TOPIC:

Since I have a set of Accel coils installed by the PO on my SR, I was poking around the Mr. Gasket site for information. Reading through the instruction sheet, I came across this little gem:

11. As ACCEL's coils are quite powerful and deliver a much stronger spark than original equipment coils, considerable care should be taken after their installation to be sure the carburetor jets on your model are adequate. A "hotter" spark normally requires larger jet sizes in order to maximize power output and prevent a possible lean fuel condition that could result in an overheated or possibly damaged engine.

Followed by this:

ACCEL cannot be responsible for consequential engine damage caused by the installation of these coils if the consumer does not address the possible resultant lean fuel condition the installation of these coils may cause.

Now, I lay no claim to being an expert on things related to engines, but this is the first I've heard of this. Just how can the spark change the mixture? The fuel mixture will burn at a given temperature depending on the ratio of fuel to air, not what ignites it. Am I off base or is ACCEL's legal department just covering their @$$?

For the record, the last time I checked the plugs in the SR (last year?), they looked normal.

yeah id say you are safe:P

I'm by no means an expert, but I also don't see how a stronger spark could result in a lean mixture, I think the key word they had was POSSIBLE, they were probably covering their ass with that disclaimer, if the plugs read ok I don't think there's much of a problem anyways

a hotter spark is going to burn the fuel more efficantly sp, so if by some small chance you were right on the edge of being way lean with a bad spark and you changed to a real hot spark at high rpm you just might in theory cause a problem. but sounds like a lawyer cover his butt deal to me

I think the theory is possible and this is why... I have a 66 Impala with a 283 punch out to a 301 with a 464 lift cam and a Holly 600. When I first put this motor together, I had the stock distributor. The plugs were fouling like crazy. So I put an HEI w/ a Accel HO coil in it and I even bumped up the stock gap from 32 to 38. That made a huge differnce. Weak spark not enough to burn the gas. If I ran the HO coil with everything stock The hot spark could make my car run lean. You could shorten or legthen the gap to compensate for the much hotter spark. I had to mess with the gap on my car for a bit untill I got it where I wanted. I also ran a colder plug.

I was speaking with tounge in cheek, the hot spark is not going to make it run lean, its going to run better because the weak spark was not getting the job done, cyl compression, it changes the whole spark issue, it takes more voltage to fire a spark under compression than in the open air.
I run a HOT msd dist on one of the race cars, super cold plugs and a gap of .025. you run a colder plug because the cyl temp goes way up under racing loads, the hotter plug would cause pre ignition because it is staying hotter after the time of fire and with a hot cyl and a hot plug the gas will fire at erratic times, and that plays hell on bearings and pistons

You are right BSKZ650. I think as a rule though when putting a hotter coil you will increase the gap of the plug. Your getting more spark from the coils so you can gap the plugs more to well, get more spark to burn the fuel.

Here is a good article on Ignition & Coils 101

Don't mean to interupt this thread but do you mean that with my Andrews coils, accel wires, WG coil mod, Dyna S, that I could or should open up my plug gap from stock?

Bluemeanie wrote:

Don't mean to interupt this thread but do you mean that with my Andrews coils, accel wires, WG coil mod, Dyna S, that I could or should open up my plug gap from stock?

Opening the gap, even a little, stresses the coils and the ignition more. The Dyna and Andrews may handle it, but if your bike runs great with the stock gap, keep it stock. If opening the gap makes it run noticeably better, look into the carburetion for possible jetting issues, or the motor for condition issues.

you dont want to increase the gap at the plug, under a load, compression, it takes more voltage to make the arc, which is going to force thew coils to work harder and increase the chance of a miss fire, thats why as the plug gap increases the engines run less efficant.
I always aet the plug gap to the smallest possible

Cool, thanks guys. I run stock gap and the bike runs like a raped ape...

Now that we're over onto plug gap, the ACCEL documentation also specifies a plug gap of 0.035" which mine on the SR are set to with no firing issues. I just checked the plugs this evening and they are a nice light tan and the electrodes are burning clean. This is with about 2000 miles using the ACCEL coils.

I did find another performance manufacturer that warned of a possible lean condition with their product, Nology HotWires . I know nothing about this product, it's just a web page I stumbled onto.