to everyone with the Ford Escort coil pack mod..

[match417]

So I haven't ran my bike with the Escort coil pack yet, I've had to fix some things and pull my engine out. It's back in now and ready to fire up almost, I have to do some things to my header and change out my waterpump, but it's almost ready.

Anyway, I have a question. My spark plugs are gapped to 0.050 inches now, compared to the FZR's 0.028 stock. I made the gap that large because that's the recommended gap for the Escort the coil pack came off of and I don't want a smaller gap so the hot spark destroys the tip of the spark plug. So now to my question, I'm a little worried about the spark plug tip possibly hitting the piston since the FZR has a compression ratio of 12:1. I haven't fired it up yet because of the other stuff I have to do, but the last thing I want is destroyed spark plugs. I'm sure most everyone else that did the escort coil pack mod increased the gap on the spark plugs like I did, did you guys have any problems with this?

[sweekster]

If it were me and I had concerns regarding the spark plug gap, I would start with a smaller gap and work up instead of just going with something possibly too large and hoping it doesn't kiss my pistons...

[haro504]

how much damage could it do the tip is pretty soft in the first place and i dont see that small of a difference hitting anyway

[match417]

since I just painted my frame and all of my other stuff I don't want to lean it on anything for fear of rubbing the paint or damaging something. I guess I'll just drain the oil again, I think I have some old bottles..thanks guys!

[sh0rty77]

There should be enough room there.
If there was such little space there some people would be having problems simply by how tight the do there plugs up.
I would be more looking into the actual spark burning/pitting the top of the piston rather than it hitting it.

I would turn bike over to top dead center pull a plug out (no1) and measure the depth from plug seat to top of piston,
and measure a plug from seat to the end.

[the_finch]

There should be enough room there.
If there was such little space there some people would be having problems simply by how tight the do there plugs up.
I would be more looking into the actual spark burning/pitting the top of the piston rather than it hitting it.

I would turn bike over to top dead center pull a plug out (no1) and measure the depth from plug seat to top of piston,
and measure a plug from seat to the end.

+1

If you pull the timing cover, you could also use the stator cup to turn the motor over by hand to see if if touches,

[match417]

There should be enough room there.
If there was such little space there some people would be having problems simply by how tight the do there plugs up.
I would be more looking into the actual spark burning/pitting the top of the piston rather than it hitting it.

I would turn bike over to top dead center pull a plug out (no1) and measure the depth from plug seat to top of piston,
and measure a plug from seat to the end.

that's actually what I did when I had the engine out, but I didn't have anything small enough to measure so I just used two q-tips, one went to the piston and the other went to the spark plug seat and I held them together and pulled it out. I did it a few times and it was all the same, but it isn't an exact measurement, and it was about 3/16ths (5mm) away from the piston just by me marking it with my finger. And giving it a 1/16th margin of error for safety still puts it kinda close to the piston. Since it was so close by me measuring I thought I would post up the question to see if anyone had a problem with it, just to be safe.

And as far as scorching the piston with the spark, I doubt that since the spark doesn't happen at 0 degrees top dead center, it happens a little after top dead center usually. And since the coil pack creates a 1/4 inch (6mm) maximum arc, and I have about a 0.05 gap (1.27mm) plus 1/8th (3mm) from spark plug tip to the piston, and factoring in how the piston should be maybe 1/16th of an inch (1.5mm) away from TDC (that's an approximation) by the time the spark arcs, the plug tip is about 1/8th (3mm) thick, then if my depth measurement is right (crosses fingers) I shouldn't have to worry about the plug arcing to the piston, since the max arc gap is 6mm, even if the piston was at top dead center when the spark arc'd I would still have 7.27mm, it will happen a little after TDC so I'm safe I think. If I mis-measured and the depth is 1/16th (1.5mm) then that drops the arc just below 6mm while at TDC, but the spark shouldn't be strong enough to damage the piston since that's the weakest point. Even then, electricity chooses the path of least resistance, so it will hit the wall of the plug first even if the firing tip wasn't there or was so scorched there was no spark. I like math....as you guys can tell.

I'm more worried about the possibility of the pistons hitting the spark plug tip, but since no one has chimed in and said they have had that problem, then either no one has gap'd their plugs this high, or they have gap'd them that high and it's not a problem.

[reelrazor]

A) the arc to piston issue is a non-issue-the piston is BY FAR a poorer path to ground than pretty much anything else in the combustion chamber.....sitting on a film of oil, on a rod that is on a film of oil...sliding in a cylinder on a film of oil..it is unheard of (except maybe on tuner car/gsxr squid forums)-besides that..I bet at least one of the valves is closer than the piston will ever be to the plug gap on the 'waste spark' stroke.

B) You could install one plug with the ground electrode bent to a 5mm gap and then slowly roll the engine over by hand and see where it ends up, for a definitive answer on clearance

BTW: base idle spark advance puts the spark event at 5° BEFORE TDC....NOT after....this quickly moves to 30some° BTDC

[match417]

I bet at least one of the valves is closer than the piston will ever be to the plug gap on the 'waste spark' stroke.

Oh yeah, I didn't even think about that, but the pistons aren't perfectly flat, they have dents to make room for the valves. So the valves would drop below the spark plug tip, but the pistons are shaped to accept that. At least I think the FZR pistons are like that, not all pistons have that.

Wait I just thought of something..I have a YZF600 head in my room that I could put a plug in and see how low it drops. The pistons are flat and the combustion area of the head is dome-like. I'll play around with that, that would give me a good idea of how deep they sit.

[Lasse]

So I haven't ran my bike with the FORD Escort coil pack yet,
I've had to fix some things and pull my engine out.
It's back in now and ready to fire up almost, I have to do some things to my header and change out my waterpump, but it's almost ready.

Anyway, I have a question.
My spark plugs are gapped to 0.050 inches now, compared to the FZR's 0.028 stock.
I made the gap that large because that's the recommended gap for the Escort the coil pack came off.

FZR has a compression ratio of 12:1.

What is this thing : .....to use a Car spark coil in the FZR600 ?

Can someone explain for me ?