Spark plugs??🤔

[chriskent85]

So I'm replacing the spark plugs in my 302 and noticed that the old plugs were the Autolite Platinum ap104. Well the reach on those are .706. The spark plugs that it calls for only have a .406 reach. So I figured I would replace them with the right spark plugs. From what I can tell it has the stock 302 steel heads but for some reason the .406 reach plugs won't even screw in to my head's because the tread is too far down in the head for the treads to catch. The previous owner tried to tell me that he had put gt40 heads on it but I have no clue. The plugs that have the .706 reach are for a 4.6L ford v8. Has anyone else had this issue?

 

[DirtDonk]

What are you using for your reference when buying the plugs with the .406 reach? The Bronco, or the GT40 reference?
If you look at the end of the heads, are there three vertical bars cast into it? Or four? Or some other design?
If in doubt, post up a pic of your heads.

But since you know for certain that the AP104's not only fit, but it ran with them (correct?) then cross-reference applications for that plug to see what is what.
Unfortunately they did change plug designs over the years, and even stock EB heads might have different models. You just need to know for sure what you have.

Good luck.

paul

 

[chriskent85]

It did run. Now I'm just curious to what heads I have. There is no bars on the ends. They look like just regular 392 steel heads. I find it odd that the regular spark plugs don't fit tho.

 

[Broncobowsher]

Previous owner said they changed the heads
You are using spark plugs for the original heads, not the ones he said he changed to.
Makes sense to me that the spark plugs don't fit.

Ford did a partial thread on the redesigned heads so you can't put a short plug in. You have to use a full length spark plug. That is they made the heads so you can't put the wrong plug in, like you are trying to do.

Get some 104s and put them in.

 

[Timmy390]

Pictures of the heads? How about a casting number?

LOTS of SBF heads out there........Lots of people who think they know what's what.....

Tim

 

[chriskent85]

 

[Timmy390]

That engine looks great......but to identify the heads......Need different pics.

Pic of the plug angle, exhaust port and under valve cover....Under the valve cover close ups would really help. Casting number should be in the middle....

Tim

 

[chriskent85]

I'll have to take the valve covers off when I get home. That's the only pic I have right now. This is the spark plug hole.

 

[EPB72]

Sp-482 motorcraft # are for late 80's crown vic 5.0..Those don't appear to be gt40 heads ..

 

[chriskent85]

Sp-482 motorcraft # are for late 80's crown vic 5.0..Those don't appear to be gt40 heads ..

I know they have no marking of the GT40 heads but they take the same spark plug. That is what has me scratching my head.

 

[Timmy390]

Casting numbers will tell the tell

http://lib.americanmuscle.com/files/contentgenerator/cylinder-head-upgrades.html/gt40castchart.JPG

Tim

 

[EPB72]

I know they have no marking of the GT40 heads but they take the same spark plug. That is what has me scratching my head.

AWSF32CK fit the below applications
Vehicle Fitment:
- 1979-1995 5.0L/5.8L using Ford Performance X Cylinder Heads
- 1979-1995 5.0L w/ 3-Bar GT40 Iron Heads
- 1979-1995 5.0L w/ 4-Bar GT40P Iron Heads
- 1993-1995 Cobra 5.0L
- 1996-2004 GT 4.6L 2V
- 1996-2001 Cobra 4.6L 4V
- 2003-2004 Mach 1 4.6L 4V

Sp-482 fit late 80's crown vic and other pass cars..
both these plugs will physically interchange but maybe wrong for intended stock application.. Is yours a stock application?

most of the trucks /vans 5.0/5.8l if not all used the short reach plugs if memory serves me correctly..

 

[chriskent85]

Now I'm really scratching my head(s) lol. Looked at the casting # and I can't come up with anything. The casting # is TJ12.

 

[Timmy390]

Is there a big T some place on the head under the valve cover?

Tim

 

[EPB72]

the casting # is on the under side of one of the center intake runners ,you woulld have to pull the intake to see it