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need help with timing chain

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Bross82, Mar 11, 2002.

  1. Bross82

    Bross82 1/2 ton status

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    hey, i had a leak from my timing chain cover so i went to change it and first found it that the cover wouldnt go back on... i guess the oil pan has to come off too.... but then someone my friend knows happened to come by and saw my the condition of my timing chain and recommended changing it..

    i need help on what to do with changing it and what to be careful of when doing it.... also what would be a better timing chain to get for a 305? that guy recommended a dual chain but i'm not sure if its much better and who carries it... i need more help on installation than picking out a chain though, but both is great...

    thanks,
    matt
     
  2. Blazer79

    Blazer79 1/2 ton status

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    Go to www.summitracing.com and browse their online catalog. They have plenty of good stuff.

    You can get a cheap Summit brand chain or a more expensive, higher quality chain like Cloyes. Replacement is easy:

    1) Turn your engine until the damper is at the 0 deg mark.
    2) Remove the harmonic balancer (you'll need an extractor for this)
    3) remove timing cover. Verify that the dots on both sprockets are one above the other.
    4) Unbolt the cam sprocket, remove chain.
    5) You'll need another extractor to pull the crank sprocket.
    6) Installation is the reverse of these instructions, just make sure that the little dots on the sprockets align again.

    Hope this helps.
     
  3. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Just make sure the chain you use has STEEL gears and a good chain. $20-40 will buy you a very good one.

    If you like the supercharger, "whine" a gear drive may work out for you too. I think they're annoying, but some people think they're cool.
     
  4. txbluethunder

    txbluethunder 1/2 ton status

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    on that engine i believe you also have to lift the engine up a few inches and drop the oil pan to access the lower timing seal. go rent a cherry picker and take it slowly.
     
  5. bigmack

    bigmack 1/2 ton status

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    I would defenitely agree that you should replace the chain and gears. The upper timing gear on alot of 305's that I have seen is not a solid steel gear, and over time they are bad about stripping. My brother has a Monte Carlo SS that had a 305 originally & the timing chain gear stripped & completely screwed up a perfectly good motor. A good quality chain is great insurance for not alot of money.
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Whatever you do, do not get confused if you line up the dots and the distributor is not pointing at the # 1 wire. When the dots are lined up the engine is at TDC for the # 6 cylinder. The reason for lining up the dots while the engine is on the # 6 cyliner TDC is to make it easier for you to be sure the dots are actually lined up correctly. (easier to line something up when they are close together than far apart)
     
  7. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    been told they rob HP to. dont know if this is true or not
    Grant
    I STILL WANT A SET.
     
  8. chevyracing

    chevyracing 1/2 ton status

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    Gear drive is good. It doesn't rob any horsepower that you would even detect on a dyno.

    when you put the timing cover back on if you do not drop the oil pan you will have to trim the ears where the seal goes or it will not go back on. (timing cover) The inside lip needs to be cut back at a 45 degree angle, in other words grind about a quarter inch off of the inner lip on the corners.

    John
     
  9. Bross82

    Bross82 1/2 ton status

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    i was wondering, if when i go to take the chain off and the sprockets... will the cam or crankshaft move much or should they give enough resistance so that to dont move much or dont move at all?
    will the cam move when taking its bolts out?

    if the camshaft or crankshaft does move, can the sprocket just be put on and used to move it back?

    when putting the crankshaft sprocket back on, do i need anything to put it back on or can it just be pushed back on?

    when putting the harmonic balancer back on, does that need to be lined up any way or does it just bolt back on?

    thanks a lot,
    matt
     
  10. Blazer79

    Blazer79 1/2 ton status

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    I had those questions in my head when I did my chain too.

    1) Tthe valves push the rocker arms, those push the pushrods which push the lifters, which brake the cam. Some valves are open, some are closing, some are about to open. They all are pushing to each other, so they are kinda locked up. Short answer: No, it won't move easily.

    2) Better make sure it doesn't move, or you'll mess up your timing.

    3) It can be pushed back on. A little sanding on the surface and a little oil helps.

    4) It has an alignment tab, so it can only go in one direction. To install the harm. balancer back, you better get an installation tool. It can get pretty hard. I bent several washers trying to install it with a "bolt and washers" method. I ended up getting the appropiate tool. Just make sure you sand it and oil it thoroughly before installation.

    Hope this helps.
     
  11. txbartman

    txbartman 1/2 ton status

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    Like blazer said, there is enough resistance on both the crank and the cam shaft that they shouldn't turn when removing or installing the gears. Remember, the bolts are only at about 20-30 ft lbs. I would recommend replacing the gear bolts with grade 8s from home depot or something. The timing gear sets usually only come with basic grade 3 (i think) bolts. It's pretty darn easy to over-torque one of these and break the bolt off. Not a good thing. To avoid this, replace with grade 8s and torque them PRECISELY to the proper setting. The grade 8 gives more room for error (over-torqing) than grade 3. I also recommend using loc-tite on these bolts. You don't want them coming off.
     
  12. Bross82

    Bross82 1/2 ton status

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    hey, this should be the last questions:
    i noticed on the back of the box for the timing gear it showed to make sure the timing chain sprockets are lined up. does the crankshaft sprocket go in and lock in at a certain point and then just tighten the cam sprocket until they are lined up? i just wasnt sure how the cranksprocket stayed in lined up if it isnt held in somehow

    it says to lubricate the timing chain, should i just use normal motor oil or use something else and how should i apply it?

    also can the oil pan be removed on my 305 without lifting the engine? from what i've checked before, it seemed like i might be able to get at the last two nuts if i remove the starter and oil filter and use a wrench, i couldnt get a socket over it before. if i cant do this i'll prob just wait to change the oil pan gasket another time.

    thanks a lot,
    matt
     
  13. 77JimmyMan

    77JimmyMan Registered Member

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    Dude to get the front cover back on you dont need to remove the oil pan. All you got to do is cut the corners off on the inside lip on the bottom of the cover. This should give you enough room to push the cover down in the pan and then towards the block. Cut the little end tabs off the seal that would normally lock into the pan gasket and put some high temp silicone sealant at the corners. If you pull the front of the pan down and the just bolt it back up it most likely wont seal again properly and leak. If you go that route, you might as well just pull the whole pan off a buy a new pan gasket set. Some repair manuals go over this with pictures too (I personaly like the pictures).

    ~Mark~
     
  14. txbartman

    txbartman 1/2 ton status

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    I don't remember being much of an issue when installing my crank sprocket gear. I believe it is a press fit (trying to remember) that goes all the way on. When all the way on, it lines up. As long as the balancer is on, the crank gear won't move.

    You can use regular motor oil to lube it. But, that will drain off kinda quickly. If your engine may sit a bit (several days) before cranking it, go to the parts store and get some cam lube. This stuff is heavier and will not drain as quickly. If you go this route, be liberal with it and I recommend changing the oil after about 1000 miles to get any residue from that lube out.
     

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