Doll Posted September 8, 2005 Posted September 8, 2005 I spoke about a 14 Briggs a while back that had been partly changed to Magnitron ignition. I have yet to send off the flywheel but wanted the unit up and running (belongs to a friend and he needs it) So I changed the mag back to the old style and placed new points in it. As I said before, points set at .020 don't close. Never heard of such before but the only thing that added up was a worn cam.. Removed the cam last night and sure enough. A pretty good grove is worn where the plunger rides and the plunger its self is badly bent. It seems to me that the plunger may have been bent when someone was in the engine and the bend put the sharp edge of the plunger to running against the cam where it wore a groove. Has anyone ever run into such as this before ?
D-17_Dave Posted September 8, 2005 Posted September 8, 2005 Rarely do I see this type of problem on a small engine but I do see simular things like worn cam lobes in distributers and stuff. One alternative is an after market atom ignition modual. This will illiminate the points and convert it to electronic ign. without reqiuring the polarity on the flywheel to e reversed.
Doll Posted September 8, 2005 Author Posted September 8, 2005 Tried one and it did not work.. My understanding is that at least when they first came out they said for 14 hp and less. No idea if it didn't work because of being borderline or what.. Would have been nice if it had..
BLT Posted September 8, 2005 Posted September 8, 2005 I have a "Mega-Fire" unit on my 7010 for 15 years, never had a problem. The parts on my 10 HP Briggs are basically the same as your 14 HP except for piston and rings. On electronic trigger you you sometime have to reverse the wire hookups to make them work.
EDS Posted September 8, 2005 Posted September 8, 2005 I have a 14 Hp Briggs that does that also. I wanted the tractor to move snow and found that if I set the points to .002 they would close and I got a spark. I remember that some one said that there is supposed to be a phenolic rubbing block where the plunger rides on the cam. I assume it fell off but never opened the engine up to check. The plunger has to be changed from inside the engine.
johnmonkey Posted September 8, 2005 Posted September 8, 2005 I have a B&S 19d 7.25 hp and the points do not open very far. I am thinking that the plunger has worn (not a big shock after 42 years!!!!). My question is can I replace the plunger without dis-assembling the whole motor?? I tried the mega fire ignition module but had no luck. Do I read that reply correctly where all I had to do was reverse the wires? I have now changed the ignition to an external coil and it ran fine for a while, but now is intermitant again. It all points to the plunger (I think). JH
Simplicity314 Posted September 8, 2005 Posted September 8, 2005 If your machine has positive ground the wires must be reversed.
Doll Posted September 11, 2005 Author Posted September 11, 2005 I pulled this engine down and no suprise, The cam is shot. From what I can see, what happened is plain. This engine broke a rod and was rebuilt. No overbore etc. Just a slip shuck ring and rod replacement. Trouble is, they didn't replace the damaged cam shaft. They left some pretty large grooves and one of those crossed to the area that the points plunger rides. This explains both the reason why the plunger was bent, and why the cam wore down..
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