Any reason to replace spark plugs if the car runs fine? Just hit 100k.

[dman102]

Hi all,

I just hit 100k, so I figured I would replace all fluids and get me some new spark plugs. However after reading all of the issues not just related to the removal of spark plugs but also for the installation of new ones, I am wondering if it is even worth it? I ordered autolite HT1s from rockauto, they were the only plug that they even had 8 of for sale. They just got here and I started reading more reviews about people having issues with the gap out of the box. Some F150 guys even saying they had issues with the electrodes coming off into the engine soon after installation, just general QC issues it seems.

Anyone have any input? My car runs fine as is, really not sure if it's worth it to replace the plugs when it seems like a gamble every step of the way. However I am not the original owner and have no idea when they were last replaced.

 

[86GT351]

Every spark plug needs to have a gap check. At 100k they are worn for sure.

 

[07 Boss]

Have you never pulled the plugs before? Yes I would definitely change them out.

 

[dman102]

Every spark plug needs to have a gap check. At 100k they are worn for sure.

how can you check gap on these plugs?

 

[dman102]

Have you never pulled the plugs before? Yes I would definitely change them out.

Thanks for your reply, was just looking for confirmation.

 

[ZwookY]

Be prepared for them to break! I did mine around 100K and 7 of 8 broke!
Tried everything I'd seen online but they still broke and I had to buy a special tool.
30 minute job took a whole day!

 

[dman102]

Every spark plug needs to have a gap check. At 100k they are worn for sure.

So the Autolite HT1s (recommended on many forums including this one) come pre gapped at 0.035”. But apparently the consensus is that on a stock 3v, the gap should be set at 0.045”? So which is it? Do I need to return the autolites? I’m under the impression that it is very difficult to gap these plugs without an expensive tool from steeda. If so why does everyone recommend these plugs?

 

[86GT351]

So the Autolite HT1s (recommended on many forums including this one) come pre gapped at 0.035”. But apparently the consensus is that on a stock 3v, the gap should be set at 0.045”? So which is it? Do I need to return the autolites? I’m under the impression that it is very difficult to gap these plugs without an expensive tool from steeda. If so why does everyone recommend these plugs?

What is the reasoning your looking to run the HT1s? Really suggested for a power adder car or built motor

 

[dman102]

What is the reasoning your looking to run the HT1s? Really suggested for a power adder car or built motor

I thought it was the HT0’s that were suggested for power added cars. I was under the impression that HT1s are for stock vehicles. Even saw some posts saying the HT1s are the same as the stock motorcraft plugs just under a different name. Oh well, guess I’ll return the HT1s

 

[JC SSP]

If I remember correctly… HT0 are one heat range cooler. I have used them without any issues on a mostly stock engine.

 

[07 Boss]

HT1 is the regular plug and should come pregapped at .045 to .050 and for later s197s I think they increased the gap to .055. Anyways, the HT0s are one degree colder than the stock HT1s and usually reserved for cars running boost, nitrous or higher compression. I believe they are supposed to be gapped at .035 from the factory but the one time I ran them I gapped them at .028. Currently running Accel spark plugs (one degree colder) gapped @ .028 running 11.5 psi of boost.

 

[86GT351]

I thought it was the HT0’s that were suggested for power added cars. I was under the impression that HT1s are for stock vehicles. Even saw some posts saying the HT1s are the same as the stock motorcraft plugs just under a different name. Oh well, guess I’ll return the HT1s

You are correct. My bad

 

[dman102]

HT1 is the regular plug and should come pregapped at .045 to .050 and for later s197s I think they increased the gap to .055. Anyways, the HT0s are one degree colder than the stock HT1s and usually reserved for cars running boost, nitrous or higher compression. I believe they are supposed to be gapped at .035 from the factory but the one time I ran them I gapped them at .028. Currently running Accel spark plugs (one degree colder) gapped @ .028 running 11.5 psi of boost.

