Hi there,
Here be the big valves conversion made by Klaus Moning from Germany, Klaus is specialised in conversion from british cylinder heads, He changes my Fullauto head to plus 3mm valves on inlet and exhaust, I am very happy with is work.he samml If you wish to contact him, feel free to PM me
Yves
I'll post the next pictures in the next reply
Hello Yves and all who are intersted in this big valve conversion,
thank you Yves, that you like my work. I just want to point out that the big valve conversions can currently safely only be done on cylinder heads with the small outer valve guide diameter. These are the Fullauto and the 750cc cylinder heads. I can asure you that all work on Fullauto heads need to be done with the greatest respect for the pure quality (and expense) of these items.
I have yet to find a solution converting the heads with the bigger valve guides (850cc heads). If I re- angle those I end up with an outer diameter of approximately 18 or more mm. This is not acceptable, because towards the carburettor connection you end up having an 8mm long press- fit and towards the combustion chamber you'll have something like a 19mm press- fit. With this configuration you press the guide miss- alligned into the new bore. That's certainly not what you want.
Solutions could be:
1.) Welding the "old" valve guide bores in the head. This had been done several times but it seems impossible to weld the bores without ending up having blow holes in the welding.
2.) Weld in a bush for the new 750cc guides (laser- welding!!!). Rather expensive because you bore the new bores first, press in the bushes and than weld them up with laser- welding.
If you use 750cc cylinder heads you have the advantage that you can use standard 850cc guides after re- angling, which I did with Yve's cylinder head. Certainly with 750- heads you have to re- set the 4 outer bolt bores which are in a different position to the 850cc heads.
Anyway, Yves gave my E-Mail address further above. If you want the drawing and the (Excel-) calculations for the following valve sizes: 41/36, 42/38, 43/38 and 44/38 (mm) give me a message.
Best Regards
Klaus