View single post by Judson Manning
 Posted: 05-06-2008 06:00 pm
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Judson Manning

Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406

There may be an explicit part number for the accessory housing sprocket, but I'm not aware of one.  From memory all I've seen is just another cam sprocket mounted in that location.

The 1975 Spec 4 JH used a 100/110 timing mix while later Spec 6 & 7 kept with 110/110.  In 1980 the California Spec 8 went to 102/110.  My guess is that the 100 & 102 mixes were specific efforts to increase intake overlap to meet certain California NOx emission requirements with the original 'C' camshaft.  Installing a blue-dot sprocket on Intake alone would yield similar results.

The guys at posted dyno results of two 104 cams (same duration as the JH 'C' camshaft) utilizing 104^LC (blue-dot) sprockets.  Comparing their dyno results to others suggest peak power moves up from 6200rpm to 7200rpm.  Of course the lotusbits guys were running a fully ported head.

On an otherwise stock JH, switching to 104^LC sprockets would shift power potential up 1000rpm at the expense of low-end torque and drivability.  Concurrently, the increase in valve overlap decreases the dynamic compression ratio.  Without switching to higher compression pistons there would be a net loss across the entire rev range.