Again, my '89 4X4 302 has me scratching my head. I bought a set of plugs from the stealership the other day, SP415 (Motorcraft part # ASF32). Not knowing any better, and putting a tremendous amount of trust in the parts counter ape, I took his word that the SP415 were the correct plugs. When I got home and removed a plug from the truck, I noticed a big difference in the length of the threads on the plugs that were in the truck (AGSF42!!). I double checked the emmission sticker on the air box and low and behold, the sticker called for ASF42C. So, not only did the stealership sell me the wrong plugs, the truck currently has a wrong plugs (that are for GMC V6's!!).

So, assuming I have the correct heads (which I cannot confirm) for the year of the truck, why is it running so well with plugs that are about 1/4 inch longer than what is called for?? Have any of you run into similar situations? And finally, what is the correct plug for an '89 302?

I will go back to the dealer today and exchange the SP415's for SP450's and try those, but I am still boggled why the previous owner had AGSF42's installed.

Dan

 

You have the correct plugs installed in the engine.The part number ACF-42C is what you have in there now is a old part number the updated number is ACF-SP450.

 

A bit of a correction to my initial post-the plugs that are currently in the truck are AGSF32, not 42 as I indicated above.

I returned the 32's today and brought home 8 ASF42's and they will not screw into the head. I need a long reach plug, like the AGSF32's. I am completely stumped on this. The only reference I can find the AGSF32 fitting are numerous Chevy/GM products, Rangers, Sables and 351 newr trucks....no 302's. I am really scratching my head!!!!
Where are the casting numbers on the heads, I guess I'll have to start there.

Dan

 

Well after much research, I believe I am making headway regarding my 'problem'.
From the plugs that are installed in the truck (AGSF32), I was able to figure out 1 of 2 things -either I do not have the original heads on the block, or there is a completely different engine in the truck all together.
AGSF32 plugs were installed in 5.0l engines in 1993-5 Mustang Cobras and 1996-2001 Explorers. I believe that I have either the heads or a entire engine from one of those applications.
Mystery solved.....I'll gap them accordingly-.054 vice .044 and see what that brings!!

Dan

 

sounds like probably the heads are different.

 

Didn't the 5.0 explorer have the "GT40" heads?

 

GT40 heads maybe?

 

Dan, not sure of the answers to your questions.

What really intrigues me is the lack of knowledge at the dealership. When I started talking to the parts counter guys, they assured me that there was no way a 302 took any other plug than SP415 or SP450….full stop. Been like that since 196? when the first 302 became available. I asked a buddy of mine who is an old time gearhead, and he said that as far as he knew, the Mustang Cobras made their additional HP through the intake and fuel delivery-bigger throttle body and bigger injectors, and by different mapping in the ECM. Obviously, by the different spark plugs, the heads are different, how exactly, is the mystery.

If in fact I do have ‘high performance’ heads on the truck, I better do something to corral all those ponies I am not taking advantage of!!

I am still hunting around the net, trying to glean as much info as I can.

Dan

 

I think the exploders came with the GT40P heads which will have a weird Manifold bolt setup on them...they are staggered top to bottom......the casting numbers should be on the bottom edge of the head on...I wanna say the passenger side......what you should have should be E7TE heads.......I used to use Autolites then more than a few guys on here talked me into trying NGK V-Powers for my truck....at 2 bucks a piece I love em.......Luck

JR

 

Not for much longer. I answered this in the other post you have going, but I'll add it here to. What you have are E6TE heads, these were found on '86 mustangs and 5.0 cars up into the early '90 mainly. Obviously motors with these heads also found their way into some F150s.. you are not the first to discover these heads on a truck motor. These heads are the only other Ford heads besides the GT40P to take the long shank AGSF32 plug. BTW.. these are anything but high performance heads, great for producing TQ but needlessly restrictive unless heavily ported.

 

The heads on my 90 5.0 use the longer plugs which are not called for on the hood decal. I have two 5.0s from cars ( one is out of an 89 crown Vic and I think the other is from a T Bird) and they take the longer plugs. My 93 F250 5.0 takes the shorter plugs. I too am wondering if the heads on my 90 with a E7TE block are original or have been replaced

 

Thanks for the info Paul, greatly appreciated.

Using the info stated above, I searched the Motorcraft Spark Plug Guide to find the correct plug for a E6TE head. What I found were AWSF44, found in mid '80's 302's/5.0l cars. So I stop at the stealership and discover that the AWSF44s were a solid 1/4" longer than the AGSF32s (currently in the truck). Wanting to avoid any piston-spark plug interaction, I decided not to even bother trying the 44's.
Out of all of this, and only if I am thinking correctly, I am doubtful if the heads on my truck are E6TE, based solely on the spark plug application guide. I realize the only way will be to try and read casting numbers, but I don't want to take the top end apart if I don't have to.

Can anyone suggest another plug? I'm not in a bind or anything, and the old truck is running fine, but I want to be certain I am running the correct plug.

Thanks

Dan

 

Well, I went to my neighbourhood NAPA today and I bought a set of Autolite 2524s (cross referenced Motorcraft AWSF44) and installed them with no problems. Since these plugs are 1/4 " longer, I suspect the AGFS32s that I took out were not even poking into the combustion chamber. I'll see how these work.

It's amazing what people do to their vehicles and then wonder why it doesn't work right!!

Dan