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check your coil primary voltage AND all of it's connections

grounds are a big problem too on spark-ignition engines. I found a TON of problems, by simply putting a ground strap between the cylinder head and the frame. Mind you this engine is mounted on mid/front plates so it "shouldn't" need a dedicated ground. But it liked it. Cheap to try.

I have an ignitionmate that I got when I worked at a yamaha dealer and it shows secondary voltage among many other things. Sec voltage went from around 15kv, after the ground it was closer to 33kv. Huge difference. Car got more consistent and much more responsive to fuel tune changes (100% methanol). Later on I tickled it with some nitromethane, which also required a lot more fuel. It was an experiment. If the ignition could fire it, I was going to play around with it. 46 degrees timing and put about 40% more fuel to it. It ate it up. MSD 6AL box, billet MSD 351w distributor and a set of taylor wires. Nothing special. The ignition box and distrubutor are like 30 years old. As a matter of fact I think they are 30 years old. I'd have to pull the box and look at the tag on back but I don't recall buying a box since I put this one in when I was a teenager. Bought it from Super Shops when they were still around.

if a street car, don't mess with this--but going to a 16v battery will help. Well I guess you could use 16v on the street too but you also have to adjust the alternator (replace the reg, or just put a whole new alternator on that is useful with 16v. It will charge at around 19v so you'll have to also address that. Some sensitive stuff won't take it. MSD box will, I am and have been for the last couple years, been on 16v but no alternator. Charge between rounds. Sec spark voltage went up a good bit when I went to 16v, about 1600v as I remember. The only change was battery and charger.

We also run Brisk racing spark plugs and have been happy with them. They last longer when playing with the fuel and the engine seems to fire off quicker (we start/idle on gas), seems to run a little smoother too. The Autolites went to crap when they started outsourcing them. I never (ever) had any issues out of the AR3933's for decades. Couple years ago the plug design changed slightly and I've never had any luck with them. The last time I tried to run them I had two (of 8) plugs arcing inside of the plug. The plugs themselves would light up, looked like LED christmas lights inside the porcelain. That and many other issues, I quit using them.

lastly a really rich mixture can sometimes fool the wideband into thinking it's lean. Ran into this on my old 74 Maverick/turbo 302 (carb/blowthrough). WBO2 says 11.5 but it runs like absolute poo with any load on it, wet plugs, I fought it for months. Finally dropped the jetting way back and the WBO2 says it was getting richer with smaller jetting. Kept going until it was where I wanted it, and it ran fine from there. Ran 14-20 psi depending on what I was doing with the car, with a bone stock 1976 Ford Maverick distributor (modified for boost) and a stock Ford coil and a stock Ford duraspark box on the fender. It did good.
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