CALL911 got me thinking

[popo8]

"Popo8, if you are getting a miss, you may want to check your spark plug gap. When I initially dyno'd my car I had an issue with the spark getting blown out at higher RPM pulls due to the larger gap. " CALL911

In another thread regarding spark plugs, CALL911 suggested doing a different gap, or atleast checking the gap.

Here is the basics.... my motor is all but 10-1 compression. and right now in the high 7 lb boost range (closer to 8)

Higher RPMs giving me a misfire (4,000 rpm+) where should I gap my plugs.

again I run 1-2 degree colder plugs gapped at .028..... (i think, maybe .030)

[Z28pr0jekt]

That gap seems right.. if not even too small for only 8psi but it is 10:1.

I would really wanna point your misfire in another direction but I can't say which direction.

What is your fuel pressure doing when the miss occurs?
Getting any knock?
How much timing are you running?
Plugs show signs of detonation?

[popo8]

That gap seems right.. if not even too small for only 8psi but it is 10:1.

I would really wanna point your misfire in another direction but I can't say which direction.

What is your fuel pressure doing when the miss occurs?
Getting any knock?
How much timing are you running?
Plugs show signs of detonation?


Well fuel pressure looks great, car is still FAT as hell on the wide band... all the way through.

We keep throwing timming at the car, but the misfire is a hinderance.

to be honest, when I put the NEWEST motor in, we strapped it to the dyno with the same tune it had from the prior motor, and it made 13 more hp alone with a beautiful power curve. We attempted to make the tune better and the LT1 edit connector took a crap, so we waited 2 wks for a new one.

In those two weeks we put in a new set of plugs, and that was when the misfire showed up when we strapped it down.

I learned later that my frends son dropped a box of 4 of the plugs when I was not at the shop, and Im wondering if one or more got damaged...

what do you guys think about that idea....

[Z28pr0jekt]

check to see if the plugs are arching at night, always possible the porcelain cracked.

what plugs are they again?

[popo8]

The autolites... (dont know the number off hand). 1-2 deg colder.

[Fastbird]

Did you change brand of plug when you swapped them in??? How did you old plugs look?? Maybe swap those back in for giggles and see if the issue persists? Possibly you got a different plug (I've had it happen, a TR6 in a TR55 box)?

That .028-.030 gap should be fine. I'm going to be running .028 on a BR7EF plug on my vette, 9.25:1 @ 14lbs and shouldnt' have a worry.

[BLOWNDFIZ]

1 broken plug will cause havok. Trust me. Since you know yours were dropped just replace them and gap around 32. That's what I'd do.

[popo8]

I have two new boxes in my drawer at the shop. now its a matter of finding time...

Now I am hearing the gap Im using is good, but BLOWNDFIZ is saying larger gap... what do I do.....?

[popo8]

1 broken plug will cause havok. Trust me. Since you know yours were dropped just replace them and gap around 32. That's what I'd do.


How much boost are you running?

[BLOWNDFIZ]

How much boost are you running?

13-15 right now. Just got a new crank pulley from Blownformula so that will probably be go up a pound or two. I run .30 gap.

[popo8]

Did you change brand of plug when you swapped them in??? NO

How did you old plugs look?? PERFECT, maybe a little fat

Maybe swap those back in for giggles and see if the issue persists? got bran new ones...

Possibly you got a different plug (I've had it happen, a TR6 in a TR55 box)? Never thought of that....

[Fire67]

Maybe too cold for the amount of boost? At that level, one step colder should be just fine on the plugs.

How fat is it running? Too fat will cause a miss due to incomplete combustion, but Im talking in the low 10's and richer on the AFR's.

[popo8]

No. not that bad.

[CALL911]

If you are running around a .028 to .030 that gap should be good enough not to have the spark blown out (especially running 7#'s of boost). My initial gapping was much wider than that, and was the cause of my initial high RPM miss up top, until I adjusted mine to .028 (keep in mind that my boost was around 15#'s).

Remember, this is just one possible answer to your problem. If you are running the proper gap in your plugs, your high RPM miss could be caused by something else. Are all your plug wires 100% good? Even a tiny slit or melt can cause a miss. What ignition coil and box are you running? These are some other considerations you need to think about.

[popo8]

I am running a blaster coil, MSD 6AL box, and MSD BILLET OPTI....

Honestly, like I stated before, I believe the problem is a possible broken plug. Since the first time on the dyno the curve was smooth, but the LT1 EDIT would not communicate.. brought the car home, put new plugs in and when we returned when the LT1 EDIT was fixed, I had a miss above 4g....

Wish I woulda known the box of plugs had fallen before I swapped em, but shit happens.... fingers crossed, I got a bunch of shit I wana change and its back tot he dyno...

[popo8]

Just wanted to show my instal of the 6AL

[BLOWNDFIZ]

Just wanted to show my instal of the 6AL

Where do you keep you registration for when you get pulled over???:jest:

[popo8]

Where do you keep you registration for when you get pulled over???:jest:


Center console..... but I have a GET OUT OF JAIL FREE license plate....

[PUMPKINMAN]

Center console..... but I have a GET OUT OF JAIL FREE license plate....
must be nice.:whistle: do you buy those at walmart or academy? lol

[popo8]

must be nice.:whistle: do you buy those at walmart or academy? lol


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