Per the autolite website, HT1s and HT0s both come pre gapped at 0.035.
HT0 Heat range: 12
HT1 Heat range: 11

Autolite HT0 High Thread Pro Spark Plug

Autolite High Thread Pro spark plugs are an OE patented design exclusively for Ford 3V engines. Find vehicle compatibility and technical specifications for Autolite HT0 High Thread Pro Spark Plug.

www.autolite.com

Autolite HT1 High Thread Pro Spark Plug

Autolite High Thread Pro spark plugs are an OE patented design exclusively for Ford 3V engines. Find vehicle compatibility and technical specifications for Autolite HT1 High Thread Pro Spark Plug.

www.autolite.com

I'm unfamiliar with spark plug heat ranges and what the numbers mean, but it does seem like they both come pre-gapped at 0.035. It also appears the HT1s are colder? Strange because I've heard everyone say a stock 3v should be gapped at 0.045. Website says opposite of what everyone else is saying.

 

[JC SSP]

Per the internet…

In Autolite spark plugs, A higher number indicates a hotter plug, while a lower number indicates a colder plug.

So if this is true, then HT1 (11) are cooler than the HT0 (12). I could have sworn the HT0 were one heat range cooler…

Regardless, if you really have 100k on stock plugs it’s time for a new set.

 

[GriffX]

I would also measure the resistance of the coils they are wear parts too. Can't remember the exact value I think it was
around 4 kOhms.

 

[dman102]

Per the internet…

In Autolite spark plugs, A higher number indicates a hotter plug, while a lower number indicates a colder plug.

So if this is true, then HT1 (11) are cooler than the HT0 (12). I could have sworn the HT0 were one heat range cooler…

Regardless, if you really have 100k on stock plugs it’s time for a new set.

I get that now, I do plan on replacing them. The battle now is just to figure out which plugs to get. There's so much conflicting information. Nearly every forum on the internet says the HT0's are cooler and for boost applications. I suppose it makes more sense to just find some motorcraft plugs. These are gapped at 0.054 per ford's website. Any good sources?

 

[07 Boss]

Per the autolite website, HT1s and HT0s both come pre gapped at 0.035.
HT0 Heat range: 12
HT1 Heat range: 11

Autolite HT0 High Thread Pro Spark Plug

Autolite High Thread Pro spark plugs are an OE patented design exclusively for Ford 3V engines. Find vehicle compatibility and technical specifications for Autolite HT0 High Thread Pro Spark Plug.

www.autolite.com

Autolite HT1 High Thread Pro Spark Plug

Autolite High Thread Pro spark plugs are an OE patented design exclusively for Ford 3V engines. Find vehicle compatibility and technical specifications for Autolite HT1 High Thread Pro Spark Plug.

www.autolite.com

I'm unfamiliar with spark plug heat ranges and what the numbers mean, but it does seem like they both come pre-gapped at 0.035. It also appears the HT1s are colder? Strange because I've heard everyone say a stock 3v should be gapped at 0.045. Website says opposite of what everyone else is saying.

When you have a higher heat range it means it's a colder plug. Plugs are designed to operate at certain temps. When you run higher cylinder temps you need a plug with a higher heat range or a colder plug. When you refer to a colder plug it refers to the ability to shed heat better. So a colder plug is made for a higher heat range. It's like gear ratios. The higher the ratio number the lower the gear. The higher the heat range the colder the plug. Colder plugs are made for a higher heat range.

 

[JC SSP]

Just chatted with "Robert" at Autolite... He said HT0 is cooler than HT1. He could not explain anything else regarding the spark plug specifics. I suggest someone else ask/research to see if we get the same response.

I had HT0 in my 06' and switched from Brisk to HT0 in my 05'. All gapped at .045 and still running strong.

 

[07 Boss]

Just chatted with "Robert" at Autolite... He said HT0 is cooler than HT1. He could not explain anything else regarding the spark plug specifics. I suggest someone else ask/research to see if we get the same response.

I had HT0 in my 06' and switched from Brisk to HT0 in my 05'. All gapped at .045 and still running strong.

Yes the HT0 is the colder plug with a higher heat range.

 

[Autokyrios]

I changed mine at 65k but just for the heck of it and not any mechanical reason. Not a one broke but I took my time and really hosed them down with penitrant. Also, with an aluminum block, make sure it's bone cold. Aluminum cross-threads and rips-out like butter so be careful. The tool for removing a broken plug is widely available these days.

You really need to pay attention to the thread size. As others have mentioned already, they changed the spark plug threading halfway through the model (even halfway through a production year...2007). If you take your VIN to a dealer they can identify which you have, or just wait till you pull them out to buy new ones as you can measure them directly then.

Oh, and goes without saying but make sure you work clean. You do NOT want anything to go down into your head when you pull the plug out.