Quote:

Quote:

This is the roller motor 5.9L Magnum with a .520/.544 Hughes cam, stock lifters/valvetrain/pushrods, RHS heads, and stock valves.
Not even a .010" feeler gauge fits between the valve stem and rocker arm


For starters with a hydraulic roller lifter motor you should have preload not lash and you should therefore not be able to any feeler gauge between the rocker and valve stem.
Did you use the valve springs that are compatable withthat cam lift and did you check for coil bind. Alos did you check to make sure that you have enough cleanarance between the valve spring retainer and the valve guide and seal so that it does not hit. In boththe above instances you need at least (preferabley more) .060 more travel at full valve lift if you don't you have potential problems and could very well do as you have explained your problem.



Don has some good points. when I originally read this thread (especially about the part of the bent pushrod), I thought of maybe coil bind or other hard interference. .544" is A LOT of lift for a magnum style head. my OEM magnum heads had .54" of travel before the seal hit the valve locks, about .57" after the valve job (where I asked to sink the seats a little for more installed height). for your lift, Ideally you'd want at least .58" or more.

I presume you're running hughes 1110 springs? I measured stock springs and they only have about .480" travel before coil bind, and are very soft w/low seat pressure, and wouldn't be able to control an aggressive lobe like the hughes cam has. I am running 1110 springs with 2.2L retainers and magnum locks. I only got 1.60" IH before the valve job (~1.63-1.64" after). The hughes springs coil bind at 1.04, so I had .56" (now .59-.6") travel before coil bind. I'm running a cam with .506" lift. with your cam I'd want AT LEAST .59" travel, preferably .6-.61".

another possibility is the magnum hydraulic lifters don't have a lot of plunger travel, only in the .060" range. maybe with all the parts swapping, head gasket thickness, if the heads or deck were milled, if the valves were sunk, the new cam's base circle, etc, maybe your pushrods are either too long or too short. to short, you might not have enough preload on the cam's base circle, making the ticking noise, which shouldn't affect idle quality, unless the pushrod pops out of the lifter or pushrod cup and bends. Too long, and you may have excessive preload to where it bottoms the plunger and hangs a valve open, or where a valve hangs open if a lifter pumps up.

I lucked out (kinda) with my build, virgin LA318 roller shortblock, uncut (AFAIK) magnum heads, magnum rockers & lifters, and reground LA roller cam (base circle reduced ~.060 to up the lobe lift from ~.26" to .316"), and valves sunk .030" (which raised the height of the valve tip, requiring shorter pushrods) everything worked out that the stock magnum pushrods put my lifter preload right at .020-.030", about mid travel of the plunger. I say I lucked out only kinda, because I had already bought a set of 6.936" pushrods (stock according to my '97 FSM are 6.9-6.916") figuring I'd need longer pushrods with the reduced base circle cam.

and as someone else mentioned about the tick. make sure it's not an exhaust leak. a lot of times they sound like a lifter/valvetrain tick.

another thought on the miss/poor running. double check the reluctor gap in the distributor. it should be .008" measured with a brass feeler guage.

one other thought, when you put this together, did you check valve to piston clearance? .544" is a lot of lift for stock pistons w/o valve reliefs....I wonder if the valve is kissing the piston?

Last edited by patrick; 08/06/09 10:43 AM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)