Timing gear replacement
Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models
All V7 / V700, all Ambassador, and all but the latest Eldorado loop frames came with three timing gears; one each for the oil pump, crankshaft, and camshaft. Even a few early V7 Sports came with timing gears. My camshaft timing gear broke just north of Bemidji, MN (but that's another story). In the process of replacing the gears, I have learned the following:
- The gears must be replaced as a complete set. Do not be tempted to just replace one gear.
- Not all gears are the same. I've seen the following configurations:
- Oil: 52 teeth; Crankshaft: 44 teeth; Camshaft: 88 teeth and 5 dowel pin holes; white paint marks. I believe this to be the standard configuration that was used in the V7 / V700 models.
- Oil: 29 teeth; Crankshaft: 25 teeth; Camshaft: 50 teeth and 6 dowel pin holes; red paint marks. I believe this to be the standard configuration that was used in the Ambassador and Eldorado models (1307-1700).
- Oil: 31 teeth; Crankshaft: 26 teeth; Camshaft: 52 teeth and 5 dowel pin holes; white paint marks. This is the configuration in my Ambassador. I'm not sure, but I think it was the standard configuration that was used in the V7 Sport (1407-1700). Even within this tooth count, there are differences between the gears. My original camshaft timing gear had smaller holes than my replacement timing gear (not the dowel pin holes, but the large holes bored simply to remove weight/add a little flex).
- If you are going to get a replacement set of timing gears, be sure to count the teeth on your existing gears and get a set that has the same number of teeth. If you don't, you will have to time your valves.
- Replacement is straightforward and pretty easy. Just follow these steps:
- Do not remove the engine. This procedure can easily be done with the engine still in the frame.
- Drain the engine oil. If you don't, it will run out the front of the timing gear cover.
- Remove the three bolts that secure the generator cover.
- Remove the three bolts that secure the pulley.
- Remove the big nut on the end of the crankshaft. The nut takes a 26 mm socket and is removed in the standard lefty-loosey direction. If you have an impact wrench, use it. If not, remove the starter and use a pry bar wedged in to the ring gear to prevent the crankshaft from turning. You might as well remove the starter, anyway, because you'll need to stick a bar in the ring gear to prevent the crank from turning when you torque the nut back on.
- Remove both the outer and inner pulley halves. Keep track of how many shims are placed between the two halves so that you don't have to figure it out again on installation. Remove the generator belt, too.
- Remove the front engine mounting bolt. You'll probably want to support the front of the engine a little bit with a jack...but even if you don't, the front of the engine won't sag very much at all.
- Remove all of the 6 mm bolts that secure the front of the timing case to the block. Again, if you have an impact wrench, use it.
- Remove the timing case cover. You may think it is necessary to remove the skid plates (oil sump guard plates) in order to remove the timing cover, but it is possible to gently tilt the cover away from the block and remove it.
- IMPORTANT: Before you remove any gears be sure that the following painted marks are present:
- The oil pump gear does not need any markings.
- The crankshaft gear should have a single painted mark on one tooth. This mark should engage between two painted teeth on the camshaft every two revolutions of the crankshaft. Verify that it does.
- The camshaft gear should have two painted markings. One mark should be on the inside set of dowel pin holes. The hole through which the dowel pin is currently located should be marked with paint. The other mark should be two gear teeth that meet with the mark on the crankshaft gear every two revolutions of the crankshaft (one revolution of the camshaft).
- IF THESE MARKS ARE NOT PRESENT, PUT THEM THERE!
- Remove the big nut on the end of the camshaft. The nut takes a 26 mm socket and is removed in the standard lefty-loosey direction. If you have an impact wrench, use it. If not, remove the starter and use a pry bar to prevent the camshaft from turning.
- Remove the nut on the end of the oil pump. The nut takes a 13 mm socket and is removed in the standard lefty-loosey direction. If you have an impact wrench, use it. If not, remove the starter and use a pry bar to prevent the camshaft from turning.
- Using a gear puller, remove all three gears. Mine came out very easily.
- Transfer the markings from the original gear set to the new gear set:
- The oil pump gear is the easiest, as no markings are required.
- The crankshaft timing gear is fairly simple. Just stack one on top of the other, align the key way, and carefully transfer the mark from one to the other. In my case, both crankshaft timing gears shared the same mark.
- The camshaft timing gear requires special attention. The workshop manual describes how to do this using a special tool. Since I didn't have the special tool, I used a piece of stiff non-corrugated cardboard, the dowel pin from the end of the camshaft, and a socket that fit quite nicely into the center whole of the camshaft. Using your original camshaft timing gear, carefully cut out holes for the center hole and dowel pin hole. Then, with the cardboard in place over the gear, carefully cut out the marked gears. Now that you have an accurate template of your existing camshaft timing gear, try each dowel pin hole on the new camshaft timing gear until you get precisely the correct alignment. Then, mark the dowel pin hole and the two teeth with paint.
Take your time doing this and get it right. If you don't, you will have to go back in and do it all over again.
When creating my template, since my camshaft timing gear was in four pieces, I used a length of electrical tape to hold the pieces in their original position.
Unlike the crankshaft timing gear marks, the original markings on my broken and my replacement camshaft timing gears were NOT the same...they were off by several teeth. So, don't simply trust that the markings are correct, make them so!
Although tedious, this procedure is far easier than re-timing the valves.
- Installation is the reverse, but be sure to do the following:
- Install a new timing cover seal (make sure to grease it before you install it).
- Install a new O-ring between the crankshaft and the crankshaft timing gear.
- When installing the timing gears, be certain that the number 2 cylinder (the one on the left) is at top dead center on the compression stroke (both valves closed). The keyway in the crankshaft will point toward the number 2 cylinder. The camshaft dowel should be at about 11 o'clock. Then, just be sure to line up the painted marks.
- Torque the crankshaft and camshaft nuts to 108 foot pounds. Torque the oil pump nut to 22 foot pounds. Insert a pry bar in the flywheel (through the hole left by the removed starter) to prevent things from turning.
- Install the pulley so that the left most mark is in line with the keyway on the crankshaft.