FullSizeJeeper I finally got my heads back from the machine shop and the are now on the block. (74 AMC 360) Had them milled .25 + the thickness of the guideplates, tapped for studs, and have a set of Crane AMC roller rockers. Now I'm trying to determine the pushrods I need and finish this project up. I have an adjustable pushrod to help determine my needs. I set it at +.10 and checked the valve opening on the exhaust valve versus a standard length pushrod. They are the same. Is there a method to determine if I need longer or short than standard pushrods? When the lifter is on the bottom of the cam lobe, I have no preload on the hydraulic lifters and set the lash to zero then tighten a half turn I should get no valve opening correct. Crane's instructions say to tighten from 1/2 to whole turn. Well thats kinda of a large range. Any info on the best method to adjust the rockers? Do you want it tight to the poit of just opening the valve? Any help would be greatly appreciated.
82Waggy When the valve is closed, the roller tip should be slightly behind (towards the pushrod) the center of the valve stem. If it is on center you need to shorten the pushrod to rock the roller tip up and back. When the valve is at half lift, the roller tip should be centered on the valve stem. When the valve is fully open, the roller tip should be back to slightly behind the center of the valve stem. Use some machinest dye or a black marker and color the top of the valve stem. Cycle the valve and see where the wear point is and adjust pushrod length accordingly. This should be checked with the rocker adjusted to zero lash plus 1/2 to a full turn. Also check for sufficient clearance between the rocker trunnion and rocker stud, between the rocker and upper spring retainer, and for spring coil bind throughout the full range of travel - should be at least .060" clearance between the spring coils at full compression to allow for harmonic vibration and heat expansion. Have not used Crane roller rockers myself but hear they are not quite correct length for an AMC.
FullSizeJeeper Thanks for the info, The rocker stays center the best with +.1 (7.9") pushrod length, A little far back with the standard length. Was going to get the Summit hardened pushrods for SBC at +1 (SUM-G6400100). Anyone got experience with those. The price is right, says they are good up to 300+lbs. I'm running a summit 8600 cam and Edelbrock AMC springs with the Crane AMC 1.6 Rockers. iI checked the clearances and they are good. The only other issue I'm wondering about is Adjusting the rockers. 1st time, want to get them dome right when engine is going together. 1) I'm sitting them to zero lash with the lifter on the bottom of the cam lobe then turning a full turn. But I'm getting some sideplay and they seem pretty loose. 2) Am I setting zero lash correctly? Tight adj nut until the pushrod just starts to depress the hydraulic lifter (back it up to zero or try again if needed). There should be no clearance between the roller tip and the valve and no preload on the lifter correct? 3) I'm using a cam and lifters with a couple 1000 miles on them, some of the lifters are very tight, cannot move plunger (no preload) others compress easily. Is this normal, some just bleed out? They have been sitting for about 2 years (1 in fogged engine, 1 in box out of engine) 4) How much play should the rockers have, and side to side motion when the lifter is down? Any when they are up? I have not adjusted a set so don't exaclt know how they should feel. The intake and exhaust are till off, so can check things very easily. Any boady have a simple and dirty adjusting method?
82Waggy It sounds like you are finding zero lash correctly. Should be able to spin the pushrod with no end play at zero lash. From there you adjust 1/2 to a full turn down. The geometry I described results in the valve stem being tangent to the center of the roller tip arc, and therefore the least amount of travel across the tip of the valve stem. It also places the fastest rate of acceleration at 1/2 valve travel. Hard to say if your lifters are OK from what you describe - it is possible that some are full of oil and some are not. Are you running guideplates?
FullSizeJeeper Yeah, I got a set of David Stahl in PA, they are hardened. These summit pushrods I'm looking at are also hardened and welded tipped. I'm not sure the springer pressure, my machinest does good work so I left the head work to him after I ported and polished. I'm wondering if the summit pushrods will handle the load from the summit cam and edelbrock springs?
FullSizeJeeper Thanks for the help, the picture is great. Used bluing to mark. 7.9 puts me on center. I ordered the Trickflow over the summit pushrods. Painting the heads and block today and will work on the rocker adjustment over the weekend and get this thing buttoned up.
