I have seen several posts about engine rotation because that is probably the single most confusing subject in all of boat repair running a close second behind is AC/DC wiring, is the black wire hot or is it a ground. Any of us who fool with boat engines either figures it out or gives up and gets drunk. It is a true brain twister no pun intended.
Try it simplify the mystery by ignoring the prop rotation or transmission rotation direction. Also forget how the engine is mounted in the boat.
Focus on just the engine itself. Post 1950 V8 marine engines are derived from the auto industry. Pretend you are sitting in a'66 chevelle looking out the windshield. The engine is obviously in front of you. The flywheel is at the back or rear of the engine and the harmonic balancer is at the front up by the radiator. When this engine is running it turns counter clockwise(CCW) looking at the flywheel from the drivers seat. Pretend there is a piece of glass in the firewall between you and the engine and you can sit there and watch the engine run. The flywheel will be turning CCW or to the left. TO THE LEFT. This is also called "standard" rotation. This is not reverse rotation!
As far as I know there has never been a clockwise (CW) rotating V8 in a car or truck. Please correct me if I am wrong!
Now get out of your Chevelle and walk to the front and raise the hood. Look at the harmonic balancer. Lo and behold it is turning to the right or CW. The flywheel, crankshaft and harmonic balancer are all turning in the SAME direction, but you are now viewing it from a different direction. The auto engineers referenced engine rotation as if they were sitting in the car looking at the back of the engine! Some folks get confused because when the are viewing a running engine from the front, such as when setting the timing with a light, they see that balancer turning right or CW they think the engine is a right rotation engine. It is not.
STANDARD ROTATION=COUNTERCLOCKWISE=CCW=LEFT HAND
Firing order 18436572
Now enter the boat builders. In an effort to make a prop spin clockwise they decided to design an engine that could turn clockwise or to the right. On a twin engine boat we all know 2 props spinning opposite will benefit performance. I don't know why they cared in a single engine application, but they have installed both left and right rotation engines in single engine applications. I think it had something to do with offseting the torque effects of a full throttle launch but I don't know. Anybody?
Everyone loves small block chevy (SBC). SBC's have been configured as 265, 283,302,305,307,327,350,and 400 cubic inch variations. And a popular custom variation, the 383.
Install a starter motor on it to make it turn clockwise, of course when viewing the flywheel, change the rear main oil seal because until somewhat recently they only were direction specific. Will it run? Not yet. So far the block, crankshaft, rods and pistons are unchanged. The heads and valvetrain are unchanged. The camshaft and firing order is what gets changed. The firing order simply gets reversed. 18436572 now has to be 12756348. It is the same crank but it now turns CW. The cylinders now fire in a reverse sequence. How do you change firing order? At the distributor by reversing the plug wires. Leave number 1 alone and change the others.
The camshaft is where it gets confusing, because a standard engine will use timing chain setup, i.e. small gear on the crank, a gear exactly twice as large on the cam and a chain connecting them. The cam turns half as fast as the crank in case you didn't know. The cam also turns the same direction as the crank in this scenario. That is a problem in a reverse rotation engine because they need to keep the cam turning CCW so it does not alter distributor and oil pump direction. They solved that problem by eliminating the chain and using 2 gears which mesh together. So now the crank can turn CW and the cam will turn CCW. The distributor and oil pump still turn in the same direction. What is different? The valve timing has to match the firing order therefore the cam lobes are ground to match the firing order. Valve lift, duration, and overlap are the same.
I am no expert on the Chris Craft Q series, but the company threw a huge curve at us with those puppies. We call em queer because they are. They basically attached the flywheel to the wrong end of the engine just to make people crazy. Find the original distributor mounting hole in the block. THAT is the rear of the engine. Not the end where the flywheel is. Careful because Ford engines have the distributor on the front of the block. All the Q series are Chevy's, I think. Remember also that Chevy did not change their engine, Chris Craft modified it to their liking.
Also some applications of SBC 350 reverse marine engines have the pistons mounted backwards on the rods with the notch facing the back of the block, because the wrist pins are offset. Same pistons, just installed backwards.
Be careful about trusting an auto engine machine shop with a reverse rotation assembly. A lot of them don't get it, been there done that lol.
Bottom line, locate the rear of the engine, bump the starter, view crankshaft rotation
CCW=left=standard
CW=right=reverse
Sorry for the long post, Hope this helps, experience says it won't