Misfire thoughts? 351 in the Shepherd project

I did verify the firing order as 18456273, as written on the engine which is normal for a RH 351 unless I'm mistaken. Starting at #1 and going CCW around the distributor cap. 

One problem I have is that I can't turn the engine by hand the correct way. I put a big socket on the bolt inside the main pulley but if I turn it CCW it loosens the bolt. I turned it CW so when I felt compression with my thumb over the #1 plug hole I figured that would be the WRONG TDC (exhaust stroke) so I turned it to the next TDC and that is where Art had plug #1 lined up with the rotor on the cap from the beginning. I hope I'm explaining that adequately. 

The engine does not have a tag, here are some pics though. 

#1 plug on your engine is the front cylinder in the most forward bank.  Look down on the front of the engine, one head is about 1" forward of the other.   This forward bank is always where #1 is located.

As you turn the engine over to find the compression stroke place your thumb over the #1 plug hole, you will feel air start pushing out when it hits the compression stroke, now look at the balancer and turn a little more till the timing mark lines up at TDC.  Verify the position of your rotor in the dist cap and you now have #1 location verified and can wire it from that  point, counter clockwise around the cap.

How was the engine stored from when it last ran?  If the carb was open to air you may have taken moisture inside the engine from the air.  That can cause rust inside and some things like valves can stick with rust in there.

How Old is the fuel you are trying to burn?  If it is over 1 year old you should swap for fresh gas.  6 mos old gas is pushing it today.   

Thank you for this. I did get the #1 TDC correct as it turns out, but the correct firing order is 18736245 for this engine. That's how it's wired now and it runs perfectly. 

I am running the engine on fuel from an outboard tank that's very fresh, the old tank is clean and empty but not installed yet. I did have a rag in the carb over the winter, where it was stored, so I think it's all good. 

Check out the video(s) from my other post to see how well it runs now! 

Thank you again. 

Tim, Mark, Ken - thank you again, and Ken your analysis is dead on. 

For 8 years I worked at the marina where this boat is kept and while I have never been to any tech school, I listened to the techs all the time and learned a lot from them. One of the most important lessons I learned was to gather a lot of information before throwing parts at something. I went to the boat a couple nights ago with the intention of gathering enough information to talk to you folks, knowing what you'd be asking (e.g. "did you find TDC on #1"). I took a notepad and took careful notes about what was happening and when. I knew whatever was wrong had to be relatively simple. Art found strong compression on all cylinders and I knew that. So it narrowed my diagnostics down to ignition. 

I now vaguely recall some conversations with Art last year wherein he might have referenced a 302, but in the time that has passed, I can't remember where we ended up on that, other than him shipping a running engine to me that looked a lot like every 351 I've seen in these boats over the years, wired for a 351 order for some reason. A 302 is just as good for this purpose and so long as it runs well, we're thrilled. 

For sure I will document the proper firing order on this, but as far as the "next guy" well, that's likely to be me in all honesty. This boat will almost certainly become mine eventually. I haven't really told the story here but it's the reason I met my wife. 

Indeed, we are close to cruising time. If I can have it done by early July (which is actually realistic, finally) he can take it to church which is what he was doing one day when he brought his daughter along... who is now my wife. So I hope that comes together for him. 

Indeed, this is all that matters in the end. I'm a happy camper and my father-in-law will be too. The engine was a reasonable price in a world where they just aren't that easy to come by, and it is going to be an excellent replacement for the old one, scrapping originality anyway (sorry Pete).