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Cam Reinstall 84 308

Discussion in 'Technical Q&A' started by Wildcatfans, Jun 24, 2004.

  1. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    I'm at the half way point on my 30K. I had some difficulty getting the cams out of the car due to the pulleys being on the cams thus not allowing me to remove the rear fiberglass timing belt cover. The rear bank being the most difficult due to the fuel distributer beign directly over the cam pulley. With the cams removed I unbolted the pulleys and replaced the o-ring. It is now time for reassembly.

    Is it recommended to reattach and retorque the pulleys before reinstalling the cams (and fight the belt cover) or set the cams in place then slide on the cam seal block (the one with the inner cam seal and outer o-ring), belt cover, then pulleys? If the pulleys are attached first, what is the best method for installing the cam seal block without damaging the inner seal?

    I did find a good way to remove the cam pulley bolts. Wrap the old belt completely around the pulley, take up all the belt slack and put the belt in a bench vice. It will hold the cam pulley in place as you us an impact wrench to remove the bolt. Have someone else hold the cam so it doesn't fall to teh floor when the bolt comes off.

    Any other advice at this stage of reassembly is greatly appreciated.
     
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  3. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    Make sure the flywheel is lined up on the PM1-4 mark.

    Also, make sure that the notches on the upper back of the cam drive gears are lined up with the notches on the timing cover. If not, rotate the engine around to PM1-4 again, this should line them up.

    Slip the cam seal housing w/o-ring on it onto the end of the cam. Be careful to not let the tension spring on the inside of the seal slip out of place.

    Smear a few drops of oil all around the o-ring & put a couple of drops into the o-ring groove in the head.

    Put a few drops of oil on each of the cam journals & spread it around the journal surface of the cam. A synthetic oil such as Castrol Syntech is best because of it's high film strength. Be a bit generous, this is all the lube the cam will have until the engine is running & has built up oil pressure.

    Lay the cam & cam seal housing into place, making sure the cam marks are at 90 degrees to the cam cover mounting surfaces.

    Lay the cam caps in place, & put the nuts on finger tight.
    Make sure the marks on the cams are pretty close to being aligned with the marks on the cam caps closest to the cam gears.
    (Note that the cam caps and head are numbered. Align the caps with the numbers on the caps next to the numbers on the head.
    The rear bank cams will just about drop into place as all the valves will be closed or almost closed.

    Caution: The REAR bank has pistons on TDC, so be very careful to keep the cams on the marks as you tighten the caps. The intake cam in particular will want to shift a few degrees on you. A strap wrench on the pulley is a good way to keep the cam aligned.

    The front bank exhaust cam has one of the valves fully open when it's on the mark. However, the pistions are in mid-stroke, so there's no possibility of piston-valve interference. (You can safely rotate the forward bank cams 360 degrees, which is handy for setting up the valve clearance).

    You just lay the forward bank exhaust cam in with the mark roughly 30-40 degrees advanced off of the mark (ie: angled towards the rear of the car). The cam will naturally find a position. The intake cam will find an 'agreeable' position much closer to the mark.

    Working from the clutch end of the engine, install cam caps & catch each nut a couple of threads.
    Then go back & finger tighten each nut as much as you can w/o a wrench.

    I seem to remember that it was only one or at most two of the caps on the pulley end of the cam that I couldn't start the nuts.

    Once you've got every nut on that you can, start at the pulley end of the cam & work toward the clutch end of the cam, tightening each cap nut ~1 to 1-1/2 turns. Thus keeping uniform pressure along the length of the cam. It only takes a couple of passes until you can get the nuts on the last cap.

    At this point, the cam is still cocked upwards towards the pulley end. Make 2 or 3 nut tightening passes as described above, except that you level the cam out by turning the nuts between the pulley end & middle of the cam an extra 1/2 to 1 turn. Watch the amount of thread protruding thru the end of the nuts.

    Once yo've got the same amount protruding thru all nuts, the cam is leveled. Make multiple passes tightening 2 turns/nut on each pass until the cam is snugged into place.

    This gradual uniform tightening is very important as the cams are very brittle. Non-uniform pressure from aggressively tightening the cam caps moving from one end toward the other has been known to snap cams in two!.

    While tighteningn the cam caps, make sure the o-ring is slipping into it's groove & isn't getting pinched/cut by the sharp corner where the bottom of the o-ring groove intersects the cam cover-head seam.

