Cutting pushrods down.

[KRAZYMATT]

I change from the stock rockers which are I think 1.1:1 to 1.3:1. The point of contact for the pushrod is about 3/8 - 1/2 closer to the pivot fulcrum / rocker stud. Just moving it alone changes the ratio to the 1.3:1, then the extra length pushes it that much further. I hope I didn't bent a valve or hit the piston... Think leverage.

[Shepard]

This is my concern -- valve piston hit --- going to the 1.3 ratio rockers will increase breathing ability. At the same time how close are you from metal to metal contact?

[raydhd]

I have 1.3s on now.There just billets not rollers.I am using the 460 not the 420.The 420 has way more clearance.On top of that my head is milled .075.The only issue was with coil bind on the earlier valve springs with the torque cam.

[KRAZYMATT]

Originally Posted by Shepard

This is my concern -- valve piston hit --- going to the 1.3 ratio rockers will increase breathing ability. At the same time how close are you from metal to metal contact?

This is what I am worried about too. I think 1 of the valves may have been hitting the piston which caused it to bend the push rod... Like you said at 1.3:1 it's already close, the extra length may have caused some interference.

[Cheezygo]

Originally Posted by raydhd

Any stud mounted clone rocker still needs the guide plate to keep the rocker in line with the push rod.What I don't understand why a 60 thousands longer push rod would be any different than a shorter one as everything would have more clearance as long as you moved the rocker arm up the rocker stud to get the proper lash unless it interfered with the valve cover.Maybe there is something I am not seeing here, but too short certainly will cause problems but 60 thou too long? P.S. Maybe Aaron or Geoff will jump in here and help me see where my thinking is wrong.

My guess, Because the pushrods were 1/16" of an inch too long which had the geometry off. That puts the roller too far over center of the valve tip, then when it is cranked over and the valve opens to full lift the roller rolls off the edge of the valve and binds up. Take a look at the link I posted earlier.

[KRAZYMATT]

Got a section of 1/4" 4130 tubing, Gonna try to make up a new set shorter than stock. hopefully can get to try them out this weekend.

[KRAZYMATT]

Do I need to change the guide plate out when I change the push rods? They seem snug in there compared to the oem ones. The ones I have measure 1/4" on the OD and are chromoly.