Pertronix Ignitor vs Ignitor II and Coil, Mercruiser 470

[petrowski53]

Hey Guys,

My father just recently bought a new (to him) boat. It's a 1985 Thompson 185, with a Mercuriser 470 and Alpha One. He bought it from the original owner, who kept the boat inside his garage since new. The boat has seen minimal to no use over the past 20 years, so it is in pristine cosmetic condition. However, because the boat has sat indoors for so long, it does have several mechanical issues that need to be addressed before it is seaworthy again.

First and foremost, the boat will need a complete service. This basically means all new hoses (fuel and coolant), completely flush coolant, water pump kit, bellows, plugs, wires, and fuel system overhaul. I went though and rebuilt the Carburetor for him this weekend. The fuel pump diaphram was shot, so a new replacement pump has been ordered. The engine turns over fine and has (weak) spark.

While getting ready to tackle the ignition system, my father mentioned he'd like to convert to electronic ignition. I had considered it on my boat a few years back ('87 Thomson with the Mercruiser 2.5L), but never got around to it. I know there are basically two options. Either the Pertronix Ignitor (1146a) or Ignitor II (91146a) . There is only about a $30 difference in price, what are the advantages or cons of either? Also, can the ignitor II be used with the stock coil? I know the resistor wire usually must be replaced with a full 12v Source. I've just read a lot of conflicting information regarding the use of stock coils, especially the Ignitor II requiring the Flamethrower II coil (with the .6ohm resistance value).

Thanks guys. I'm sure this has been discussed before, but I'd like to get some more recent input on how these things are workin' out in your applications, especially if you have a 470.

 

[thumpar]

A big difference is that the Ignitor II has protection built in so that if you leave the key on without the engine running it won't ruin the module. On the original it can be a problem. They both will work with the same coils. The module will need a full 12v. When I did mine I put in the Ignitor II and Flamethrower II at the same time to make install easier but that is the only reason.

 

[stonyloam]

Go with the igniter II for the above reasons, but I would recommend the Flamethrower II coil, it is designed to work with the igniter II. Bypass the resistor wire and feed 12v directly to the coil and module. Be careful with the new fuel pump. Modern aftermarket pumps can produce too much pressure in a 470 because the geometry of the pump arm. Once you get the fuel system set up borrow a fuel pressure test kit from Autozone to check it. Should be around 3-5 psi. If too high you can add a spacer to the fuel pump gasket to set it a bit farther out, should solve the problem. While you are doing all of this stuff you should consider replacing the waterpump cam seals while you have the coolant out of it. If you don’t, chances are they will start leaking once you get it running. You may or may not need to sleeve the end of the cam, depending on if it is grooved or not. Do a search here for “replacing 470 cam seals”. Good luck! Welcome to the 470 Club

 

[petrowski53]

Go with the igniter II for the above reasons, but I would recommend the Flamethrower II coil, it is designed to work with the igniter II. Bypass the resistor wire and feed 12v directly to the coil and module. Be careful with the new fuel pump. Modern aftermarket pumps can produce too much pressure in a 470 because the geometry of the pump arm. Once you get the fuel system set up borrow a fuel pressure test kit from Autozone to check it. Should be around 3-5 psi. If too high you can add a spacer to the fuel pump gasket to set it a bit farther out, should solve the problem. While you are doing all of this stuff you should consider replacing the waterpump cam seals while you have the coolant out of it. If you don’t, chances are they will start leaking once you get it running. You may or may not need to sleeve the end of the cam, depending on if it is grooved or not. Do a search here for “replacing 470 cam seals”. Good luck! Welcome to the 470 Club

Thanks for the info! I'll recommend the cam seals, a lot of the gaskets are bad due to age, so I'd assume those are either bad too, or on the way out. I've read a lot about the overpressure of the replacement pumps. I bought a carter replacement after a lot of research, but i know it only came with one (thin) gasket. Do you have the part number for the correct thick spacer? Marine engine .com diagrams show 3 different part numbers for pump gaskets on my engine, so I wasn't sure which one is correct. (engine serial number is 6845959)

Thanks for all the info. I knew nothing about 470's when he bought the boat a few weeks ago, and I've certainly learned a lot. It seems these engines get kind of a bad rap, but with proper maintenance, are excellent performers with massive torque and decent economy.

 

[stonyloam]

I did see a spacer in some thread once, but have no idea what the number is. Best bet might be to check the pressure, and if it is too high maybe doubling up the gasket might work.

 

[Benny67]

I replaced both fuel pumps in my evil twin 470's just last season. Look at the length of the arm on the pump and you should see that they have 2 different lenths. the stock mercuiser one had a long arm with a thick gasket on it. The after market Carter’s had a shorter arm. I just used the gasket that came with the Carter it and it works fine.


Also, I did the pertronix myself. I just make it a point to make sure the key is off when the engine isn't running.

I used the matched set flamethrower coil as well. Both start much easier than the points.

Either one is probably just fine.