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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 575 |
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How are your cam's timed. The early J-H timing was 115 IN / 115 EX, and that reduces output by 10 Hp. Later it went to 100 IN / 110 EX. Both of those are emissions settings, and not desirable. The design-correct C-cam timing Lotus used in the early 907 is 110 IN / 110 EX.
Does Street Prepared restrict the cam timing to stock, or can you make adjustments? At least update/ backdate? If that's not a problem, then try re-timing the stock C-cam to at least the design-correct 110 / 110, or more aggressively to 104 MOP IN / 110 MOP EX.
Unfortunately, the latter would require a new 104 MOP green-dot pulley for the intake, and they're expensive for what you get. Maybe Mike Taylor can set you up with a serviceable used one. 115 and 110 co-exist on the same pulley, whether both are marked or not.
Not that I would ever suggest cheating in anything but the holy NASCAR-biblical sense, but the C-cam has 272 degrees of duration, and the 104 cam has 272 degrees of duration. The devil is in the details... just sayin'.
You're right to be concerned about the cast iron tappets. I've seen way too many cracked ones in recent years. Steel replacements are available, but a set of 16 gets expensive. On the other hand, one broken tappet in a running engine gets very expensive in a heartbeat. But then, you now know that... tell the others.
Regards,
Tim Engel
Last edited on 04-28-2017 07:09 pm by Esprit2