Spark plug change @ 21k miles
Thread Starter
Safety Car
Joined: May 2000
Posts: 4,828
Likes: 355
From: Albuquerque NM
Spark plug change @ 21k miles
I changed the spark plugs today, had only 21,000 miles but 4 1/2 years use with heads/cam, 6,500 rpm redline, etc. Not too bad to do, try it on a sohc 5.4 with a roots supercharger it you want some fun! 
Food for thought guys: After this few miles the spark gap was 70 thousands on all the plugs.
What's stock? 60 thousands? My last dyno was down 15 sae hp from before, maybe this had something to do with the loss.
If you run your car hard, you might want to check a plug, see where you are gapped, cause it will grow with time.
Food for thought guys: After this few miles the spark gap was 70 thousands on all the plugs.
What's stock? 60 thousands? My last dyno was down 15 sae hp from before, maybe this had something to do with the loss. If you run your car hard, you might want to check a plug, see where you are gapped, cause it will grow with time.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Screw
There is a gap in the Bosh plugs and it can change over time!
Look at the electrode wire and the creamic insulator. Where the wire exits the ceramic insulator center, the wire will eventualy errode down and resess in to the creamic insulator!
Once it does that the plug is shot.
BC
There is a gap in the Bosh plugs and it can change over time!
Look at the electrode wire and the creamic insulator. Where the wire exits the ceramic insulator center, the wire will eventualy errode down and resess in to the creamic insulator!Once it does that the plug is shot.
BC
Race Director
Joined: Sep 2004
Posts: 17,786
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From: Redsox, Pats, Celts & Bruins !!! Redsox Nation !!!
St. Jude Donor '06-'07-'08-'09-'10-'11-'12
And how long does that take? I have never had a problem with the +4s in my last 6 cars. From SC'd BMW to my Vette.
As far as the "gap" I understand what your saying, Thanks
As far as the "gap" I understand what your saying, Thanks
