looking at the crow valve springs and it mentions that the VTKAU springs require the head to be machined...

what exactly is the issue..where / what needs to be machined?


E series
7332-12 1.820" 115 275, Retainer: 11700-12
7333-12 1.820" 140 305, Retainer: 11700-12

AU

VTKAU* 1.820" 125 285, Retainer: 11740-12, Collets: Stock
VTKAU-R* 1.82” 150 310, Retainer: 11740-12 Collets: Stock, Spring seat SS1456
* require machining.

Have a look at this thread:

http://www.boostedfalcon.net/viewtopic.php?f=3&t=7390&start=480&sid=04a36988b574e8dd7cbb510c965c4156

Basically to get the proper installed height of the spring, you should machine the step and use the supplied shim.

yeah some good stuff in that thread..

im confused but, he was running the VTKAU-R which are different to the VTKAU... the "-R" ones come with shims, the normal ones dont...also why is this not required on EF heads, theyve got the same step also...

for the benefit of others wondering here is the info I got directly from john at crow cams..

VTKAU = Single spring with damper, same style as EA - EF, uses stock valve stem seal with retainer to suit metric (7mm) valve 125Lb@1.82 IH...

VTKAU-R = double spring (actually a cleveland spring), needs machining to suit the inner spring. will also need a positive stop style seal on the guide..150Lb@1.82IH... approx $30 more than plain VTKAU

I could this with out machining.
Atomic retainers and cranecams big block chev spring.