M113 VS M113K Valve spring pressure Single VS Double

I’m busy rebuilding and cleaning the M113k heads that i will swap on my M113 5.0 turbo.   I have now the double springs from the M113k AMG and have M113 NA non AMG single springs

I have made a testing frame with a weight scall that i can meassure the pulling pressure of the spring and certain pressure levels on the springs.  I have found some info on stock M113.960 engine springs on  Catcams.com  website.

The oem spring has  a installed lenght of 38.8mm and 41kg  and a max measured valve lift at 9,5mm bij catcams at is the 75kg spring pressure .

I checked this with my measuring device and have at 38.8mm  39kg  and at 9.5mm lift it is 71.6kg  so this is a little less then catcams is giving but pretty much in the ballpark.

Now measuring the M113K AMG double springs .  At installed length it is 0,5mm less installed height at 38.3mm because the bottom retainer is 0.5mm thicker.    so at 38.3mm the measured weight is 49.1kg  at at max lift the amg cams have 10.65mm lift this is giving a spring pressure of  100.8kg.  To have a correct meassurement against the NA cams we need to look at the max lift on the NA cams.  This is 9,5mm the spring pressure on double AMG spring is then 94,2kg

Conclusion.   At installed weight  the double springs have 10.1kg more pressure.  at max lift NA cams 22.6kg more pressure. when looking to engine specific and the installed cams then M113k AMG provides. 29.2kg more pressure.  what is massive

In % this is  installed seat pressure AMG double springs 25.5%.   at max valve lift  AMG double springs  40.7%

My conclusion is.  if your going to run a small turbo on a m113 engine and having a high exhaust backpressure you should go for double springs. It is needed to not get a change on valve float.  I dont say it is not possible to run on single springs but monitor it close.

if there are any question  just ask

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