Morning folks.

Well, I spent a weekend replacing my valve seals on my 88 350 with 153K miles on it, since the number 7 plug would foul out with ash deposits about every 500 miles or so. I would pull the plug, and find the electrodes clogged with a light grey ash, preventing the cylinder from firing. (and making the car somewhat less than pleasant to drive......) Thinking that this was due to oil coming down the valve guides, I replaced the o-rings, and installed new, umbrella type seals on all valves. I used a leakdown tester to hold the valves in place while changing the seals, and found most of the cylinders to be in good condition. (although, number 3 had about 24% leakdown, and several of my exhaust valves leak....)

I could not beleive how well the car ran after I was done. (also put in new plugs, the ones that were in there only had about 5K on them) But, (and you knew this was coming....) after about 750 miles, the number 7 cylinder is again fouling out. Same old thing, light grey ash deposits clogging the electrodes.

Leakdown on number 7 was approx. 15%. So, I am inclined to beleive the rings are still good here. Am I missing something? Is the light grey ash from burning coolant, and not oil? The engine is still mostly stock. I have an MSD 6A smartbox, new cap, rotor, wires, plugs, and a blaster 2 coil. The rest of the engine is completely stock.

I am open to suggestions.......

Thanks

 

TTT, hey folks, I could really use some input here.... Please??

 

My # eight did that. My problem was a dirty injector spraying wrong. It washed down the walls of the cylinder. I had my injectors cleaned and haven't had a problem since.

 

Ok, that seems reasonable. I can swap the number 7, and number 1 injectors, and see if the problem moves with the injector. (I am not quite prepared to buy new ones just yet.....)

Anyone else?