Spark Plug Gap - ZR-1 Net Registry Forums

ZR-FUN · 09-30-2008

OE gap is 0.05. I'm wondering what the best gap for a stock ZR-1 ('90) w/ NGK iridiums is... I hear a lot of different opinions from the GM for plugs...

Edit: Maybe this should be in the tech section.

tomtom72 · 09-30-2008

I don't know that this will help as I use the stock GM replacement plugs, the 402's, in my '90, but I use 35 as my gap as per the FSM.

jonszr1 · 09-30-2008

first off be very carefull when cking the gap on these plugs . i use a ring gap tool and go until it just bearly touches . i found with these plugs that 45 thou is max for me .i settled on 40 thou for the ngk. hope this helps

ZR-FUN · 09-30-2008

OE specwas 0.05. then they said use 0.035 as your doing. for the rapid fires they said 0.045. so its confusing.

But, NGK's come at different factory gap. And a different gap for each type of plug they make for the LT-5. so i was wondering what was best for the NGK iridiums.

So, 0.04 for the NGK iridium?

jonszr1 · 09-30-2008

yes ,being an old drag racer i have gotten used to reading plugs and at .40thou. they seem to burn the cleanest . jmho

karterdon · 09-30-2008

keep in mind that you do not have a high performance ignition system - So your coils can only produce so much voltage to jump the GAP - the bigger the gap the more umpf you need - So I would stay between the .035 - .040 gap. The plug is not the issue - Its the ignition system we have.

Don Yoakem
91 - #267
Dark Red Met.

jonszr1 · 10-01-2008

i agree . its the coils that limit the gap

Pete · 10-01-2008

1990 has .035 from the factory.
I wouldn't go more then that with stock ignition..

Pete

jonszr1 · 10-01-2008

pete , just wondering why is the 90 different than the other years ?

Pete · 10-02-2008

Quote:

Originally Posted by jonszr1

pete , just wondering why is the 90 different than the other years ?

It's 1990-1992 have .035 factory specs.
1993-1995 are .050 factory specs.

I think for idle quality and they went with those 100,000 mile spark plugs,not 100% sure.
Pete

09-30-2008	#1
ZR-FUN Join Date: Sep 2008 Location: Toronto, Ontario Posts: 7	Spark Plug Gap OE gap is 0.05. I'm wondering what the best gap for a stock ZR-1 ('90) w/ NGK iridiums is... I hear a lot of different opinions from the GM for plugs... Edit: Maybe this should be in the tech section.

09-30-2008	#3
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: Spark Plug Gap first off be very carefull when cking the gap on these plugs . i use a ring gap tool and go until it just bearly touches . i found with these plugs that 45 thou is max for me .i settled on 40 thou for the ngk. hope this helps

09-30-2008	#4
ZR-FUN Join Date: Sep 2008 Location: Toronto, Ontario Posts: 7	Re: Spark Plug Gap OE specwas 0.05. then they said use 0.035 as your doing. for the rapid fires they said 0.045. so its confusing. But, NGK's come at different factory gap. And a different gap for each type of plug they make for the LT-5. so i was wondering what was best for the NGK iridiums. So, 0.04 for the NGK iridium?

09-30-2008	#5
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: Spark Plug Gap yes ,being an old drag racer i have gotten used to reading plugs and at .40thou. they seem to burn the cleanest . jmho

09-30-2008	#6
karterdon Join Date: Jan 2008 Location: Antioch, Illinois Posts: 129	Re: Spark Plug Gap keep in mind that you do not have a high performance ignition system - So your coils can only produce so much voltage to jump the GAP - the bigger the gap the more umpf you need - So I would stay between the .035 - .040 gap. The plug is not the issue - Its the ignition system we have. Don Yoakem 91 - #267 Dark Red Met.

09-30-2008	#2
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Spark Plug Gap I don't know that this will help as I use the stock GM replacement plugs, the 402's, in my '90, but I use 35 as my gap as per the FSM. __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

10-01-2008	#7
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: Spark Plug Gap i agree . its the coils that limit the gap

10-01-2008	#8
Pete Join Date: Dec 2003 Location: Chicagoland,IL Posts: 2,679	Re: Spark Plug Gap 1990 has .035 from the factory. I wouldn't go more then that with stock ignition.. Pete __________________ '91 #1635 PoloGreen 350 LT5 11.09 @ 129.27 11.04 @ 128.86 474RWHP 400RWTQ http://www.youtube.com/watch?v=SFNFOhGGlR4 http://www.youtube.com/watch?v=ZlRIOMwaDYY https://sites.google.com/site/peteszr1garage

10-01-2008	#9
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,407	Re: Spark Plug Gap pete , just wondering why is the 90 different than the other years ?