Spark Plug Question

Jarvis · Sep 1, 2013

I got some plugs and wires from LMR.

Plugs: Motorcraft: SP- 406, AGSP32C
Wires: FRPP 9mm

Question what should the Gap be? I saw the table that shows gaps but these plugs weren't on there. I
don't know the timing, or how to check. Mods are in the siggy. Thanks for the help guys.

madspeed · Sep 1, 2013

stock gap should be fine for you

From "The Official Ford Mustang 5.0 Technical Reference & Performance Handbook 1979-1993" Ford Racing Part No. M-1832-Z4
Page 274
"Spark Plug Applications" table
Year---------Engine--------------Motorcraft number-------Gap (inches)
1979---------5.0L (49 state)-----ASF-52------------------.050
1979---------5.0L (california)-----ASF-52-6---------------.060
1980---------4.2L (all)-----------ASF-42------------------.050
1981---------4.2L (all)-----------ASF-52------------------.050
1982---------4.2L (all)-----------ASF-52------------------.050
1982-1985---5.0L carbureted-----ASF-42------------------.044
1982-1985---5.0L CFI------------ASF-52------------------.050
1986--------5.0L H.O.------------ASF-34 or 44------------.050
1987-1993---5.0L H.O.-----------ASF-42------------------.044
1993--------5.0L GT-40 (Cobra)--AWSF-42C---------------.050

1. Factory electrode gap specifications are shown on each Mustang's VECI label that is affixed underhood. The relatively wide gaps specified created the fat, long-duration spark needed to ignite the lean mixtures prescribed for most normal operating conditions.
2. Most non-Cobra 5-liter motors typically run well with spark plugs gapped at .052 inch. For normally aspirated engines in high-performance service, a plug gap between .040-.045 inch is suggested by many tuners. Those same sources also suggest .028-.034 inch in turbocharged, supercharged, and nitrous-fed five-ohs.

Jarvis · Sep 1, 2013

So .044? They're out of the box at .51. Also seems to be running a tad rich, does that change anyything?

madspeed · Sep 1, 2013

yep, .044. As far as running rich, pull your codes even if the cel is not on

Jarvis · Sep 1, 2013

I tried to pull codes, My CEL doesn't come on at all. When i start it, and when I jumped the diag connector

madspeed · Sep 1, 2013

pick up the cheap equus ford code reader. it plugs directly in to your diag connector and does everything for you

http://www.amazon.com/dp/B000EW0KHW/?tag=stangnet-20

Jarvis · Sep 1, 2013

That's not a bad idea, I might pick one up at the store later.

madspeed · Sep 1, 2013

have had mine for a dozen years

Jarvis · Sep 1, 2013

Nice! I've been waiting at least that long to get my Fox

stykthyn · Sep 1, 2013

that reader is a god send

madspeed · Sep 1, 2013

@stykthyn, how do you do initiate the koer test? I can't semyo locate my manual and haven't done that on in a long ime

stykthyn · Sep 1, 2013

I plug the tester in power it up and then start the car. the manual has more details on how to extract more info such as the cylinder balance test. you have to press the gas to floor when the reader starts to flash or all testing stops and the reader cycles down.

If you try to plug in after the car is running it wont pull any codes, or at least I've never been able to.

vfast · Sep 1, 2013

51 is ok

JD1964 · Sep 1, 2013

I just ordered one of those digital code readers from Amazon for future use.

On the question of spark plug gap, I'm running Autolite #25's. The label under the hood on my '92 says 52-56 for the gap. I set my plugs at 54.

Should I pull them back out and re-gap to 44 instead?

mikestang63 · Sep 1, 2013

The 54 is the recommended gap from the factory. You should be fine there but if you want tighten the gap to 44 and see if it impacts the performance. Equally important is what type plug you run.
Those heads call for a certain size and reach plugs - 14mm by 3/4". When I had E brock heads I ran the same plugs ( Autolite 3924's one step colder) gapped at 54.

http://www.framcatalog.com/Competitor.aspx?b=A&pn=AGSP32C&em=True

http://www.edelbrock.com/automotive_new/mc/cylheads/ford/sb_perf_rpm.shtml

65ShelbyClone · Sep 4, 2013

Why blow $25 on a code reader that only works with old Ford EEC-IV systems when you can pull codes and run self-tests with a scrap piece of wire and a $0.99 12v test light? If you have a working CEL, then all it takes is the piece of wire.

Plug gap is more reliant on the ignition system and induction than the plug itself. I would use the stock gap with a stock TFI ignition and no power adders or high compression.

Jarvis · Sep 4, 2013

65ShelbyClone said:
Why blow $25 on a code reader that only works with old Ford EEC-IV systems when you can pull codes and run self-tests with a scrap piece of wire and a $0.99 12v test light? If you have a working CEL, then all it takes is the piece of wire.

Plug gap is more reliant on the ignition system and induction than the plug itself. I would use the stock gap with a stock TFI ignition and no power adders or high compression.

I dont have a CEL, i tried.

JD1964 · Sep 4, 2013

65ShelbyClone said:
Why blow $25 on a code reader that only works with old Ford EEC-IV systems when you can pull codes and run self-tests with a scrap piece of wire and a $0.99 12v test light? If you have a working CEL, then all it takes is the piece of wire.

Plug gap is more reliant on the ignition system and induction than the plug itself. I would use the stock gap with a stock TFI ignition and no power adders or high compression.

I have a habit of blowing $25 on all kinds of things. I see your point though. I used to get the codes from my old GM OBD1 cars with a paperclip in the diagnostic port and count the CEL flashes.

madspeed · Sep 4, 2013

you can still pull the codes without a cel. Theres a how to in jrickters surging idle checklist thread. That being said, I still prefer my handy $25 reader, guess i'm getting old

65ShelbyClone · Sep 5, 2013

Jarvis said:
I dont have a CEL, i tried.

I know, I was making the indirect general statement that in a worst-case scenario, all you need is a $1 light and a piece of wire.

Spark Plug Question

Jarvis

Member

madspeed

Colonel Mustard

Jarvis

Member

madspeed

Colonel Mustard

Jarvis

Member

madspeed

Colonel Mustard

Jarvis

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madspeed

Colonel Mustard

Jarvis

Member

stykthyn

I want to measure mine. It doesn't look that tall.

madspeed

Colonel Mustard

stykthyn

I want to measure mine. It doesn't look that tall.

vfast

Member

JD1964

there is enough sticking out to grab on to

mikestang63

65ShelbyClone

Jarvis

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JD1964

there is enough sticking out to grab on to

madspeed

Colonel Mustard

65ShelbyClone

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