74 BB Spark plug confusion
Thread Starter
Instructor
Joined: Dec 2024
Posts: 123
Likes: 28
From: Chicago Burbs
74 BB Spark plug confusion
Spark Plug Reach confusion.
Currently i Have AC R45TS Heat Range 5 / Reach 0.370"
Recommended Plug AC R43TS Heat Range 3 / Reach 0.431"
I went with a hotter plug since most of driving is around town & thought that would be better - What I didn't notice until today was the difference in Reach???
The R45's plugs didn't look all that great when i pulled them out and it was difficult to get the wires seated until i hear a click.
Therefore, thinking about changing brands to NGK
Cross reference Shows
NGK YR5 Heat Range 5 / Reach 0.460"
My understanding of proper reach is you want the insulator and electrode along with the ground to just enter the combustion chamber - why would three different recommended plugs have different reaches??? Makes no sense to me. Obviously to long a reach could be tragic.
Final Q what is the proper reach for a 1974 454?
Currently i Have AC R45TS Heat Range 5 / Reach 0.370"
Recommended Plug AC R43TS Heat Range 3 / Reach 0.431"
I went with a hotter plug since most of driving is around town & thought that would be better - What I didn't notice until today was the difference in Reach???
The R45's plugs didn't look all that great when i pulled them out and it was difficult to get the wires seated until i hear a click.
Therefore, thinking about changing brands to NGK
Cross reference Shows
NGK YR5 Heat Range 5 / Reach 0.460"
My understanding of proper reach is you want the insulator and electrode along with the ground to just enter the combustion chamber - why would three different recommended plugs have different reaches??? Makes no sense to me. Obviously to long a reach could be tragic.
Final Q what is the proper reach for a 1974 454?
Thread Starter
Instructor
Joined: Dec 2024
Posts: 123
Likes: 28
From: Chicago Burbs
Thanks Guys,
Not sure where I got the info on the R43 plug was standard. the current plugs - R45 reach at 0.37 could possibly be why I'm seeing fouled plugs when I have the Carb / Timing set properly.
Looking up the R44TS the reach shown on Summits Website shows 0.430" reach.
Thinking about returning the NGK's as i wanted a hotter plug for the driving I do.
What plugs are other's using in their 454's??
Also recommended gap for Points if any can recommend
Not sure where I got the info on the R43 plug was standard. the current plugs - R45 reach at 0.37 could possibly be why I'm seeing fouled plugs when I have the Carb / Timing set properly.
Looking up the R44TS the reach shown on Summits Website shows 0.430" reach.
Thinking about returning the NGK's as i wanted a hotter plug for the driving I do.
What plugs are other's using in their 454's??
Also recommended gap for Points if any can recommend
Last edited by Dream Car C3; Nov 12, 2025 at 09:28 AM. Reason: Add note
Race Director
Joined: May 2006
Posts: 18,734
Likes: 2,582
Thanks Guys,
Not sure where I got the info on the R43 plug was standard. the current plugs - R45 reach at 0.37 could possibly be why I'm seeing fouled plugs when I have the Carb / Timing set properly.
Looking up the R44TS the reach shown on Summits Website shows 0.430" reach.
Thinking about returning the NGK's as i wanted a hotter plug for the driving I do.
What plugs are other's using in their 454's??
Also recommended gap for Points if any can recommend
Not sure where I got the info on the R43 plug was standard. the current plugs - R45 reach at 0.37 could possibly be why I'm seeing fouled plugs when I have the Carb / Timing set properly.
Looking up the R44TS the reach shown on Summits Website shows 0.430" reach.
Thinking about returning the NGK's as i wanted a hotter plug for the driving I do.
What plugs are other's using in their 454's??
Also recommended gap for Points if any can recommend
Thread Starter
Instructor
Joined: Dec 2024
Posts: 123
Likes: 28
From: Chicago Burbs
I was referring to the Plug Gap - Originally found it at 0.032 - 0.035 for use with points distributor.
I'm pretty much having to start over on my Tune Setup since I got a ton of water in the tank.
I'm sure i have a fouled sock so I'm installing a new sending unit Friday - hopefully this solves my fuel pressure issues - since i cant keep the engine running for longer than 30 seconds or so once i manually fill the bowl and runs dry.
