Randy WS6

iTrader: (69)

I checked all the exhaust valve height and its at 1.838". Ive been reading on here the way to check the desired height is to , Check the valve height with the retainer to the spring seat its is 1.837" then put the spring in a vice and tighten down till coil bind witch is 1.050" + .050" for coil bind = 1.100"+ cam lift .632= 1.732"- Valve height 1.838" = .106" shim. ,My spring pocket is only .125" deep. so it only leave .019" to hold the spring centered.

Now if i used the cam specs, it said the valve height should be 1.80"then ill only need a .038 shim.

What should i go with. I have 1.060" ext & 1.100" int valves. The weight of the valves maybe causing me very bad valve float

405HP_Z06

iTrader: (11)

This depends on which valve springs your using. For example, if you were using Patriot Extreme's you would have the following:



With these, you would want to install at 1.800" because of the high seat and over the nose pressure's. As seen above, your looking at 155 on the seat and almost 400 lbs. over the nose. This maintains the .060 minimum coil clearance and leaves .018" 'on the table'. Not a big deal.

Randy WS6

iTrader: (69)

Thanks a lot. I guess ill go with the PP Extremes ,I was using PRC's

405HP_Z06

iTrader: (11)

Supposedly the PRC Platinum's and Patriot Extreme's are the same spring. Do you have the PRC Gold's now?

Randy WS6

iTrader: (69)

Ill still haft to shim because my valve spring height is at 1.838" so if i shim it .057" ill get the .060" clearace plus the 1.80" spring height.

Randy WS6

iTrader: (69)

PRC Platinum's .I put them in a vice and the coil binded at 1.050" and i herd they were good to .670" lift. Is this true ?

405HP_Z06

iTrader: (11)

I show the coil bind height for the Patriot Extreme's to be 1.090. This would mean the maximum lift would be .650, assuming .060 coil clearance.

Make sure your recording spring coil bind accurately, but if 1.050 is correct than at 1.800" installed height the maximum lift would be .690".

Concerning valve spring shim height, if your measured installed height from retainer to spring seat is 1.838" than to achieve 1.800" you need roughly a .030" shim. If you use Isky part number 6shimkit than you can use 2 each .020" shims.

Randy WS6

iTrader: (69)

Im a little comfused , PP Extreme is rated at .660" lift https://www.patriot-performance.com/...&cat=51&page=1

405HP_Z06

iTrader: (11)

What they did was reduce the safety margin from .060" to .050". Installed at 1.800" and using a .050" safety margin you can achieve .660" lift.

(1.090 coil bind + .050 safety margin) - 1.800 installed height = .660" 'safe' valve lift.

I prefer to run .060 to .100 coil clearance, but that's just me.