Running XPZ, Stage 3 ZZP heads (only milled .005), OEM L26. Have push rods 7.050 Exhaust and 7.100 intake. I am having a hell of a time figuring spacer thickness required. Anyone with this set up remember what they used to get me in the ballpark? Right now I have .063 pedistal spacers installed.

But I am having a hell of a time getting accurate preload as there is not much room to fit my hands in there to spin the push rod.

Here is what I "think" I know:

.1" extra valve height (longer per ZZP) / 1.6 = .0625

.035" (radius) less on the base circle for the XPZ

7.02 - .0625 + .035 -.005 (head milled)= 6.9875" ideal pushrod without pedistal spacers

Now I use 7.050 exhaust and 7.100 intake so I am gonna use middle of the road 7.075 for calculation.

7.075-6.9925= .0875 difference

How in the hell with the 1.6 : 1 ratio do I take that .0875 and figure the correct shim needed? I have a headache.

.1" extra valve height (longer per ZZP) / 1.6 = .0625

.035" (radius) less on the base circle for the XPZ

7.02 - .0625 + .035 -.005 (head milled)= 6.9875" ideal pushrod without pedistal spacers

Now I use 7.050 exhaust and 7.100 intake so I am gonna use middle of the road 7.075 for calculation.

7.075-6.9925= .0875 difference

How in the hell with the 1.6 : 1 ratio do I take that .0875 and figure the correct shim needed? I have a headache.

I am thinking: 1.6 x .0875 = .0546875
.0546875 + ( .0328125 ) = .0875
.0546875 - .0328125 = .021875
.021875 / 2 = .0109375
.0109375 + .0328125 = .04375 (pedistal shim needed)

Like I said, I have .063 in there now. Maybe that is too much? Have to look at that when I get home.

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01 GTP SE Sold. 89 Mustang Vert 331 T-trim

Worked fine with .040 shim. Car fired right up.

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01 GTP SE Sold. 89 Mustang Vert 331 T-trim