The original plugs R45TS were either fouled by the water or bad setup? Original setup - I did set the dwell at 30, and the initial timing at 6-8 deg BTDC ...I just bought a new timing light with dial so i can check total timing - I was going to start with 32 deg total timing.
I've been chasing down rabbit holes with ignition when it really was water in the gas tank.
I'm pretty much having to start over on my Tune Setup since I got a ton of water in the tank.
I'm sure i have a fouled sock so I'm installing a new sending unit Friday - hopefully this solves my fuel pressure issues - since i cant keep the engine running for longer than 30 seconds or so once i manually fill the bowl and runs dry.
The original plugs R45TS were either fouled by the water or bad setup? Original setup - I did set the dwell at 30, and the initial timing at 6-8 deg BTDC ...I just bought a new timing light with dial so i can check total timing - I was going to start with 32 deg total timing.
I've been chasing down rabbit holes with ignition when it really was water in the gas tank.
Race Director
Joined: May 2006
Posts: 18,734
Likes: 2,582
I was referring to the Plug Gap - Originally found it at 0.032 - 0.035 for use with points distributor.
I'm pretty much having to start over on my Tune Setup since I got a ton of water in the tank.
I'm sure i have a fouled sock so I'm installing a new sending unit Friday - hopefully this solves my fuel pressure issues - since i cant keep the engine running for longer than 30 seconds or so once i manually fill the bowl and runs dry.
The original plugs R45TS were either fouled by the water or bad setup? Original setup - I did set the dwell at 30, and the initial timing at 6-8 deg BTDC ...I just bought a new timing light with dial so i can check total timing - I was going to start with 32 deg total timing.
I've been chasing down rabbit holes with ignition when it really was water in the gas tank.
I'm pretty much having to start over on my Tune Setup since I got a ton of water in the tank.
I'm sure i have a fouled sock so I'm installing a new sending unit Friday - hopefully this solves my fuel pressure issues - since i cant keep the engine running for longer than 30 seconds or so once i manually fill the bowl and runs dry.
The original plugs R45TS were either fouled by the water or bad setup? Original setup - I did set the dwell at 30, and the initial timing at 6-8 deg BTDC ...I just bought a new timing light with dial so i can check total timing - I was going to start with 32 deg total timing.
I've been chasing down rabbit holes with ignition when it really was water in the gas tank.
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Thread Starter
Instructor
Joined: Dec 2024
Posts: 123
Likes: 28
From: Chicago Burbs
Thanks,
Appreciate the info.
Basically i'm starting over.
New Plugs, have a new set of Taylor Wires I never put on....going to leave them long enough so when i switch over to MSD i can redo the Dizzy terminal ends.
My immediate issue - need to get this running good enough and confidently enough so i can move it, to my other storage site for long term repair.
I did order the Mr gasket spring kit...cheap enough.
Not sure if any others my feel the same.....and it certainly makes zero sense.
"The more I learn the less I understand"
Appreciate the info.
Basically i'm starting over.
New Plugs, have a new set of Taylor Wires I never put on....going to leave them long enough so when i switch over to MSD i can redo the Dizzy terminal ends.
My immediate issue - need to get this running good enough and confidently enough so i can move it, to my other storage site for long term repair.
I did order the Mr gasket spring kit...cheap enough.
Not sure if any others my feel the same.....and it certainly makes zero sense.
"The more I learn the less I understand"
Race Director
Joined: Jan 2000
Posts: 13,018
Likes: 2,262
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
For the street....even in my 555" engine when it was N/A (before turbos) I always liked running an extended tip plug and as hot as I could find. Never had an issue with it on the street or track or dyno....though race folks would look at me like I was crazy. I don't remember the number off hand...and my heads are different than yours...but AC's did fine. Ran 9's@142 with those plugs and I never had to change them. They just worked.
I run NGK's these days with boost.
And I agree...a low compression big block will like LOTS of timing. I prefer to limit the total advance to end up with that 38-40* or so...but also crank up the initial into the 20's. Have to work on the limit slot and/or bushing...but it will really wake things up.
JIM
I run NGK's these days with boost.
And I agree...a low compression big block will like LOTS of timing. I prefer to limit the total advance to end up with that 38-40* or so...but also crank up the initial into the 20's. Have to work on the limit slot and/or bushing...but it will really wake things up.
JIM
