Good & Tight wrote:
Couple questions here, Otis:
1. Any reason you have left the mounting flange as a single continuous piece for all 6 cylinders?
I understand the concern about having the setup being more or less rigid, but differential heating along the length of the head and between the 6 tubes can lead to a lot of distortion--especially so where the flange is 3/8" more or less and the tubing proper around .060". ISTR reading someplace about it being a Good Idea to have the flanges for each cylinder separated. Not by much, maybe .100", but enough to allow for possible different amounts of expansion when heated to exhaust gas temps.
Which leads to the next question:
2. Do you plan to "ovalize" the holes in the flanges where the exhaust studs come through?
The idea here is to allow the flange to expand under heating and not place lateral shear loadings on the studs themselves. This "ovalizing" isn't a large amount, but sufficient to avoid loading the stud. Gas leakage is avoided by having the usual exhaust gaskets; the "ovalizing" is small enough to have the exhaust stud securing nuts have sufficient area to bear on the flange itself. If one is concerned abouty proiper bearing, an appropriately-sized stainless steel flat washer can be placed on the flange under the copper exhaust stud nut.
good to see it getting put to good use!
