Blackship

I red here that the GM nominal dimensions on LS7 heads (pedestal heigths, rockers fulcrums to seats axis) are not exactly known (not published by GM at this day).
Is it a true assertion ?
If response is yes, how aftermarket heads manufacturers did design these dimensions for their production ?
Sorry for my poor english. Hope that question is still understandable.

ClothSeats

I don't know if those dimensions are public information, but if not, the usual methods of replicating them would be with measurements and/or computer scanning.

Blackship

Way to duplicate the issue ?
Maybe the "good values" are those measured on 200kkm non modified heads lol

grinder11

A CMM would give exact results. However, if you measure 10 different LS7 heads, you may get 2 or 3 off the wall readings. So the question becomes which head is the norm? Which set of dimensions are correct as to what the engineers were specifying? Nobody seems to have the factory spec, so the aftermarket probably just engineers everything on a clean sheet of paper.......

Dandy97

As a member of SEMA after market manufactures can get access to the OEM's CAD data and drawings. It is a very expensive annual membership and you pay an additional amount for each vehicle that you want access to.