Spark Plug Lengths - shorty's - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DKSpringer · 10-30-2018, 11:30 PM

Read lots of conflicting info on forums from past posts, so I thought I would share some details. I have some cheap Chinese headers, and they don't have the best plug clearance. Here is a photo of the different length spark plugs commonly mentioned for small block Chevys. We have:
ACDelco 41-905
Autolite 145
NGK YR5
Champion RV92YC
Accel header plugs 0576S

Accel are the shortest, Champion are not far behind at a lower cost.

Hope this helps someone!

ilnvyb360 · 10-31-2018, 12:55 AM

Thanks for the info!

Axle · 11-04-2018, 11:32 AM

A Denso u11 is just shy of 2.25" from taper to end of plug. Can you measure any one of the ones you got pictured? Just to be able to reference to what the reader has on hand.

Alex.

DKSpringer · 11-04-2018, 12:57 PM

I'm out of town for a while, but here's a thread with some reference.
http://nastyz28.com/threads/spark-plug-length.60539/
I believe the UR5 is the same as my YR5 at 2.072"

Dead Parrot · 11-04-2018, 07:41 PM

Which, if any, fit your header setup?

DKSpringer · 11-04-2018, 10:48 PM

The NGK/Champion fit everywhere but #5. It needed Accel. You can get a pretty good deal on the Accels at Advance Auto with a 25% off deal. I also have the fiberglass spark plug wire protectors.

**Palf70Step** · 11-05-2018, 09:23 AM

I used the accel's on my last 2 trucks with V8s and headers, They made a huge difference in clearance. Neither engine had much mods and they ran very well also for my situation.

**MikeB** · 11-05-2018, 11:07 PM

And here's a picture comparing two non-tapered seat plugs for older heads and aftermarket aluminum heads. Not just shorter, but smaller body diameter and wrench size, too. Great for keeping plug boots away from header tubes. That's an NGK on the left, but Bosch and others also make plugs in that same size (called "ISO").

ilnvyb360 · 11-06-2018, 06:13 PM

Quote:

Originally Posted by MikeB

And here's a picture comparing two non-tapered seat plugs for older heads and aftermarket aluminum heads. Not just shorter, but smaller body diameter and wrench size, too. Great for keeping plug boots away from header tubes. That's an NGK on the left, but Bosch and others also make plugs in that same size (called "ISO").

MikeB,
Can you share the NGK part number? I’m seeing BKR5 and an 11 under that but can’t make out the rest.

Thanks!
B

**MikeB** · 11-06-2018, 06:32 PM

They are BKR5ES

B = 14mm thread
K = hex size 5/8"
R = resistor
5 = heat range (comparable to AC 44 or 45, as I recall)
ES = standard 3/4" reach

Got them 10-12 years ago, so their part number scheme may have changed since then.

I have an NGK chart that shows "11" means the gap is 1.1 mm or .044". I guess that refers to the out of box gap.

ilnvyb360 · 11-06-2018, 07:52 PM

Great info! Thanks MikeB!!

**MikeB** · 11-07-2018, 10:48 AM

Here's a link to the NGK chart:
https://rb30det.com/wp-content/uploa...7/ngkchart.jpg

10-30-2018, 11:30 PM	#1
DKSpringer Registered User Join Date: Nov 2014 Location: Cedar Falls, IA Posts: 49	Spark Plug Lengths - shorty's Read lots of conflicting info on forums from past posts, so I thought I would share some details. I have some cheap Chinese headers, and they don't have the best plug clearance. Here is a photo of the different length spark plugs commonly mentioned for small block Chevys. We have: ACDelco 41-905 Autolite 145 NGK YR5 Champion RV92YC Accel header plugs 0576S Accel are the shortest, Champion are not far behind at a lower cost. Hope this helps someone! Attached Images

10-31-2018, 12:55 AM	#2
ilnvyb360 Registered User Join Date: Mar 2018 Location: Whidbey Island, WA Posts: 49	Re: Spark Plug Lengths - shorty's Thanks for the info! Last edited by ilnvyb360; 10-31-2018 at 12:55 AM. Reason: Delete emoji

11-04-2018, 11:32 AM	#3
Axle Registered User Join Date: Jul 2011 Location: SW Ontario Posts: 1,214	Re: Spark Plug Lengths - shorty's A Denso u11 is just shy of 2.25" from taper to end of plug. Can you measure any one of the ones you got pictured? Just to be able to reference to what the reader has on hand. Alex.

11-04-2018, 12:57 PM	#4
DKSpringer Registered User Join Date: Nov 2014 Location: Cedar Falls, IA Posts: 49	Re: Spark Plug Lengths - shorty's I'm out of town for a while, but here's a thread with some reference. http://nastyz28.com/threads/spark-plug-length.60539/ I believe the UR5 is the same as my YR5 at 2.072"

11-04-2018, 10:48 PM	#6
DKSpringer Registered User Join Date: Nov 2014 Location: Cedar Falls, IA Posts: 49	Re: Spark Plug Lengths - shorty's The NGK/Champion fit everywhere but #5. It needed Accel. You can get a pretty good deal on the Accels at Advance Auto with a 25% off deal. I also have the fiberglass spark plug wire protectors. Attached Images

11-04-2018, 07:41 PM	#5
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,630	Re: Spark Plug Lengths - shorty's Which, if any, fit your header setup?

11-05-2018, 09:23 AM	#7
Palf70Step State of Confusion! Join Date: Jul 2002 Location: Gulfport, MS USA Posts: 47,271	Re: Spark Plug Lengths - shorty's I used the accel's on my last 2 trucks with V8s and headers, They made a huge difference in clearance. Neither engine had much mods and they ran very well also for my situation. __________________ Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God!

11-05-2018, 11:07 PM	#8
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,612	Re: Spark Plug Lengths - shorty's And here's a picture comparing two non-tapered seat plugs for older heads and aftermarket aluminum heads. Not just shorter, but smaller body diameter and wrench size, too. Great for keeping plug boots away from header tubes. That's an NGK on the left, but Bosch and others also make plugs in that same size (called "ISO"). __________________ Mike 1969 C10 LWB -- owned for 36 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

11-06-2018, 06:32 PM	#10
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,612	Re: Spark Plug Lengths - shorty's They are BKR5ES B = 14mm thread K = hex size 5/8" R = resistor 5 = heat range (comparable to AC 44 or 45, as I recall) ES = standard 3/4" reach Got them 10-12 years ago, so their part number scheme may have changed since then. I have an NGK chart that shows "11" means the gap is 1.1 mm or .044". I guess that refers to the out of box gap. __________________ Mike 1969 C10 LWB -- owned for 36 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

11-06-2018, 07:52 PM	#11
ilnvyb360 Registered User Join Date: Mar 2018 Location: Whidbey Island, WA Posts: 49	Re: Spark Plug Lengths - shorty's Great info! Thanks MikeB!!

11-07-2018, 10:48 AM	#12
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,612	Re: Spark Plug Lengths - shorty's Here's a link to the NGK chart: https://rb30det.com/wp-content/uploa...7/ngkchart.jpg __________________ Mike 1969 C10 LWB -- owned for 36 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

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