Plug requirements for 383 stroker/same as 350? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Sport/Truck · 09-27-2008, 06:04 PM

I'm wondering if a 383 uses the same spark plugs (heat range) as the 350.
I'm also using an HEI too. What gap should I use?

s/t

Arad68 · 09-27-2008, 06:21 PM

Spark plug requirements are based on numerous things, but the two most important are compression (compression will determine heat range) and reach. Here is a quick guide that I use and a website that is very useful.

http://www.sparkplugs.com/

Here are the recommendations from edelbrock. I believe the plug seats are flat, so you should use the washers (if they are tapered seats, you don't use the washer...)

Under 9.5 to 1 Compression

Champion ---------- RC12YC / 2071
NGK --------------- FR 4 / 5155 OR BCPR5ES / 6130
Autolite ------------ 3926
Motorcraft --------- AGSFP52
Accel Shorty ------- 0416S

Up to 10.5 to 1 Compression

Champion ----------- RC9YC / 2075
Autolite -------------- 3924
NGK ----------------- FR 5 / 7373 OR BCPR7ES / 3330
Accel Shorty -------- 0414S

11 to 1 Compression

Champion ------------ C63YC / 796
NGK ------------------ R5672A-8 / 7173

12 to 1 Compression

Champion ------------- C61YC / 785
NGK ------------------- R5672A-9 / 7405

"Reach" is where the electrode and grounding strap are placed in the combustion chamber. It is the length of the threaded end of the spark plug.
What kind of heads do you have?

Sport/Truck · 09-27-2008, 06:39 PM

Thanks for the info.
I have NGK 7052 / YR5 v-power. I'm not sure where they fit in your compression chart....I'm at about 10:1 compression.
s/t

Arad68 · 09-27-2008, 06:50 PM

Go to www.sparkplugs.com. At the bottom of the page is a link called sparkplug 411. Go to the bottom of this page and you will find a numbering system for NGK

Sport/Truck · 09-27-2008, 11:40 PM

OK, thanks, looks like I'm right in the ball park with the heat range.
What gap should I set these at since I'm using HEI? They come factory set at .039.
s/t

Arad68 · 09-28-2008, 12:54 AM

.039 is good. Larger gap tends to dissipate
or diminish the spark. No more than .045

Sport/Truck · 09-28-2008, 10:28 AM

Thanks Don....I'll get these put in today!
s/t

Sport/Truck · 09-28-2008, 10:28 AM

Thanks Don....I'll get these put in today!
s/t

09-27-2008, 06:04 PM	#1
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Plug requirements for 383 stroker/same as 350? I'm wondering if a 383 uses the same spark plugs (heat range) as the 350. I'm also using an HEI too. What gap should I use? s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

09-27-2008, 06:21 PM	#2
Arad68 Trucks N Tranzams Join Date: Dec 2002 Location: North Las Vegas, Nevada Posts: 816	Re: Plug requirements for 383 stroker/same as 350? Spark plug requirements are based on numerous things, but the two most important are compression (compression will determine heat range) and reach. Here is a quick guide that I use and a website that is very useful. http://www.sparkplugs.com/ Here are the recommendations from edelbrock. I believe the plug seats are flat, so you should use the washers (if they are tapered seats, you don't use the washer...) Under 9.5 to 1 Compression Champion ---------- RC12YC / 2071 NGK --------------- FR 4 / 5155 OR BCPR5ES / 6130 Autolite ------------ 3926 Motorcraft --------- AGSFP52 Accel Shorty ------- 0416S Up to 10.5 to 1 Compression Champion ----------- RC9YC / 2075 Autolite -------------- 3924 NGK ----------------- FR 5 / 7373 OR BCPR7ES / 3330 Accel Shorty -------- 0414S 11 to 1 Compression Champion ------------ C63YC / 796 NGK ------------------ R5672A-8 / 7173 12 to 1 Compression Champion ------------- C61YC / 785 NGK ------------------- R5672A-9 / 7405 "Reach" is where the electrode and grounding strap are placed in the combustion chamber. It is the length of the threaded end of the spark plug. What kind of heads do you have? __________________ Don '68 Chevy LB 383 TH400/GV/373 posi '56 Chevy 4WD SWB '64 Chevy short stepside '79 Trans Am 455/TH2004R/12blt/4whldisc 95 Kia (Wifes car) 2002 S-10 extended cab pickup "God punishes small sins immediately"

09-27-2008, 06:39 PM	#3
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Plug requirements for 383 stroker/same as 350? Thanks for the info. I have NGK 7052 / YR5 v-power. I'm not sure where they fit in your compression chart....I'm at about 10:1 compression. s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe. Last edited by Sport/Truck; 09-27-2008 at 06:40 PM.

09-27-2008, 06:50 PM	#4
Arad68 Trucks N Tranzams Join Date: Dec 2002 Location: North Las Vegas, Nevada Posts: 816	Re: Plug requirements for 383 stroker/same as 350? Go to www.sparkplugs.com. At the bottom of the page is a link called sparkplug 411. Go to the bottom of this page and you will find a numbering system for NGK __________________ Don '68 Chevy LB 383 TH400/GV/373 posi '56 Chevy 4WD SWB '64 Chevy short stepside '79 Trans Am 455/TH2004R/12blt/4whldisc 95 Kia (Wifes car) 2002 S-10 extended cab pickup "God punishes small sins immediately"

09-27-2008, 11:40 PM	#5
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Plug requirements for 383 stroker/same as 350? OK, thanks, looks like I'm right in the ball park with the heat range. What gap should I set these at since I'm using HEI? They come factory set at .039. s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe. Last edited by Sport/Truck; 09-27-2008 at 11:42 PM.

09-28-2008, 12:54 AM	#6
Arad68 Trucks N Tranzams Join Date: Dec 2002 Location: North Las Vegas, Nevada Posts: 816	Re: Plug requirements for 383 stroker/same as 350? .039 is good. Larger gap tends to dissipate or diminish the spark. No more than .045 __________________ Don '68 Chevy LB 383 TH400/GV/373 posi '56 Chevy 4WD SWB '64 Chevy short stepside '79 Trans Am 455/TH2004R/12blt/4whldisc 95 Kia (Wifes car) 2002 S-10 extended cab pickup "God punishes small sins immediately" Last edited by Arad68; 09-28-2008 at 12:55 AM.

09-28-2008, 10:28 AM	#7
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Plug requirements for 383 stroker/same as 350? Thanks Don....I'll get these put in today! s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.



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