View single post by discogodfather
 Posted: 04-11-2020 09:16 am
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discogodfather



Joined: 09-17-2007
Location: San Francisco, California USA
Posts: 188
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I was surprised to find some fairly clean and tidy piston heads that wiped clean when I pulled the heads off this 73' custom built engine. Heads have had a lot of work and running 104 cams, put out very good power (I was told 190hp when I bought it, dual Weber 45's and custom headers, etc.)

They don't strike me as cast pistons and my first reaction was that they were JE's as they kind of look machined, but as I inspected further with a good light I'm not so sure anymore.

They have the strangest little light (less and 1mm) valve relief cuts. At first I thought- oh no, valve contact! But they are so clean and uniform and the engine was running smoothly with no noise, so that seems implausible that they are indentations from the valves. They seem machined into the surface.

I tried to look for some pictures of JE and some stock Lotus S1 and S2 pistons and could not find anything that looked like these. Did the older Dave Bean style look like this?

Is there any way to precising calculate compression ratios? I could borrow a friends hole gauge and measure the liners exactly and then measure the stroke, but not sure how this would work.