Cutting pushrods down.

[KRAZYMATT]

I got my 1.3 rockers yesterday, I have 6.500" length chrome push rods from Vegas carts in the motor now. NR racing website (where I got the rockers) says I need to shorten the pushrods 60 thousandths to a length of 6.44". What's the best way beside turning on a lathe? It would be 2 months before I can get back to the machine shop... Was thinking of pulling ball end out, scribing a line .060" from end and taking it off with a bench grinder and clean up on belt sander. Also thought about using bandsaw then cleaning on belt sander. Probably be pretty tricky with the bandsaw since the blade is .030-.040" itself...

[raydhd]

Don't you think that the 60 thousands could be found in the lash adjustment?

[KRAZYMATT]

I'm not sure, haven't got out to the cart to try it, it is not very much that's for sure. I guess I will try it and set the lash to .005" pull the plug and turn the motor over by hand via the clutch to make sure there's no interference with the piston...

[Cheezygo]

I'd say that .060 cut is to keep the roller away from the edge of the valve stem. Check it closely or you will end up with a bent valve among other things.

[Cheezygo]

Not for a clone motor but the same thing for all engines..
http://www.compcams.com/Technical/In...20Geometry.pdf

[Shepard]

How are you going to polish the tip of the push rod back to its mirror finish?

[KRAZYMATT]

Well I tried it with them at stock length, I have the recoil starter and the electric starter on my cart, I did the intake side then used the recoil to crank it over to do the exhaust, after having both done it would not crank over. bent the intake push rod. pulled the rockers, rods and plug and it turns over fine, got frustrated and lef, hope I didn't bend a valve also. gonna put stock rockers and push rods back in and check nothing else is damaged. if its good gonna order the proper length from vegas carts since I already gotta replace one. do I need to use the guide plates still with the hardened pushrods?

[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.

[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?