Pertronix Ignitor/Coil Setup

If everything is set up properly and you are really at 30 degrees BTDC on the ignition timing as "base" then your engine would have serious detonation issues under load.  Add 24 degrees of distributor advance at 3,000 RPM and you are looking at 54 degrees total advance.  Doesn't pass the smell test...

Try this:  Remove plugs (it makes it easier).  Using a large socket and ratchet or breaker-bar, rotate the engine by turning the large nut on the harmonic balancer.  Assuming your engine is RR, you will turn counter-clockwise when doing this from the front of the engine.  While slowly rotating the engine, place your thumb over the #1 cylinder spark plug hole.  On a small-block Ford, that would be the cylinder closest to the driver's seat.  While rotating then engine, you will eventually feel air pressure building under your thumb as the piston moves upward on the compression stroke.  Once you are sure that you are on the compression stroke (not exhaust stroke), take a long stiff soda straw or new pencil (eraser side down) and slide it into the spark plug hole until it rests on top of the piston.  Then, slowly rotate the engine while keeping you soda straw / pencil against the head of the piston.  As you rotate the engine, the piston will push the straw / pencil upwards out of the spark plug hole.  When the straw / pencil stops moving upwards, you should be at top dead center (TDC).  Then you can check your timing marks and indicator on the harmonic balancer and see if everything looks kosher.

Geez KENO, my backyard hackery pencil-in-the-plug-hole works great!  Last time I used that method was on my 1994…and there was enough space even with the manifold.  This is a good test to confirm harmonic balancer timing marks and timing indicator / pointer.  

I did that test this morning before I took the boat out and ran into the issues that ken described. It seemed right, but I wouldn't trust myself to feel a few degrees of difference so I was hoping to come up with a different way of doing it. I know the mech advance works, but I wasn't paying attention to what rpm it was advancing at so I can check that again when I get it running. The boat ended up dying today and wouldn't even idle. We got nice and wet getting it off the lake, so I need to get this fixed before the wife puts in a sell order.

I put the rebuild kit in my 4160 last night, don't think it was needed though. Carb was clean and the gaskets were still pretty pliable. However, I did find that the transfer slots on the primaries were almost fully exposed, which is probably why my idle mixture screws didn't do anything. The idle speed screw had to be opened that far to get the motor to idle at 700-800 rpm in neutral, so I'm not sure what's causing that yet. I adjusted the secondaries to the bottom of the transfer slots while I had it off as well.

After that, I attempted to reset the timing to around 10deg, but the motor isn't running at this point so it was a little tricky. It will occasionally hit while it cranks, but it's inconsistent and won't idle. Giving it a shot of fuel from the accelerator pump seems to help, but choking it doesn't. Won't start with the throttle fully closed or cracked open either.

If I can get it running, I'll check the timing advance. Last time it was running it had a random hard miss at idle when set to 10deg that would smooth out when I advanced to to that 30deg range. I'll also try to do a better job verifying that the timing marks on the pulley correspond to the true TDC soon. Thanks for all the input guys

Thanks, I'll check the air bleeds and make sure they are clear. Never heard of the whole ethanol/zinc thing before, that's interesting. The boat has only seen rec 90 since I've had it, but I imagine the previous owners probably used e10

I think that right about now a quick review of the status of the timing and carburetor might be a good thing.

The low vacuum thing has been bothering me so I checked the timing chain tonight by rotating the crank while watching the distributor rotor. It showed about 15 degrees of crank rotation before the rotor moved, so I went ahead and pulled the timing cover off and confirmed that the timing set is shot. Ordered parts and am hoping to have it back together this weekend. Can't really say this explains the weird ignition timing behavior, but it should be a step in the right direction.

Yes, it had the nylon coated cam sprocket, looked like everything was still intact though. The ignition timing references the crank so I wouldn't think the chain slop would require ignition advance. I do think (hope anyway) that the late valve timing was causing the poor vacuum, which is why I started investigating it in the first place. If I can get it to run and idle after this is fixed I'll take another look at the ignition timing to see how it behaves.

It doesn't really matter how much you turn the distributor in relation to the camshaft because you don't reference any timing marks on the cam though. In your example, the timing changes by 20 degrees at the crank no matter how advanced or retarded your cam timing is. It's no different than people who run adjustable cam gears aside from the fact that the timing might walk back and forth a little due to the play in the chain.

I'll see how it looks when I get the new timing set in there. Whatever the case may be, I appreciate all your help and the info you provide on here

Installed the new timing set, but that wasn't the problem. Changing it out did advance my valve timing a ton though, so I'm interested to see how it does next time I'm on the water.

After the timing set didn't fix it, I went back to the ignition system, knowing that I had compression and being pretty confident that I had fuel. I knew I had spark from using the timing light and an inline spark tester, but I didn't know how strong it was. So, I bought an adjustable spark gap tester and sure enough, it was bad. Must have been just enough to trigger the timing light and inline test light. I checked the spark again right off the coil and it was jumping 1/2" gap with no issues, so I took a really close look at the distributor cap and found some carbon tracking between posts.

When I installed the new cap this evening, it drastically changed the spark timing. I'm not entirely sure what was happening, but I'm guessing that the spark crossing over between posts in the cap was throwing my timing light way off and causing all the weirdness before. After putting it back at 10deg initial timing again, it fired right up and ran great in the driveway.

Isnt it awesome to fix things!  Good work.

Boat ran well on the lake with no drama today. I adjusted the accelerator pump linkage and it's running the best it ever has with no hesitation or misfires. Still only getting about 37mph @4200rpm out of it, but I that may be due in part to my exhaust.

I checked the timing in the driveway before I left and it looked to be advancing another 20deg or so when I revved it up. The pertronix unit is back in the distributor now, it must have been a coincidence that the failing cap got a second wind when I reinstalled the points.

I'm pretty happy with how it's running right now so I'll probably leave it alone and start fixing the little things until I'm done with it for the season. Appreciate all the suggestions and troubleshooting help from you guys by the way, there's a lot of knowledge on these boats floating around this site

It's a brand new Acme 540 and that reading is from GPS. On that note, if anyone knows where to get replacement gauge faces for the airguides, I would love to replace them. They are the off white style, which I think it a really classy look.