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PCA Member since 1988
Join Date: Feb 2018
Location: SW Washington State
Posts: 4,625
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Henry, nice compact "peanut" combustion chamber. Did you also use a flat top piston? That's very similar to the "bathtub" shape (with one spark plug) Harley used before moving to 4 valves. Also similar to what Dick Elverud showed me in his shop. It seems you would not need 2 spark plugs with a compact chamber like that, as the flame should travel across the small chamber quickly with just one spark plug.
That's what Porsche should have done, but the hemispherical shape was carried forward from the 1960's. Heck, even VWs had more compact chambers.
Going back to the M1, I know from looking at the fatness of the lobes that the duration is increased significantly over the stock Porsche cam and it appears they have more overlap too. It would take some measuring equipment I don't have to find the LSA. And I don't think William would be happy with me if I did that.
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners.
Cars are for driving. If you want art, get something you can hang on the wall!
Last edited by PeteKz; 03-12-2023 at 12:31 AM..
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