I currently have the gap set at 25. These are autolite 3095 plugs. I am wondering if 25 is correct or would 30 be better?
The answer is, it depends. Try 0.030 inch. If she seems to run better, good. If worse go back to 0.025 inch. Each car and plug type seems to be unique.
It always seemed around .030 worked better for me.
.030". Dave, just for the heck of it, start your motor and let it warm to operating temperature. Once there check to see how tight the porcelain is in your spark plugs. A couple years ago I bought 4 brand new Autolites for my touring car. Foolishly I tossed the receipt on my way home. When I found the brand new Autolite's porcelain was extremely loose on all four plugs and realized the compression loss I was getting, I pulled the Autolites and carefully set them into the bottom of a trash can. Then I put my old motorcrafts back in and vowed to never run Autolite plugs again.
The porcelain didn't loosen until the motor was up to operating temperature. It sure seemed like a strange phenomenon to me and I wasn't able to get a refund for them because I couldn't find the sales slip.
I was taught, the gap should be set to the thickness of a thin dime. Good luck finding a thin dime these days.
That's got me buggered, we don't have dimes!!
Next question. Why would a 0.030 gap work better than a 0.025 gap? Longer spark ignites the gasoline better?
Although the T is low compression, around 45lbs. , if the engine is weak, then compression will be less.
Now a T with today's high compression heads, or dome topped pistions will boost that to 60lbs or more.
So plug gap is important for each situation [i.e. engine condition or modification].
Gap at .025 is better for a fat spark, and great running, at higher compressions. IMO. On my T's with high compression heads and magneto/coils.
I'm running a Z head, 280 cam, rebuilt engine Holley NH, TW timer, and Cameron Whitaker's electronic coils I gap my Champion X plugs at .035 The beast runs great!
Kevin, I forgot about you in the excitement in my life the last couple weeks. Between the fever and vomiting they stuck a tube through my liver and into my gall bladder. It drains into a little bag on my hip. I'm trying not to be preoccupied by this deal but with the next six weeks being spent in and out of the VA Clinic leading up to surgery at the end of August I'm in a fog. I recall we talked about coils and 12 volt systems and such. The best way to get ahold of me over the next couple months will be email or telephone. Please keep in touch.
I'll stay in touch. One of these weekends when you feel OK and I get a free moment, I'll buzz those coils over to you. Can you still drive or just feel too lousy to bother?