I am rebuilding my block and it and the heads will most likely be milled so, I am fixing to buy comp cam's tool that resembles a regular pushrod to get the correct pushrod length. I have read how to use it, but I'm an idiot and don't understand the directions. I am thinking I am suppose to set the length with this fake pushrod and stick it in the hole put the rocker arm on, and see if it is possible to set the correct lash. I think I am wrong can someone please help me out. Thanks alot.

 

you need a solid lifter for one thing. maybe an old lifter if u have one. u can take it apart and make it solid. i actually took an old lifter and put a couple tac welds in the corner to make it solid.

take your length checker maybe put it at stock 7.200" length first and put it in. take a marker and mark the valve tip. put rocker on the top and tighten to zero lash. turn the engine over by hand several times then take the rocker off and look at the valve tip to see where the mark is.
it should make a narrow mark in the middle of valve tip when correct.
if its off center towards exhaust it is too long. if the mark is too high towards intake its too short.
just play and adjust your checker until u get it to make the mark in the middle.

anybody feel free to correct me if i said anything wrong.

 

Why would you need a "solid" lifter. Seems to me that when you check how the rollers are striking the valve stems, that if they are not correct that an adjustable rod would merely be used and adjusted until you get the correct geometry and gets some rods that are the same length as the adjusted rod.

Perhaps that is over simplification. I know that when I got my Crower RRs that the "AD" recommended getting .50+ rods, i.e. 7.50s. But recently when my Valve Train went to hell, my mechanic changed the rods back to stock along with heavier springs. He mentioned that he thought the geometry was off and contributed to a couple of RRs coming off the stems and causing the valves to drop onto the piston. Don't really know why it happened and don't really know if the longer rods contributed, since I did not personally check the geometry. (which I should have, instead of taking someone's word to install longer rods).

Anyway, I leave it up to the experts on this score.JMHO

 

because every single person ive talked to say you need a solid lifter to get an accurate pushrod measurement.

 

Ok. Seems a bit overkill to have to mess with a lifter though. I'd follow the directions of the manufacturer of the adjustable push rod before going to all the trouble of using a solid lifter. If you use a solid lifter and then re install a stock hyd lifter, seems like your geometry could change.

I'll bet he doesn't wind up using a solid lilfter.

 

With a regular valvespring I am sure you would need a solid lifter since the hydraulic will not have pressure to keep it pumped up. Alternately wouldn't a very light spring work still need enough tension to hold the valve and provide enough resistance to get the roller to mark the tip but wouldn't the spring in the lifter be enough to hold it against a light valvespring like that.

 

101: The job of the cam is to send a message to the valves to open and close during the strokes to get as close to the best IMEP (Indicated Mean Effective Pressure) as possible (which is a mathamatical calculation based on the difference between the -torque of the upward stroke to TDC and the +torque (or power stroke on the way down) The closer to a perfect pressure the more power. The way your valve train operates has a significant effect on the goal.

Having said this about that (which of course, I haven't a clue as to what I just said) one of the important components is the length of the push rod.

Even with hyd lifters, when you have the cam on base circle and both valves closed and 0 lash, your roller should be in the middle of the valve stem (not to the side) when you wriggle the RR. Basically you want the roller to hit the valve stem on the inboard 1/3 of the valve to the outboard 1/3 on the vavle stem.

If you measured the angle of the roller trunion (the little round axis thingy in the middle of the roller) you should get a 90 deg angle beteen the middle of the trunion and the tip of the valve stem at mid-lift.

Bottom line, you want the cam to send as clear a message to the valves as you can get to maximize your cyl pressure for the best power. If you rods are not the correct length you risk having them move off the stem at higher revs increase the possiblilty of them hitting the keepers, breaking them off and dropping a valve (at the extreme) less extreme results could be compromising your engine life and not getting the power you should.

I now leave it up to the experts to correct me--but I still don't believe it is necessary to use a solid lifter to reach your goal of correct geometry.
Thank you for your support. JMHO

 

use a marker or a colored touch up paint for cars works well too. use whatever you choose paint the top of the valve with. then assemble your valvetrain and tighten the rockers correctly to lash. you must have the cam and lifters in too. (at leas 2 lifters will work). from there, turn the motor over a few times. if your wear pattern on the rocker is not in the center of the valve, you will need a shorter pushrod.