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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 575 |
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I have read that Lotus used several versions of the 2.2 crank over the years, are some better than others for a 2.2 conversion on our 907 JH engines. I was offered a 2.2 crank from a Sunbeam Lotus engine along with the pistons and rods, but I wasn't sure if it would even work on our JH engines. What else would need to be changed to complete a 2.2 conversion?
Dan,
Sorry about the late response, but I'm new to the forum and I'm just catching up.
Cranks for the Elite, Eclat and standard Excel were not cross-drilled. Cranks for the Esprit, Turbo, Excel SE & SA were cross-crilled on main journals 1, 2, 4, & 5 and were installed with different main bearing shells (bottoms plain, no groove or hole). If you're building a hot-rod motor, use the cross-drilled crank (or have yours cross-drilled) and the later bearing set. I'm not sure if the 911 Sunbeam engine had a cross-drilled crank or not, but I don't think so.
Later cranks (Esprit SE onward with Renault transaxle) used a ball bearing for the spigot bearing (pilot bearing), so the pocket in the back of the crank is much larger... 35mm ID. That's the only standard replacement crank available from Lotus now. For older engines, they provide a steel insert to step the bore down to the ID required for the old bearing. BTW, the ball bearing is the way to go. I've converted my engines to it, and all the local Lotus club members' cars I work on get the conversion as well.
The 911 rods and pistons will work in the 907.
Hi compression engines should have the head studs replaced with the later hi-spec Lotus parts. Pricey but worth it. The original parts were prone to stretching and subsequent head gasket blowing.
Use the later Esprit Turbo head gasket by Goetze. It's an olive-drab composite part, not a steel faced gasket like the original.
Tim Engel