Ok, I bought a fairly nice old Bayliner Mutiny boat with the engine in several boxes.  The story was that the engine went out for rebuild but the mechanic went belly-up and left all the parts in the abandoned shop. The owner got most of dismantled parts back, but I noticed a few missing. 4 pistons - check, crank -  check, head -  check, cooling system - check, exhaust maifold and cooling system - check, timing belt and drive gears - ???. I had assembled and rebuilt right up to the front of engine and knew there was parts missing. With some research I confirmed that this engine is basically a Volvo B21 car engine that has uppy sized crank and crank bearings. The B21 is found everywhere in the auto scrap yards and I found all sprockets and belts easily....even bought a whole running engine which I threw in boat for awhile until real marine engine was ready. Yes the car engine  it blew up after a few months working as a marine engine but I did get all the external components that I needed. The other oddity with the marine version is a small rubber coupler that drives the raw water pump off the mid shaft.

It looks like this and was also missing, but with some good schematics online like HERE.  I was able to figure out where it all goes. A good friend and Gunsmith, Del Selin, actually made the couplers drive socket on his lathe that bolts to the cam that drives the rotor, oil pump and this water pump coupler. But the real purpose of this blog is tho compile solutions....sorry I drifted off subject there... Schematic of that drive shaft is HERE
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The dilema when putting this overhead cam engine together was to get all the timing right for valves, ignition and crank positioning. This list may help to replace belt or set timing:

STEP  1 Use a 24mm socket on the crankshaft bolt, to turn the engine to top dead center. The white dot on the cam gear will point to the mark on the cambelt cover at 12 o'clock. 
STEP 2  Place a screwdriver between the teeth of the flywheel and the bellhousing, to lock the flywheel and the crankshaft.
STEP 3 Loosen the nut on the belt tensioner and pull on the old belt to compress  the spring while inserting a nail into the hole of the shaft to take the  pressure off the belt.  
STEP 4 Ensure that all gears are set to their marks. Cam gear to 12   o'clock.
Intermediate gear to 3 o'clock. Crank gear to 12  o'clock. You should be able to draw an imaginary line from top marks through bottom crank marks. 
STEP 5 Start installing belt from crank gear and work your way
upwards. Keep tight in all areas with any slack in section of belt tightener mechanism.
STEP 6 Disconnect coil wire and turn engine over using only the starter motor 2 times. loosen the  tensioner nut 1 turn
STEP 7 Re-tighten the nut to normal settings and reconnect the coil   wire.
STEP 8 Start engine and warm up for 5 minutes. Repeat re-tenstioning belt  again.

This SOHC engine is supposed to be non-interference. I hope this blog can help someone out.
 

Cam gear bolt required torque setting.
37lbf-ft or 50 Nm.
Iintermediate gear bolt required torque setting.
37lbf-ft or 50 Nm.
Crank pulley bolt required torque setting.
44lbf-ft or 60 Nm and turn it an extra 60 degrees.

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