trying to figure out pertronx ignition upgrade

[tango13]

coil ohm question

Hey everyone,

Bought my '78 American almost a year ago and i'm just about ready to order parts for complete tune up (motor runs okay but everything appears to be original factory equipment and 25+ years is a little overdue IMHO)..

I'm going with a pertronix system as far as freshening up the ignition. Iv used their systems on multiple engines before and I'm sold on their products. Iv installed the ignitor kit on a mercruiser 228hp before and it was simple. This time on my merc 250hp, ill be doing the ignitor unit + the reccomended flame thrower coil. Motor is a '77 mercruiser "250hp" 350 w/stock points ignition

My questions is- which coil will I need, the 1.5 ohm or the 3 ohm? Correct my if i'm wrong but I believe the system already has an external resistor, correct? Ill admit, my electrical knowledge is weak, so I apologize in advance for my ignorance..

 

[thumpar]

If you go with the 1.5 you will still need to run a 12v line to the pertronix. The easy way is to use a 3.0 and run the same 12v to both. That is what I did on my last boat. Spend the little extra money on the Ignitor II. Then you don't have to worry about killing the unit if the key is left one.

 

[tango13]

If you go with the 1.5 you will still need to run a 12v line to the pertronix. The easy way is to use a 3.0 and run the same 12v to both. That is what I did on my last boat. Spend the little extra money on the Ignitor II. Then you don't have to worry about killing the unit if the key is left one.

Thanks for your input Thumpar. So basically, I can just bypass the external resistor and run a direct 12v to the coil +, and run the pertronix from the coil + (that has 12v direct power). correct? Is there any way to run an Ignitor/flamethrower combo without bypassing the existing resistor?

 

[thumpar]

People ha be tried to keep the resistor wire but many have had issues.

 

[tango13]

Hi everyone,

Heres another post about ignition upgrades. Basically I'm getting ready to do a complete tune up of my ignition system, and I'm trying to learn exactly what ill need before getting started. (FYI engine is a '77 Mercruiser "250hp" (350sbc)

I'm really confused about the points/coil stuff. This is what I think I have figured out so far. Coil is a mercury 32193 12v Externally resisted coil. and the mallory dizzy has a points setup. Now, what I would REALLY like to do is upgrade to electronic, preferably pertronix as I am very familiar with the product as I have used it in automotive applications and they work AWESOME...

This is where i get confused. I know the coil has an external resistor, and I have determined with the wiring diagram on the forum that my resistor wire is white (I have 2 wires going to coil+, 1 is white and the other is tan which goes to alternator). So, after a TON of reading on the forum and elsewhere, I have determined that the resistor wire provides around .8ohms of resistance and the coil has about .6 - .7 ohms of primary resistance. This would = around 1.5 ohms of resistance for the points ignition. Correct?

Now heres where it gets fun. I want to replace the coil.. and while doing so, I want to keep using the external resistor wire in the factory wiring (the white wire in my application). This would mean that if I were to replace the coil, it would have to be a low resistance coil (either a stock replacement, or a low primary aftermarket such as the MSD 8222 (.7ohm primary) or pertronix 5001 (.6 primary). Any of these low resistance coils would require that white resistance wire to get 1.5 ohms needed for at least the stock points setup, correct??

Now, throw in a pertronix unit. Would my stock resistor wire (white wire at coil+) be able to properly power the ignitor 1 unit? Since pertronix has the ignitor 1 as a direct replacement for points, I feel like it should work fine since the stock points works with the same voltage. A while back, my uncle installed an ignitor 1 unit on his 79' merc 228 with the exact same stock ignition setup and it worked fine. Technically, if I changed my coil over to the .6ohm pertronix, it would still equal the stock 1.5 ohms of resistance that the coil/points needed.

So, to sum all this up. I want to upgrade to pertronix but keep the stock wiring (I really dont like modifying factory wiring when I don't need to).

Can anyone help me with this stuff?

 

[Bondo]

and I'm trying to learn exactly what ill need before getting started. (FYI engine is a '77 Mercruiser "250hp" (350sbc)

I'm really confused about the points/coil stuff. This is what I think I have figured out so far. Coil is a mercury 32193 12v Externally resisted coil. and the mallory dizzy has a points setup. Now, what I would REALLY like to do is upgrade to electronic,

Ayuh,..... I suggest ya look into the Delco Voyager marine electronic ignition "Kit",.....

Current production, reasonably cheap, reliable, 'n Easy,.....