grruminator78

Okay here's something that's been stumping me for a couple of month. I've tried everything I can think of but to no avail.
Okay two of my plugs (can't remember the numbers but they are the second from the back of both sides of the motor) are carbon fouled bad. The four up front usually get this white stuff all over them. I've tried leaning out the carb and nothing. and no matter how much I try to lean it out I still run rich (very gassy smelling exhaust). Any ideas?

Soaring

You may need to overhaul that carb. The numbers are 3 and 7.

scott_m_mil

It may have to do with a weak iginition, possibly a timing issue. The white ashy looking color may have to do with your valve seals. Check out this site for a little more detail on spark plug diagnosis.

http://www.centuryperformance.com/spark2.asp

Scott

grruminator78

yeah glen, I def need to rebuild that carb, thanks for the plug numbers. I'm currently trying the timing. I just don't want to put too much work on it before I rebuild it. Heck 8 plugs once a year is not bad. She's a happy horse when she get's the new plugs every year

wow that web page was awesome, I smell FAQ link

ZZmustang

What kind of intake manifold do you have.
Cylinders on opposite sides are doing the same thing make you wander about the runners in the intake
Take the carb off and remove that rag you left in there. Ha.

Lumbergh

Sounds to me like those two cylinders aren't firing consistently dumping unburnt fuel into the exhaust. That would explain two black plugs (sign of running rich in those two cylinders) and gas smell. I'd look at the plug wires, coil, and distributor cap and rotor. When I first got the Mustang I'm working on, the PO had installed an aftermarket exhaust. One of the plug wireboots was too close to the exhaust causing it to melt/burn, resulting in the plug wire discharging against the exhaust manifold part of the time.I thought it was running rich (and rough) due to needing a carb adjustment until I took a closer look at the plug wires.

grruminator78

plug wires are good, I'm running a stock exhaust manifold, and stock intake manifold. Coil isa little old, but cap and rotor are relatively new and when everything was brand new minus the coil same thing. and I already removed the rag

mustang141

Just a thought but ... the firing order on a early 289/302's is 1-5-4-2-6-3-7-8 and the firing order on a late model 302 HO's and 351's is 1-3-7-2-6-5-4-8.Notice the 3-7 order is the same on both.I'm sure you do butdo you have your plug wires on your distributer correctly. Like do you have the3 and 7 on backwards. The engine will still run and likely won't even backfire ... just not quite sound right and it will smell gasey and have those two cylinders foul the plugs. Also it will not have the power it should and it will stumble a bit when stepped on hard. Just sounds odd that it's those two cylinders which are together in the firing order. Anyway, just a thought.

grruminator78

I suppose I can check that again, but I'm sure the wires are correct.

grruminator78

The only thing is the front four are crazy too, and the back two are just fine. still, worth checking again. thanks for the idea.