New Owner Spark Plug Gap Question

[Shawn Farbman]

First time Mustang owner , not new to muscle or fast cars but this is my first Fox Body ! My first inquiry has to do with spark plugs and gap , the car has been painted and there is no sticker on the hood. Using search I am finding conflicting info some say .42-.45 others say .50-.52 . This is GT 5.0 HO engine , convertible. I pulled the plugs as general maintenance and put in new ones , the old ones were gapped at .44 . Now having said that I also noticed that from a stop in 1st gear the car pulls very nice , but once you get into higher gears , there is no pull at all just a slow acceleration , unless you engage the kick down. New fuel filter , new air filter , cleaned carbon from Intake and cleaned MAF , still same lethargic acceleration after 1st gear. This points towards the basics I assume fuel/air/spark so as I travel that road , I wanted to make sure I have gapped the plugs properly.

 

[revhead347]

What kind of plugs did you put in it? Go ahead and gap them down to .035" and see what happens.

Kurt

 

[General karthief]

42-45 is good, you got a heavy convertible and an auto transmission, I had a 92 lx vert, they come with a 3.25 rear gear, a little sluggish off the line, a 3.55 or a 3.73 will wake it up a bit. Check the timing, a little advance will help too, 12 or 14° , stock is 10°, there is a thread in the 5.0 tech/how to section that lists common modifications that may help ya get a little more fun in sun.

 

[Shawn Farbman]

Thanks for the replies ! It was indeed the timing , it was set at about 7.5 degrees ....I bumped it to 10.5 and it runs much stronger , will try that for a few days and slowly make my way to 12 !

 

[cleanLX]

With the stock motor, coil, dizzy and wires I always ran the factory spec... 0.54. and 14* timing... always ran strong.
I don't know why you would run less gap... less spark seems like, well, less to me.

 

[Shawn Farbman]

With the stock motor, coil, dizzy and wires I always ran the factory spec... 0.54. and 14* timing... always ran strong.
I don't know why you would run less gap... less spark seems like, well, less to me.

Thanks ! I was getting conflicting info via different spec sheets calling for .44 on a 90' 5.5 HO engine , to others saying .54 .

 

[General karthief]

My emissions sticker says 48-52 plug gap so 54 would not be bad with timing set at 14°

 

[Mustang5L5]

The older 5.0's has a smaller gap. At some point in the mid 80's, the ignition was improved so that a larger gap could be used. Ideally you want as large a gap as possible unless you are running a power adder. Stock gap for a 1987+ range is 0.052" - 0.056", so most people target 0.054".

Now, aftermarket ignition components, you can probably increase that even further, especially with a EDIS-8 or COP conversion. For the sake of your question.....0.054"