Re: Won't run past 3500 rpm
 

On the small air cleaners, a friend had a new small air cleaner with the paper element. Swapped the paper one out for a 50s style screen type element & it ran great. Also was mentioned original dizzy. If its an 8BA stock dizzy, it doesn't work well with dual carbs.

Re: Won't run past 3500 rpm
 

UPDATE: It runs. I talked to a buddy that races a flathead at TROG and the like. He mentioned that his magneto had a tendency to burn the cores out of spark plugs and it'll act just like I described. I thought no way, but I was running a 60,000V coil, relatively high compression, and a large-ish plug gap. So what the heck, I threw a new set of plugs in it, put a stock coil back on, tightened up the gap and now it rips. The old plugs don't have continuity through them measured with a multimeter. I've never seen that before and would have NEVER guessed that was the issue. They look perfectly fine (not fouled, etc) but they're 100% bad...

Re: Won't run past 3500 rpm
 

Fantastic. Stock ford ignition systems for the most part are Great.

Re: Won't run past 3500 rpm
 

Awesome. Great news.

Re: Won't run past 3500 rpm
 

It's great that you found it. We used to have the same problem with 2 cycle snowmobile engines. All of a sudden, one cylinder would start running sour. We'd pull the plug, and when we looked at it, it seemed perfect. However, if we replaced it with a good plug, and it would run like gangbusters. A friend of mine had a spark plug cleaner and tried to resurrect several of these"dead" plugs; to my recollection, they just wouldn't come back.:confused: