I pm'ed RalliartonLSD for the size and now waiting for a reply.
After further searching there is no vacuum lines on the transmission, everything is controlled internally by the ECU so now I have another reason to reflash my ECU.
As for the shims, I don't have to take the head off, there is a tool that can be rented that you connect to each cylinder and blows in air to hold the valves up.

 

alright I talked with delta and the shim size recommended is #10 stainless steel washers , you'll need 16 ( 16 valves ) and tighten the springs 2-3 thousandths more than oem specs

 

Good info, but are you talking about the valve lash here?

 

Just a word... tightening up the lash and shimming the spring isnt going to increase the vaccum on your motor. As for the shims, these need to be hardened steel the pressure on them is a good amount and they will wear if you use a #10 washer---so not a good idea. The increase in spring pressure I am puzzled about-- unless you have coil bind and this needs to be remedied and that then could effect vaccum. But then they are recommending decreasing the valve lash ( tightening it) and that would add a little durantion all the way around and increase any binding you are getting at the springs---so not likely the issue. You need to look at timing, cam and ignition and see if you can increase vaccum--- check you filter set up as well, look for possible bottlenecks--that the only way your going to find you prob.. and see about a tune. BTW--did you disconnct you battery and reset the ecu? If not start rt there. maybe you find a new vaccum source on the manifold for the kickdown. Buy a vaccum gauge and start the process--

 

Guys there is a little confusion in here. The shims are not to fix the vacuum issue. The shims are only to improve the springs stiffness.
Regarding the vacuum, the only way to fix it is with a reflash (waiting, waiting, waiting for the software release).

 

thanks for clearing that up Dacib and delta has had people use the stainless steel washers in dsm's with over 500whp so I'm I'm sure they can handle our NA motors

 

What effect do stiffer springs give?

 

once you have the upgraded cam, doing this will
help to quiet down the valvetain.