View single post by Esprit2
 Posted: 01-16-2017 11:21 pm
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 300
DonBurns wrote:
The club store mentions they are necessary to avoid valve float (bounce?) but no mention of the binding issue, but I have to assume the springs are correct.Hmmm... the stock valve springs will rev beyond the stock tappets' and rods' max rev limits, so I don't see higher as being an issue. But that's picking nits... the real point is that the upgraded valve springs are also necessary to avoid going coil bound-with the high lift cams. You've covered that base.

DonBurns wrote:
I wonder if the final compression of 9.6 is due to the decking work.It's like touching a spider web... everything affects everything. The compression ratio will vary with all those things, and I can't tell you from here what is dominating in your engine. If you really want to know, then CC the combustion chambers, and add the incremental volume of the thicker gasket.

DonBurns wrote:
now I'm wondering if they put the cams in the right place.Are the cam's "Lotus" OEM, or regrinds? Lotus marked the cam's exposed shank... the part visible between the back of the pulley and the front of the cam carrier/ seal. The 104 cam will have a string of 444444444...s stamped around the shank, and the 107 will have 7777777...s. If they're regrinds, then you're at the mercy of whomever reground them... did they re-mark the cams in any way? Usually not. Failing that, the lift is the easiest to measure identifying trait... you're on the right track.

C-cam = No grove/ no marking.
D-cam = One grove.
E-cam = Two grooves cut around the shank.
104 cam = 444444444444....
107 cam = 777777777777....
The part number cast into the camshaft is for the raw blank, not the ground cam. It's the same for all.

Tim Engel

Last edited on 01-16-2017 11:22 pm by Esprit2