    Once you've got the cam caps tightened all the way, align the cam marks & torque the cam caps down. The front bank cams will try to rotate on you. Exact alignment of the front cams isn't too critical at this point, however the rear bank cams must be kept aligned.

    Once you've got the cam caps torqued down, slide the fibreglass dust cover over the end of the cams.

    Slip the cam gears into place, make sure the alignment pin goes into the same holes in the cam & the gear that you took it out of.

    Now, tighten the cam gear retaining bolt finger tight.

    While keeping the cam-cam cap alignment marks lined up, slip the belt into place. (You may have to rotate a cam slightly out of position while slipping the belt into place, but once the belt is on, the marks must be lined up.)

    Release the tensioner bolt & rotate the engine over 2x by hand. The cam marks should still be lined up. If they aren't lined up, most likely the cam is off by 1 tooth.

    Repeat until the marks stay lined up after the 2 rotations.
    Then rotate 2 more times & make a final check.

    If you can't get the marks quite lined up by shifting +/- 1 tooth, then you're going to have to try the cam alignment pin in different pairs of cam-cam gear holes until they are lined up. Unfortunately, if you have to do this, you'll probably be removing & reinstalling the cam gear (s) & belt & rotating the engine several times till you find out the right combination. (This shouldn't be necessary if the marks were aligned prior to disassembly, and the alignment pins were re-installed in the original cam & cam gear holes. However, it's all too easy to not be able to reconstruct the original hole pairs.)

    Tip: Use the solid end of a drill bit the diameter of the alignment pin as a temporary alignment pin. (Try ~13/64, but I don't have my notes handy.) Tape the flutes with masking tape to form a handle. This will let you try hole combinations more quickly. Once you've found a combinatin that leaves the marks aligned after rotating the engine, you can mark everything & replace the drill bits with the alignment pins.

    One of the reasons you don't want to torque the cam gear retaining bolts down before installing the cams is that you may need to reposition the alignment pins in one or more cams.

    Once you're satisfied with the aligment after rotations, turn the engin over 2 more times. Notice that the tensioner moves inwards (towards the side with the belt) & outwards slightly as the engine rotates. When the tensioner is at max inwards extension, lock the tensioner in place by tightening the tensioner bolt to the specified torque.

    Now rotate the engine 2x again. The tensioner shouldn't move, & the cam-cam cap marks must be lined up.

    (Yes, it's as tedious as it sounds!)

    Now, put the engine in 5th gear, & lock the parking brake.
    Then rotate the engine until all of the slack is taken out of the drive train. Using a slow steady pressure on the torque wrench, torque the cam gear retaining bolts to the specified value. The cam belts will hold the cam gears against the torque.
     
  4. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,033
    socal
    [QUOTE=
    Is it recommended to reattach and retorque the pulleys before reinstalling the cams (and fight the belt cover) or set the cams in place then slide on the cam seal block (the one with the inner cam seal and outer o-ring), belt cover, then pulleys? If the pulleys are attached first, what is the best method for installing the cam seal block without damaging the inner seal?


    engine at #1 TDC!

    Put the cams in first with cam lined up with journal marks

    use cam covers to drive valves to their tensioned position careful to leave marks closely aligned so as not to bend valves. matchbook cover one journal cap to hold cam from turning.

    check your marks!

    put on cam cogs with no pins but light cam cog bolts in cams

    put on belts and release tensioner. everything will snap into place and you can now repin the cogs to cams.

    remove matchbook covers and rotate engine in driven direction by hand and make sure all marks on 4 cams and 1 crank line up.

    pin cams again with matchbook and torque cam cogs bolt. remove matchbook covers spin engine and check marks line up. you are done.
     
  5. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    Thanks for the information. I've read several threads from both of you guys in the archives and put a lot of faith in your advice. Your detailed description is exactly what I was looking for.

    I'm currently in the process of cleaning everything, due to the previous leaky cam seal, but will begin putting the cams in this week.

    I do have some additional questions:

    Is there an easier way to cleaning the cam cover gasket surface than my current method, Napa gasket remover and a Scotchbrite pad?

    Is there any risk to the new timing belt by using it to hold the cam pulley as I torque the bolt to 78 ft-lb?

