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Alan L Alan L is offline
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Join Date: Apr 2006
Location: New Zealand
Posts: 3,261
Thanks Jon - I don't think I have the C2T WUR. The only other diaphragm I have in there is the boost one.
When I say the diaphragm springs -adjust (allen key screw) sets the cold pressure - it equally sets the hot - in that it sets the baseline pressure on the diaphragm. Which in turn affects the hot and cold ultimate pressures. Yes, I have reverse engineered them too - crude stuff for such precise requirements.
So, with the bimetallic screw off the points, (low current draw) it warms up more slowly - but ultimately gets to same pressure setting hot?
Makes sense - whichever way I went, and for however long on heat cycle, I got the same hot pressure. It would seem to only have a 12 psi range - which by the book is about half what it should be - WUR specs - cold approx 20 psi (depending on ambient temp) hot 50 psi.
So, I'm missing half the warm up range. I guess I'll just have to bump the diaphragm spring pressure up.
I wondered about playing with the single bottom spring for boost dump rates too. But it was working as per the book at 7 psi drop, and I previously had it running very sweetly with stock internals. But If I keep getting excessive dump at boost, I will harden this spring up incrementally - 10%, 20% etc.
If you know where to go, it is quite cheap to get custom springs made up - few $'s.
That will be my final tweeking option before buying a digi WUR - which may well be happening sooner than later.
The odd thing is, my cruise AFRs go too lean - flat spot on throttle. While on boost, with the low CP, it dumps too much. So I am struggling between the two ends of the spectrum. If it was rich on cruise too, it would be simple - harden the CP.
But I will give this another crack - since I had it working pretty well a week ago.
What screwed me up was I was tweeking the bimetallic screw thinking I was fiddling hot pressures - the measured response first time was precisely where I was trying to head. So, I kept at it for more tweeking. I am suspecting the response I measured was some inconsistent fluke in the WUR and threw me right off track.
Old 07-03-2008, 01:02 PM
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