2005-2014 Mustangs Discussions on the latest S197 model Mustangs from Ford.

M90 Spark Plug Gap

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Old Nov 24, 2010 | 05:26 PM
  #1  
VistaGT's Avatar
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Default M90 Spark Plug Gap

Hey,

I just put HT0s in the car gapped at .30

I got them from JDM who claims that gap is good and will work even better when I pulley down.

My question is will this gap work and is it okay to run. Roush said between .32 - .35 but when I asked said .30 would "probably" work. I need a more definitive answer than "probably". Do I need to pull the plugs, buy the tool and regap them or is it okay as is? Car runs OK as is N/A.

The stock Roush M90 blower puts down 5psi of boost.....

Thanks a lot!
Old Nov 25, 2010 | 08:08 AM
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Come on its Thanksgiving I want the opinion of those with blowers
Old Nov 25, 2010 | 09:29 AM
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I used the stock ones (08 newer head) no re-gap required as per Roush...car runs great!
Old Nov 25, 2010 | 09:36 AM
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Vista I'm having similar issues as I right this, my car is at the shop. The stock gap on the HT0's is .045 which is also what Roush recommends. I personally think that is too open for a forced induction car. I gapped mine at .035 but it still was not right, the shop is trying .030 as we speek.

On a side note, once the HT0's are gapped, there is NO going back!!! You would have to buy a new set. Let me know how the .030 gap works, with the holiday I probably won't have my car back until Monday.

Here is the Roush recommendation:

"These ROUSH Performance Colder Plugs are one heat range colder than the stock Mustang plug and are designed specifically to handle the high boost pressure and air flow into the engine. The gap on these plugs is 0.045 inches."

Here is the link:

http://store.roushperformance.com/detail.aspx?ID=479
Old Nov 25, 2010 | 02:47 PM
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^^^Yea i've heard different things on this.....

.45 is stock HT0 gap and on factory Roush cars this is how they come I believe, yet I called Roush and they said .35 MAX. I believe the .30 will work well though I'd like to know for sure.

I've also heard there's not a huge difference between .30 -.35 for FI
Old Nov 25, 2010 | 06:20 PM
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I just installed what roush sent me. I thought the ht0's are pregapped?
Old Nov 25, 2010 | 06:33 PM
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Originally Posted by 808muscle
I just installed what roush sent me. I thought the ht0's are pregapped?
They are, at .045, but mine are "blowing out" at that gap, too wide IMO. It's at the shop as we speak, they are working out the bugs. FI applications for the most part are gapped at .035 or lower (notice I said for the most part, not always).
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