Has Anyone Updated Ignition on a 105hp?

[tater76]

Hey folks, so I just aquired a 68 105hp Chrysler for cheap. I was just wondering if anyone has converted one to a newer style ignition system? Is it possible? I just don't like working with 44 year old electronic components. Oh.. and what size pistons are in it, (I dont have a manual that covers these older ones). Any input would be appreciated.

 

[Frank Acampora]

Re: Has Anyone Updated Ignition on a 105hp?

3.3125 bore X 2.80 stroke--same as the 120 and the later Chrysler 4 cylinder 90 and a couple of others. Old Chrysler racers used to retro-fit Mercury ignition systems.

You can upgrade to Prestolite ignition (and some Mercury) but you need all the components including the stator and stator mount. You must drill and tap the top of the block for five (5) 1/4 X 20 mounting bolts AND you must find or make a 1/16 thick spacer for the top of the bearing. (some 2 cylinder Force with Merc ignitions have this spacer). You must not drill too deep and penetrate the block into the crank chamber.

Personally, I think either ignition is good but the Prestolite is a little more accurate since it does not use a distributor. My 140 has the distributor Motorola and I trust it to take me anywhere--and back. I'm lazy! My modernization of Motorola ignition is limited to using an electronic distributor with the electric eye.

 

[tater76]

Re: Has Anyone Updated Ignition on a 105hp?

Thanks Frank, when I went to look at this one and popped the cowl to see that old red selinium thing and got nervous. As for the Prestolite conversion... sounds all too familiar I have done three so far in my Chrysler/Force journey. Its a fun swap, but only reasonable if you have the parts laying around. The only real hangup I found was that the stator mount has to be EXACTLY centered. My first conversion nearly ruined the flywheel magnets when everything heated up after a few minutes of running, and the stator began rubbing the magnets! Lesson learned, I built a jig and use locktight now.

So, whats the function of the red selinium block?? (I think thats what its called anyway) and someone put a car type coil on it? It runs fine, but is this the way to go?

 

[Yesterday]

Re: Has Anyone Updated Ignition on a 105hp?

The selenium thing, is a rectifier, easily swapped out with a $15.00 solid state bridge.