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Ford Bronco Parts - Classic Vintage Early Bronco Parts

Timing Chain Replacement

Tech article by Mike Dodd (md_lucky_13)

     This tech article is intended as advice only, and should not be used in substitution of any correct manual, instructions, or specifications. There is potential for loss of property, injury, or even death if done incorrectly. If you are uncomfortable with the swap, it is best to have a certified mechanic work on your vehicle. Basically, I don't want to be responsible for anything that could go wrong while doing this swap: by using this information, you are doing so at your own risk, and agreeing that I cannot be held responsible for any damages, injuries, or other acts of god that may occur. 

The first step is to gather everything you will need:

  1. New timing chain
  2. Gaskets for water pump, timing chain cover, and front of oil pan (should be included with timing chain cover)
  3. Basic hand tools (wrenches, screwdrivers (good for prying old gaskets), pry bar, and rubber mallet. 
  4. Harmonic balancer puller
  5. Coolant
  6. Motor oil

     The second step is to set the motor at TDC (Top Dead Center). An easy way to do this is to remove a spark plug for cylinder #1, place a screw driver in it, and carefully bump the motor over (with the coil wire grounded) until the screwdriver just starts to fall back down. A turn of the harmonic balancer will return it to exact TDC. 

     The third step is to remove everything that may be in your way during the installation. It will take a lot more time trying to fight around things then to simply remove them, out of your way, the first time. This includes your fan, alternator, power steering, and any other brackets or systems that may be in the way. It is also a good idea to remove the radiator. It may be possible to install a new chain with the radiator still in place, but once again, it will take more time fighting with it then it would to simply remove it. Go ahead and do a coolant change at them time; its cheap and easy. 

     Once you have drained all the coolant from the radiator, and removed any objects that may intrude into the working space, it is time to remove the water pump. The water pump is held on by a series of 7 bolts 1/2 bolts. Once removed, you can move onto the harmonic balancer.

Early Bronco Timing Chain Replacement


     The harmonic balancer will take a special tool (called a harmonic balancer puller) to be removed. Before you attack the puller, makes sure you have loosened the large bolt holding it in place (in the center of the harmonic balancer). Once you are ready, place the puller in position, filling at least 3 holes with the correct size bolts. Sometimes a longer bolt will allow you more room to position it into place. Make sure that all bolts are the same length before pulling the blanacer.

Early Bronco Timing Chain Replacement


     After the harmonic balancer has been removed, you can remove the timing chain cover. There are only a few more bolts holding the cover in place. Make sure you get the bolts connected to the oil pan. 

     *NOTE: You are going to get coolant into your oil. No matter how careful you are; it will happen. Be prepared to change your oil after you do this swap. 

     At this time, you should be able to inspect your current timing chain. This timing chain had an unknown amount of miles on it, but it was definitely worn out. Notice the slack at free stand, and with tension:

Early Bronco Timing Chain Replacement    Early Bronco Timing Chain Replacement


     I then used a pry-bar to remove the old chain. Very carefully pry back and forth on the top sprocket. Keep the tension even on each side, and the chain will slowly work its way off the shaft. Keep sliding the chain in unison, top to bottom, until it is free to move with your hands. Once removed, it is a good idea to inspect your cam-block, check for play in the cam, and other basic maintenance items. 

Early Bronco Timing Chain Replacement    Early Bronco Timing Chain Replacement


     Before installing the new timing chain, I decided to paint everything a nice bright blue color again. I chose to remove my entire oil pan, in order to replace it with a new pan, and fix a leaking oil pan seal. You do not have to remove your entire pan, although now would be a good time to replace the gasket:

Early Bronco Timing Chain Replacement


     Once you have painted everything, it is time to install the new timing chain. I would recommend using a very liberal amount of assembly lube for this process. It will help the chain on initial startup, and makes sliding the chain into place a lot easier. Carefully position the chain in place with both marks lined on the sprockets. The mark on the top sprocket should line up directly with the mark on the bottom sprocket, with the top sprocket mark in the lowest position, and the bottom sprocket mark in its highest position. If they will not line up correctly, your cam may be out of line with the crank. In order to fix this, you will have to adjust the cam until the marks line up. My engine was already very close, so I did not have to move the cam in any direction. 

Early Bronco Timing Chain Replacement    Early Bronco Timing Chain Replacement


     Using the same principle as removing the old chain, carefully start tapping the new chain into place with the rubber mallet. Make sure you do not bind the chain, and be very careful to move the lower sprocket in sync with the upper sprocket. Once it will go no further, check that it has remained in line, and check tension. Obviously, this was a huge improvement over the previous chain:

Early Bronco Timing Chain Replacement


     Now it is time to install everything you removed. Only use new gaskets, although a small dab of gasket-maker around the water ports is a good idea. It is also a good idea to use a small dab of gasket-maker around the front seal of the oil pan, where the oil pan dips for the front seal.

     Return the harmonic balancer to position. Carefully tap it as far as it will go. Use a torque wrench to snug it back in place, following the manufacture's recommendations.

     Continue bolting the water-pump into place, and finally bolt all accessories back in their locations. Return the fan, radiator, and prepare to start. Don't forget to change the coolant and oil at this time. After you start, be sure to check and adjust timing to the correct manufacture's specifications.

Early Bronco Timing Chain Replacement    Early Bronco Timing Chain Replacement


Tech article by Mike Dodd (md_lucky_13)


 

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