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9 1/2 Engine rebuild II

Posted: 14 Apr 2018 15:42
by VesaII
Heads are done and ready for coating. Peter at company Virtauskansi did really a first class job. He thinks we might get some 10-15% more flow by this. He also found some nasty brittles on intake seats. Luckily they are horisontally thus not altering tightness.

And three pictures...
Notice how smooth radius cut valve seats are and notice 30deg cut back on intake valve. Valve guides look like they should now.

http://www.hotrod.com/articles/valve-angle/
http://www.williamsperformanceengines.com/valves.html
http://www.rlengines.com/Web_Pages/Seri ... chine.html

Re: 9 1/2 Engine rebuild II

Posted: 01 May 2018 12:31
by VesaII
Exhaust valves...

As you may recall i was forced to replace one exhaust valve. When i saw how much nicer new exhaust valves was, i could not resist to change them all. Here you have some pictures and arguments why this was a must. Initial plan was to use old exhaust so they are rebuilt as well, but they has only one 45 cut on them.

1) New exhaust valves weight 47g when finished. Old ones some 51g and intake as comparison 52g as average.
2) New valves have thinner shaft
3) Second 30deg cut is done immediately after seating surface
4) There is more material on new valve head to make it more reliable when seating surface is moved out. It also allows a nice radius on side of combustion chamber: http://www.s262612653.websitehome.co.uk ... heads9.gif

After this mod there is not much improvement left to do on cylinder heads but coating...

Re: 9 1/2 Engine rebuild II

Posted: 06 Jun 2018 19:16
by VesaII
Will be continued in here http://www.ital-web.de/forum/viewforum.php?f=25 with more pictures...