spark plug gaps for coyote

[twistedneck]

Using the stock plugs - Motorcraft sp519 iridium. one set gapped at 0.035 the other gapped at the factory setting - 0.049 to 0.053. I run a 93 tune w/ headers and the usual mods.

With the tight plugs I was thinking that 0.035 was too tight to get good efficiency and burning since its basically a stock boss engine w/ cj cams. so I put in the big gap factory set.

First thing I notice? It takes a good second longer to fire up the car here in 10F Michigan cold weather.

should I re-gap these down to 40 or 45?

edit: I just started it after sitting in the cold all night, its 23F now. it actually struggled to start but it started after 2 seconds. drove it around for 35min to warm it up, then tried to start it again and it fired much quicker.. fired up normally.

Thanks!

 

[el jefe 302]

You want to run the biggest gap possible without spark blowout.

Why are you trying to close down the gap anyway? Are you running nitrous or boost?

 

[twistedneck]

You want to run the biggest gap possible without spark blowout.

Why are you trying to close down the gap anyway? Are you running nitrous or boost?

No, just n.a. I was under the wrong impression that I needed a closer gap for e85 that I'm changing to in a couple weeks.

I also was told by my cousin that n.a. Ls engines are 0.055" gap even if they are stout builds!My car runs great now and fires right up. Runs like an animal actually.
Should I re-gap for e85 next week? Does e85 need less gap?

 

[el jefe 302]

Let me ask my tuner, because I'm also going e85. But so far he hasn't said anything about closing the gap.

Aed is tuning the car.

 

[twistedneck]

Let me ask my tuner, because I'm also going e85. But so far he hasn't said anything about closing the gap.

Aed is tuning the car.

Ask him for me too AED is also tuning mine.

 

[Konablue10GT]

FWIW, We tested spark plug gap changes on our 93 oct 500rwhp N/A coyote and didnt see any changes in rwhp or rwtq. The range went from .055, .050, .045 and .040.

I believe Shaun had the same results playing with plug gap.

I put the plugs back to .050 and called it a day.

Adam

 

[twistedneck]

FWIW, We tested spark plug gap changes on our 93 oct 500rwhp N/A coyote and didnt see any changes in rwhp or rwtq. The range went from .055, .050, .045 and .040.

I believe Shaun had the same results playing with plug gap.

I put the plugs back to .050 and called it a day.

Adam

That's great information. Did you ever try E85?

 

[01bluesnake]

You really won't see a gain in playing with spark plug gap on mild n/a motors, typically heavily built where extreme amounts of fuel are being dumped at wot which then some can be had from a better burn. Under a boosted or nitrous application gains can be seen by using a bigger gap that allows a more complete cylinder burn of all the fuel being dumped in without allowing spark blow out. This is no different than spark plug company's that shows gains from spark plugs that can give a hotter spark like Brisk, E3, Denso and so on. Opening the gap allows the same effect of a wider burn as long as the spark can sustain the cylinder pressure and fueling demand. You will see bigger gains on cars with poor combustion chamber design vs any Hemi style.

 

[hasty]

How does the car run!? Any videos of the car idling?

How's the drivability?

 

[twistedneck]

How does the car run!? Any videos of the car idling?

How's the drivability?

I'll take the go pro out next drive any specific view? idle for sure.. then maybe the door.

Michigan has been snow -ice-salt-repeat for the last 2 straight weeks soon as it gets nice i'll get the vids. Idle is still set at 900 for some reason that's how AED wants it but i'm going to request a lower idle during the next tunes.

So its still fine, no piston to valve problems.

 

[hasty]

I'm really curious about the drivability. I'm going to be using my setup almost like a daily driver. I wouldn't mind just hearing the idle and exhuast, but it's your car lol.

Does it have a pump gas tune right now, or are you just limping it around until you get it tuned? I suppose you had to get a tune of some sort for it to run right with a bigger intake pipe, but I didn't know if that was already on your car before you did the motor work.

 

[twistedneck]

I'm really curious about the drivability. I'm going to be using my setup almost like a daily driver. I wouldn't mind just hearing the idle and exhuast, but it's your car lol.

Does it have a pump gas tune right now, or are you just limping it around until you get it tuned? I suppose you had to get a tune of some sort for it to run right with a bigger intake pipe, but I didn't know if that was already on your car before you did the motor work.

No big changes apart from cam and heads so first base 93 tune is pretty good. Idles normal just high.

Floored it one time at 4000 in third. Hit 4500 and blew up the tires to 6500. Seems fast and no issues w driveability at all

Was worried about plugs but that is a non issue now.

 

[hasty]

I wouldn't expect it to make drastically more torque than stock, but I'd expect significantly more high rpm power.

I could be wrong, but I'd guess that lower gears might make the car an entirely different monster with heads/cam.

I'm probably going to put 4.10's in my notchback. It's got a T56 though.