I definitely need one. I gapped the plugs down to .020 and the idle surged and was rough. I took it for a spin and I still get misfiring around 5000 rpm and up. I pulled the plugs and they were wet with fuel. I swapped wires, coil, tfi, plugs, cap and rotor. The only thing that made a difference was a DUI Screamin Demon coil. It raised the misfiring from 3500 to 5000. That tells me that I have weak spark for boost. This turbo spools lightning fast and I've hit 12lbs at 4400 rpm. I don't think the coil can keep up.Are you sure you need one? In general they aren't needed. I don't use one, i just gap my plugs down.
It seems that everyone can get away with the factory ignition except me. I have one cap and rotor from Rockauto and another new cap and rotor from Autozone. Neither one makes a difference. I tried a tfi and coil from Oreillys. No dice. I tried 3 different sets of wires. 4 sets of plugs at various gaps. Here's the rub...On the dyno I ran 14psl, no problems. It's fully spooled by 3500 on the dyno, .023 gap, ngk plugs, taylor 10mm wires, accel coil, older msd cap standard motor products rotor. What cap and rotor are you using? The new MSD stuff is very often problematic.
Msd 6al or 6al2 are probably ther most commonly used cdi boxes but i try not to recommend anything from "My Spark Dissapeared", their quality has gone down hill.
I run NGK 2756 BKR6E-11. My car makes 566 with 12lbs of boost. Stock bottom end, 11r heads. DUI live wires, Screaming demon coil and .28 gap. As stated earlier I was using the street box but I needed a 2 step and i run the 6AL2 now with no problems.I haven't dyno'd yet. I'm still fine tuning but the spark has put the brakes on that. I tried Autolite 3923's twice.
I also ran the BKR6E-11 plugs @.028. No dice. I went back to the 3923's but the strap showed the plugs were too hot. I'm currently using the Screamin Demon coil.I run NGK 2756 BKR6E-11. My car makes 566 with 12lbs of boost. Stock bottom end, 11r heads. DUI live wires, Screaming demon coil and .28 gap. As stated earlier I was using the street box but I needed a 2 step and i run the 6AL2 now with no problems.
i thought more fuel typically means it's easier to blow out spark because the resistance in the cylinder is higher making it harder to jump the strap, less fuel is easier to ignite but maybe I'm wrong. I use BRK7E which is the vpower version. I could probably get away with 6s though. I doubt it's the plugs. I don't have any experience with that cdi but i have a hard time believing it can do multiple spark all the way to redline.Plugs are NGK BKR7ES-11. Wires are DUI Livewires.
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I might agree but we aren't talking a large fueling difference. I went from 10.80 to 11.5.i thought more fuel typically means it's easier to blow out spark because the resistance in the cylinder is higher making it harder to jump the strap, less fuel is easier to ignite but maybe I'm wrong. I use BRK7E which is the vpower version. I could probably get away with 6s though. I doubt it's the plugs. I don't have any experience with that cdi but i have a hard time believing it can do multiple spark all the way to redline.
My point was less fuel shouldn't cause more ignition blow out/break up. I think you have something else going on. I'll have to think about it but i would probably do a voltage drop test to see if there are any ground issues.I might agree but we aren't talking a large fueling difference. I went from 10.80 to 11.5.
I see now. I suspect that leaning the mixture provided more power. It was very obvious when I repeatedly nailed it rolling in second gear. The rear was skating unlike when it was richer. It's hard to break drag radials loose on the hot pavement here unless you do a clutch dump at my power level. Today was 102° so you can imagine the blacktop temp. Would you agree that more power equals higher cylinder pressure?My point was less fuel shouldn't cause more ignition blow out/break up. I think you have something else going on. I'll have to think about it but i would probably do a voltage drop test to see if there are any ground issues.
All of my large grounds are new.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.