Quote:
Originally Posted by john walker's workshop
Swap the mod S cams in the above engine for a 66 solex grind and you will get your bottom end back.
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I would have to disagree.
The increased compression of my build allows/requires a little more cam than the Solex. (I am a great fan but not for this build)
The increased lift, similar duration numbers and wider lobe center leaves the Mod"S" cam a far better choice. These are small motors that want to breath to run with spirit.
The wider lobe center will
1) Raise torque to higher rpm
2) Reduces maximum torque
3) Broadens power band
4) Decrease chance of engine knock
5) Decrease cranking compression
6) Idle vacuum and quality is improved
7) Valve overlap decreases
8) Increases piston-to-valve clearance
Given the increased volumetric efficiency of the higher lift cam, low end performance numbers are still higher than the Solex given all other things being equal.
Porsche 911 Solex I/E 248/236 242/230 .455"/.414" 97 4.2-4.6 mm
DC 40 "MOD-S" I/E 266/249 259/242 .474"/.440" 102 4.5 mm