1986 NGK plug type

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Apr 13, 2010 | 03:38 PM

charv66

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1986 NGK plug type

Reputable (until further notice) local parts store sold me eight
NGK UR5/2771 plugs today for my 1986 C4. I got half of them in then I noticed they are somewhat shorter than the ones that were in there already (Autolite 24).

All they had in stock was NGK. Is this the right NGK type?

-Vince

Apr 13, 2010 | 03:55 PM

toptechx6

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From: FL

Here is a link to NGK's website, you can check for yourself.

http://www.ngksparkplugs.com/part_fi...uv/default.asp

Apr 13, 2010 | 04:42 PM

charv66

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Quote:

Originally Posted by toptechx6

Here is a link to NGK's website, you can check for yourself.

http://www.ngksparkplugs.com/part_fi...uv/default.asp

Thanks. Were all 1986 aluminum heads?

Apr 13, 2010 | 05:23 PM

azrocketman

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From: Tucson Arizona

Quote:

Originally Posted by charv66

Thanks. Were all 1986 aluminum heads?

No. All convertibles and late '86 (maybe last 7000 cars) had aluminum heads.

Steve

Apr 13, 2010 | 05:24 PM

toptechx6

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From: FL

Quote:

Originally Posted by charv66

Thanks. Were all 1986 aluminum heads?

The Black Book says all convertibles got aluminum heads and the last 8594 coupes. Easy enough to tell, try a magnet on them.

Apr 13, 2010 | 05:33 PM

azrocketman

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From: Tucson Arizona

Quote:

Originally Posted by toptechx6

The Black Book says all convertibles got aluminum heads and the last 8594 coupes. Easy enough to tell, try a magnet on them.

Even easier to tell (if stock): Iron heads have valve cover bolts on the perimeter and aluminum heads have valve cover bolts down the middle.

Steve

Apr 13, 2010 | 05:36 PM

charv66

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Quote:

Originally Posted by toptechx6

The Black Book says all convertibles got aluminum heads and the last 8594 coupes. Easy enough to tell, try a magnet on them.

They aren't magnetic - thanks for the tip, my VIN is 1G1YY078XG5110177. Would this be considered a late production number?

Apr 13, 2010 | 05:45 PM

samsonb

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Quote:

Originally Posted by charv66

They aren't magnetic - thanks for the tip, my VIN is 1G1YY078XG5110177. Would this be considered a late production number?

Just go look and see if the valve covers have perimeter bolts or center bolts. That will tell you for sure.

Perimeter bolts = Iron heads
Center bolts = Aluminum heads

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Apr 13, 2010 | 05:59 PM

toptechx6

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From: FL

Quote:

Originally Posted by joshwilson3

Just go look and see if the valve covers have perimeter bolts or center bolts. That will tell you for sure.

Perimeter bolts = Iron heads
Center bolts = Aluminum heads

There you go, even easier in case you have bad magnet!

The VIN looks to be an early car, my Black Book shows 35,109 total production, 27, 794 coupes and 7315 ragtops.

Apr 13, 2010 | 06:17 PM

#10

charv66

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Quote:

Originally Posted by toptechx6

There you go, even easier in case you have bad magnet!

The VIN looks to be an early car, my Black Book shows 35,109 total production, 27, 794 coupes and 7315 ragtops.

Ok aluminum it is! No magnetic attraction + has center bolts on the valve covers.

Eight new NGK FR4's going on. They are slightly longer than the old Autolite 24s that were in there but perhaps they were the wrong type to begin with.

Apr 13, 2010 | 06:21 PM

#11

toptechx6

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From: FL

Quote:

Originally Posted by charv66

So much for the accuracy of the Black Book unless a previous owner replaced the heads? Anyway glad you figured out which plugs were correct.

Apr 13, 2010 | 06:23 PM

#12

charv66

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Quote:

Originally Posted by toptechx6

So much for the accuracy of the Black Book unless a previous owner replaced the heads? Anyway glad you figured out which plugs were correct.

I'm always a little nervous putting in longer plugs though!

Apr 13, 2010 | 07:16 PM

#13

toptechx6

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From: FL

My GM parts reference shows the original AC Delco plug to be FR3LS, and according to this crossover chart the FR4's should be correct.

http://www.clubplug.net/cross.html

Apr 13, 2010 | 07:33 PM

#14

charv66

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[QUOTE=toptechx6;1573749490]My GM parts reference shows the original AC Delco plug to be FR3LS, and according to this crossover chart the FR4's should be correct.

http://www.clubplug.net/cross.html[/QUOTE

Thanks everyone.

Apr 13, 2010 | 07:41 PM

#15

Joe C

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for my 90, i presently have ACDelco FR5LS (in the car when i bought it) i have a set of NGK replacements, FR4GP's. the NGK's are slightly longer, but barely noticeable...

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