    How far do you drive the cam seal into the block? I'm assuming all the way in until it bottoms out, but want to make sure.

    Again thanks.

    Donny
     
  6. fatbillybob

    fatbillybob F1 World Champ
    Consultant Owner

    Aug 10, 2002
    19,033
    socal
     
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  8. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    Verrell, I followed your instruction and have most everything bolted back up. Thanks for all of your help. I still have to install the cam covers (I've already trimmed the gasket around the o-ring) and refill the A/C sytem.

    I have a few questions before finishing up:

    1) As I rotate the engine the timing belt gets tight and loose (which corresponds to Verrell's instruction to tightening the tensioner when it as it's max extension). When it is the loosest (is that a word?) I can twist the timing belt not quite 90 deg, maybe 75-80. When it is at it's tightest, I can barely twist it at all, maybe 20 deg. Timing belt slippage is my biggest concern so I'm very paranoid about getting this right.

    2) On the installation of the cam cover gasket. I plan to use Permetex Copper RTV. VERY thin line along entire head/gasket surface with a thicker squirt at the o-ring. It seem's there are allot of ideas on this subject. I guess I'm wanting to make sure my method is acceptable.

    3) I've replaced most all rubber components, belts/hoses, but I'm having difficulty finding the following hoses: 7/8" w/cotton braid, 1/4" w/cotton braid, fuel 1-1/4" fuel tank connection hose, and the 2-1/8" filler hose. Any sources for these would be appreciated. My local parts supplier sold me Gates Green Strip for the tank connection hose but I didn't install it since it is a coolant hose and I don't know if it's compatable with gas.

    Thanks

    Donny
     
  9. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    Correction concerning the timing belt tension, I just looked at it again and I can turn the belt face about 45 deg at the tightest point.
     
  10. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,951
    Austin TX
    Full Name:
    Brian Crall
    "A" If you want to use Scotch brite on the cam covers thats ok, just clean the cover very well befor reinstallation. Don't use it on the heads, some will get into the motor, it is very abrasive and can do harm to the motor internals. Use (carefully) a gasket scraper. Do not use any gasket sealant on the entire gasket, Just use a good silicone sealant at the corners with special attention to the O ring area. I use Three Bond (a little hard to find) but Permatex ultra black is good to.
    "B" Be certain before you reinstall covers that with the flywheel mark at PM1-4 that all 4 cam marks line up exactly with the marks on the cam caps. Use a mirror and flashlight to confirm this on the 5/8 bank.
    "C" The generally accepted method to tension the belts is after all cams are timed tighten the belt strecher for one bank so that the belt is tight (precision not important at this point) loosen the other. Carefully turn the motor in the direction of travel and watch the belt strecher, it will move slightly in and out. When it gets to its outermost (tightest position) while still slowly turning motor tighten it, just enough to temporarily hold it in position. Now you can relax, get your torque wrench and torque it to spec. Repeat procedure for the other belt. When you are done with both, I, as a check slightly turn motor backwards to bring any slack that is remaining to the long portion of the belt. Wiggle it back and forth and twist it like a barber pole. It should not be tight like a guitar string nor should it be loose and floppy, a bit of judgement is required here but you should be able to twist it without a great deal of effort to between 45 and 90 degrees. If you can twist it 90, easily it is prob too loose.
     
  11. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,951
    Austin TX
    Full Name:
    Brian Crall
    Just reread your post. Gates green stripe is coolant hose and is NOT compatible with gas.
     
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  13. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    Thanks Brian. I can't twist it "easily" to 90 deg. even when the belt is at it's loosest, and can't get it to 90 deg with "lots" of effort when the belt is at it's tightest, only to about 45 deg. or so. By looest and tightest, I mean when I turn the motor and stop it on the belts tightest and loosest points. Does that sound about right?
     
  14. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    26,951
    Austin TX
    Full Name:
    Brian Crall
    Try like I said, Back the motor up a few degrees, then test. If it's closer to 45 than 90 it should be OK.
     
  15. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    I'd say you've got it about right. ie: Can twist past 45 degrees, but not all the way to 90 degrees in loosest position, & to about 45 degrees in tightest position.

    You've got a 2V right? The 2V engines seem to have a more distinct loose & tight belt position during rotation than the 4valve engines do.


