changing long over due spark plugs

grumpyvette

Administrator
Staff member
rddaves54 said:
I,m Changing spark plugs in 2002 Tahoe, what are the best ones. I Have 238,000 miles and I do not know if even been changed.

ITS extremely important that you ask questions and get accurate answers , BEFORE purchasing headers about what style cylinder heads the headers are designed to fit, below is pictured a set of headers obviously designed for factory strait plug heads but bolted to a set of angle plug heads making spark plug access and wiring a clearance and heat , destroying ignition wire nightmare
p34143a.jpg
p34143b.jpg

angle plug
p34143c.jpg

if you got so much mileage from the last set that you can,t even remember when you bought or installed them Id sure pull one and buy the same ones again, as they obviously last a good long while!
please post pictures once they are out, as clear picture can tell you a good deal about condition of an engine and combustion
(don,t forget anti-seize on the new plug threads, and if the current plugs won,t back out easily try spraying them with a good penetrating oil spray, a couple times and letting the engine sit for a few hours, to soak the threads spray again every 30-60 minutes with a good penetrating oil spray,while you wait as you remember, too to allow the oil to loosen the threads you sure don,t need stripped plug threads, by forcing them. )
index.php


before RE-INSTALLING,
COAT THE SPARK PLUG THREADS,
WITH ANTI-SEIZE PASTE,

as it tends to prevent future problems

antiseize2.jpg

http://garage.grumpysperformance.com/index.php?threads/why-use-anti-seize-paste.9424/#post-39167

http://loctitefreezeandrelease.com/
freezerel.png

http://www.freealloil.com/
TRRBcan.gif

they make adapter crush gaskets

https://www.jegs.com/i/Moroso/710/71900/10002/-1
PlugSeats.jpg

taperseat1.jpg

RELATED INFO

viewtopic.php?f=50&t=9191&p=32959&hilit=pint+spout#p32959
 
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stock plug gap is .060" on that motor, and i second the notion of getting the same model again, spark plugs should be changed atleast every 75k miles in a stock vehicle, mine never last more than a couple oil changes it seems... haha
 
rddaves54 said:
heres the old plugs that have been changed.

oldplugsxcv.jpg

considering the life span they were subjected too,they look to be in remarkably good condition other than what is obviously a rather wide spark gap now
 

Does the increased gap always come from the erosion of the center electrode?

That's the first time I've ever heard of a 7 cylinder engine in a Tahoe !!! :cool:

 
both the insulated tip of the center powered electrode and the curved ground electrode surface tend to erode over time, increasing the effective spark gap,
and I'm fairly sure the picture he posted was cropped before he posted it for some reason eliminating the 8th plug.
if you look at a similar new plug its amazing how little wear there was in 130 k plus miles since his last plug change
acf-41-993_w.jpg


https://www.boltdepot.com/fastener-information/materials-and-grades/Thread-galling.aspx

https://www.fastenal.com/content/feds/pdf/Article - Galling.pdf

antiseize.jpg


http://garage.grumpysperformance.co...-intake-manifold-vs-buy-new.11258/#post-50891

http://garage.grumpysperformance.co...afety-wire-locking-fasteners.4306/#post-48044

http://garage.grumpysperformance.com/index.php?threads/removing-rusted-broken-bolts.807/#post-43180
 
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the stock plug gap for iron block truck LS motors is .060" so thats why the gap looks so wide... because it is. im not sure what the deal is with that but i guess the guys at gm make the big bucks FOR A REASON
 

I don,t know why this is ignored by so many people,
before RE-INSTALLING
, YOUR NEW SPARK PLUGS
COAT THE SPARK PLUG THREADS,
WITH ANTI-SEIZE PASTE,
as it tends to prevent future problems

antiseize2.jpg
b4c4f4424b6fcf47f997346415cfcaee-png.83019

http://garage.grumpysperformance.com/index.php?threads/why-use-anti-seize-paste.9424/#post-39167

be very sure you use anti-seize paste on exhaust manifold stud/bolt threads also or you'll regret not doing so later
med_1602869046-stud.jpeg


I recently had a guy bring a 1989 corvette into the shop, 7 of the 8 spark plugs were,locked solidly in the aluminum heads,
and after he tried to remove and change them,
he found they were locked solidly in the heads ,to the point they were just spinning only with a long breaker bar, and the threads on the plugs were filled with stripped aluminum that used too be threads in the aluminum head castings,
or put a bit differently,there were no longer the spark plug threads,in the heads, as that aluminum was wrapped around the spark plugs that were removed taking the previously machined aluminum threads out of the heads in the process.
the heads were totally stripped, out and the plugs were not going to be removable. this REQUIRES taking the heads off,
and too a machine shop to be re-welded and re-machined in most cases.
this could very easily cost well in excess of $300 and its so easy to prevent.
yes there are over sized steel spark plug thread, replacement thread inserts that can be used in some cases
but even those are best installed correctly with the damaged heads off the engine and work done at a trusted machine shop.
yes there are thread chaser tools
strippedthreadspl2.jpg

weatherstripped.jpg

images

but in many cases the heads are damaged to the point the only really good option is weld up the damage and re-cut new threads

https://www.toolsid.com/gearwrench/gearwrench-spark-plug-thread-inserts-451351991.html

https://www.grainger.com/product/1U...s_kwcid=AL!2966!3!50916716037!!!g!82496523717!
 
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This updated thread has jogged my memory that I need to change the factory plugs on my 2003 Gmc truck! :oops:
It has 168,000 on it.
 
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