You really need to read up on valvetrain geometry if you think adding guideplates will affect pushrod length.

 

Stock lifters. And what is this tapered stud your talking about.

 

I can't tell, but it appears the studs you have are flat style like this:

That allows the rocker body to bottom out onto the stud. If not fixed it will cause serious damage to your valvetrain.

You need tapered studs. You'll notice there is a shoulder. That allows the rocker to sit higher to clear the bottom of the stud:


Get them and recheck your PR length.

 

That was the point is was making also . If your running stock studs they will cause this problem on rockers , It happen to mine

 

Have a 2nd set of eyes help you out. You may have more than 1 issue

 

True, but adding guideplates to an engine that doesn't require them, and combining them with OE rocker studs, will move the shank of the stud approximately 0.060" closer to the bottom of the rocker arm. This could cause a clearence problem, even if the pushrod length was correct.

 

I've had scorpions touch with tapered studs, when a pushrod for bent (effectively making it too short).

I would bet its a pushrod issue, but its just another reason I don't care for scorpions...