    White stripe is Gates fuel rated line, green stripe is great for coolants, but it won't stand up to fuel or oil. For the larger connections, use Gates fuel filler line. It's properly rated.

    You may need to go to an auto parts place that primarily sells commercially to shops that service trucks as well as autos, rathar than a consumer auto parts store like AutoZone or PepBoys.

    RTV makes a gasket slipper than a greased pig. If you're going to use it, then use as little as possible. Smear it into place on the head, put the gasket down & press it into place, then wipe up any that squeezes into the inside. Less is better. When tightening things down, watch very carefully to make sure that the RTV doesn't squeeze the gasket ends slip away from the seal.

    BTW, Copper RTV's claim to fame is heat resistance. Super Black is rated highly oil resistant, so it would be a better match for this application.
     
  16. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    It's a 4 valve, but I've played around with it tonight after reading these posts and convinced myself it's where it's supposed to be.

    While vacuuming down the A/C system tonight I found it has a small leak, going from around 22 inHg to 12 in about 2 hours. It will stay at 12 and not leak to 0, but I'm assuming that's bad enough I might as well look for the problem now. I'm about to look through the archives for all the o-ring sizes, but if anyone has this info could you please post it? Also are all schrader valves a standard size? I hope to change them out tommorow and pull the system down one last time.

    Thanks for all the info.
     
  17. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    Also, if anyone is looking for hoses, I found a supplier in Florida that had everything I needed and seemed knowledgable about their product.

    Amazonhose.com

    Disclaimer**Wildcatfans not affiliated with Amazonhose**
     
  18. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    Shrader valves are std as far as I know. At least I've never encountered a non-std one or seen more than one in catalogs.

    Don't have the o-ring sizes here at work, but AutoZone has a nice A/C o-ring ass't that has 3 of most sizes, & 2 of the others. Has a ring size matching pix on the back of the package.

    If you're not in a rush, www.ACkits.com is another source:

    GM blue O-ring assortment kit 21-24657B ($7.52)
    Nylog O-ring sealant ($5.50) is worth investing in. It's 'hylomar' for A/C work. Can be used on fitting threads as well as O-rings.

    My only issue w/ACkits is they only ship UPS, so small items like these incur a high shipping overhead ($5 or so.).
     
  19. Wildcatfans

    Wildcatfans Karting

    Sep 4, 2001
    247
    Baton Rouge
    Full Name:
    Donny Bridges
    Well, last night I got it all back together and ready to start. I changed the fuel filter so I expected it to take some cranking time, but so far it hasn't fired up. I cranked until I began to smell gas so I pulled the plugs and stopped for the night. Today I reinstalled the plugs and tried again. It will initially sound as if it is starting, but won't. After that it doesn't sound like it wants to start. If I stop cranking and then start right back it again sounds as if wants to start but doesn't. I pulled the plugs to check compression, fearing the worst (timing jump), but got 145-150psi on all cylinders.

    Is there any way of determining whether it is firing when it should, like using a timing light on other cars? How long should it take to purge air from the fuel system? Is the bracket that holds the distributor cap the same for the front and rear bank (my label fell off before I reinstalled it)?

    Thanks for any ideas on where to start troubleshooting.
     
  20. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,283
    Texas
    Full Name:
    Steve Magnusson
    "like using a timing light on other cars" -- what, you think you've got something special? Of course, put a timing light on the coil wires during cranking to confirm/deny if the ignition system is working, and then go to the spark plug wires themselves to make sure the spark is getting thru the dist(s) OK.

    If spark and fuel seem present (yet it still won't fire up) another thing to check is to put the #1 piston in the firing position (i.e., rotate the engine by hand to put #1 at TDC after the intake valve has just closed), remove the appropriate distributor cap, and verify that the distributor rotor is generally pointing in the direction of the contact for the #1 spark plug wire.
     
  21. Mark 328

    Mark 328 Formula Junior

    Nov 6, 2003
    510
    Orange, Ca
    Full Name:
    Mark Foley
    While trouble shooting, keep in mind that you can see the rear exhaust cam timing marks thru the oil fill hole.
    And you can get a general idea of cam timing by looking at the index pointers on the fiberglass cam covers.

    BTW, my first item to check would be to swap the coil wires (front to rear) and try it again. If a cam moved the engine would probably sputter.

    Good Luck,

    Mark
     

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