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cam install???

Discussion in 'The Garage' started by gambit420s, Jun 13, 2005.

  1. gambit420s

    gambit420s 1/2 ton status

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    i'm installing a comp hydraulic lifter cam and timing set on a 89 350 G truck block

    i intstalled the crank sprocket with a bolt threaded all the way to the hex(as closed to a "tool" as i can afford) and a nut to draw the crank sproket down, i tightened it as much as i dared to seat it(11/16 wrench+330lbs of me=prob about 75-100 ftlbs on a lubed thread)

    the correct faces of the gears(with timing marks) are facing foward so the marks are visible

    the cam and timing set are correct for the engine block being used(i double checked even thought i dont think there is a difference for old vs later blocks)

    things ive noticed:
    1. with the cam gear installed and hand tightened; the gear doesn't seem to bottom out on the nose
    2. even not completely seated on the cam, the cam gear wants to be pulled foward about .050 to .100 to align the faces of the gears

    questions

    1. will torquing the cam gear bolts to spec seat the cam gear? i measured the #1 bearing and the inside of the gear and the gear is about .002-.005 larger inside the recess

    2. how far is the cam supposed to float forward and aft? when pulled forward to align the faces of the gears; the cam lobes appear to be centered in the lifter bores

    3. did i seat the crank gear enough? to much?

    i dont remember noticing any of this when i replaced the timing set on another 350 bout a year ago, although it was installed in a truck, and was otherwise complete(lifters, distributor, etc.) and i just slapped it together... :confused:

    any help would be greatly appreciated
     
  2. Wes Harden

    Wes Harden Registered Member

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    sounds about right

    Tha cam on sbc's does walk a little you can get a timing cover and matching button to stop this. When the distributor is install the cam will move less. It sounds to me like you seated the crank gear, should be against main bearing juornal. And torquing the cam bolts to spec should draw the cam and gear together.Doulbe check thou, gear may have been machine wrong.
    Good luck
    Wes
     
  3. gambit420s

    gambit420s 1/2 ton status

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    yeah but i dont think a button/new cover is required, please correct me if i'm wrong but this is really only needed if i was retro-fitting a roller cam, because of the slight taper machined into the lobes of a flat tappet cam, the lobes push back, and the cam gear rides against the block face.

    ok ive been looking at it some more and i think ive answered some of my own previous questions

    1. solved just needed a lil oil and tightening the bolts with a socket
    2. still wants to move more than i would think is right, but no dist or lifters/p-rods/rockers; so probably ok
    3 it appears to still have a gap between the crank gear and the snout where it steps up and radiuses in to the #1 journal; leaving the faces of the gears off a little

    still have this question:

    3. should this be seated flat against the step?

    It would seem to solve my prob but i didnt think i could do it without hurting anything, maybe time for the "proper" tool, just not enough draw with the crank bolt sized threads...

    i was using a fine thread gr8 tap(full thread)bolt threaded almost all the way in(backed off 1/2 turn not to stress the threads against the crank) with 3 316 s/s washers(bearing), a gr8 heavy hex nut(bigger wrench size and more load bearing surface), and a spacer(to make up for balancer) all lubed w/moly grease and 30wt on the gear and snout.

    i thought the fine thread w/lube would give me enough drawing force but i guess not

    tomorrow(well later today), ill try with a box-end crowsfoot and a bar, unless some one can point out something i've missed

    crank snout was clean, burr/nick free, gear is new comp #2100, has new/correct keys in snout
     
  4. Mad-Dog

    Mad-Dog 1/2 ton status

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    Only roller cams will walk forward in the block and are required to use a bushing that seats against the back of the timing cover,
    flat tappet cams are machined with a slight rear facing angle which keeps the cam pressed against the rear cam plug.

    I'm assuming the cam he is installing in the '89 block is a roller version which requires the anti-walk bushing,
    timing chain/gear sets are the same for either style cam.

    The only thing i can think of is that the crank gear is not fully seated or there is a shim on the crank snout that was designed to work with the factory gear but not with the aftermarket gear and is locating the crank gear too far forward.

    You also may be thinking that the new cam must sit all the way in the block with no backlash (not true),
    as long as the cam journal does not extend past the bearing surface.....the journal should be centered in the bearing during normal operation.

    Visually look into the lifter bores and make sure the lifters will center themselves on the cam lobes.

    An often overlooked process when changing cams/lifters, heads/gaskets or assembling a engine after the deck or heads have been milled is (Checking Pushrod Length) for correct rocker geometry.

    This is the icing on the cake that will separate your engine from the others....to be blunt at mid lift you want the rocker tip centered on the valve stem.

    Say that the lift at valve is .500" or 1/2 inch so mid lift would be .250" or 1/4 inch...this is where the center of a standard rocker or the center of the wheel on a roller rocker should be centered on the valve stem.

    adjustable pushrods are the easiest way to determine the correct length if you need to change the pushrods.

    If guide plates are used they can be adjusted slightly to correct any alignment problems that you may encounter if not using self aligning rockers. :)
     
  5. gambit420s

    gambit420s 1/2 ton status

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    i am installing a flat tappet cam (comp 12-231-2 xtreme 4X4)which is why i dont think a button is required
    this is what i am thinking i'm going to try to seat it completely, here in a minute.
    with the cam gear installed and pushed back onto the gear's thrust surface #2-#5 journals are centered on the bearings. the #1 journal is wider than the bearing but it is flush on the back, with the protruding nose recessed into the cam gear
    with the cam pushed back against the gear's thrust surface, the lobes are centered in the bore
    i did not have the head or block surfaced, but w/new head gasket i will check the pushrod length
    i will be using self-aligning rockers

    thanks dog
    if all else fails ive got a x-large BFH..... :grind: :weld: :hack: :whistle:
     
  6. Mad-Dog

    Mad-Dog 1/2 ton status

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    That is a very mild cam you have chosen,
    it will make great torque down low.

    Let us know how it runs when you are up and running :grin:
     
  7. 3 on the tree

    3 on the tree 1/2 ton status

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    Dumb ?- did you give the crank snout a LIGHT polish with some emery cloth? I have had similar problem, and a little emery cloth and elbow grease cleared it up.
     

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