshaft, at least in my 40+ years old set of castings from Henley, was a MS bar of oversize dia. with three MS blocks pinned and brazed along it at the placements and 120 degree angles needed.  Jo showed these failed examples of similar brazed blanks in her "Triple Orphans" build log a few years back:   and I happened to see the actual items when the show was on at Guildford.  Until then, I was scheming a way of using what Stuart Turner had supplied...  I have never seen a casting for a Stuart triple crankshaft, only for the twin cylinder launch engines.  Dave

[Steamingandy]

Dave
Thanks I have never seen one like that I will keep an eye out for them