BB plugs
Thread Starter
Instructor
Joined: Aug 2016
Posts: 172
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BB plugs
Hi all,
Woe and confusion here..
I read somewhere that post 1970 big blocks take tapered plugs... so i bought a set of Autolite 145's for my 454, which is wearing a set of '72 LS6 open chamber rectanguar port heads.
I pulled a plug last night... to find a) the plug isnt tapered... and b) it's a .690 inch plug; vs the .460 plug that i bought.
Question is... have i bought the wrong plug... or does it have the wrong plug in it?
Many thanks for thoughts.
David
Woe and confusion here..
I read somewhere that post 1970 big blocks take tapered plugs... so i bought a set of Autolite 145's for my 454, which is wearing a set of '72 LS6 open chamber rectanguar port heads.
I pulled a plug last night... to find a) the plug isnt tapered... and b) it's a .690 inch plug; vs the .460 plug that i bought.
Question is... have i bought the wrong plug... or does it have the wrong plug in it?
Many thanks for thoughts.
David
Race Director
Joined: May 2006
Posts: 18,668
Likes: 2,564
1. It appears based on your description by year the wrong plug is currently in the engine.
2. Can you see the spark plug seat in the head and confirm it is tapered versus flat.
3. How did you end up with Autolite 145 as the correct plug. The Autolite site and vendor sites do not list that number for a 72 454.
http://www.jegs.com/webapp/wcs/store...ear=4294829731
2. Can you see the spark plug seat in the head and confirm it is tapered versus flat.
3. How did you end up with Autolite 145 as the correct plug. The Autolite site and vendor sites do not list that number for a 72 454.
http://www.jegs.com/webapp/wcs/store...ear=4294829731
Race Director
Joined: Oct 2000
Posts: 12,642
Likes: 3,103
From: Shamong, NJ
I think the original plugs were either AC Delco R43's or R44's, with R45, R43S, R44S and R45S also recommended, depending on usage (city, highway, etc). None of these are tapered plugs, that I know of.
The current replacement conventional plugs, recommended by Delco are CR43TS & R43XL, and the platinum equivalent is the 41-803. Delco has various other 44 and 45 heat range plugs available too.
A quick look at Autolite's website, shows that their 24 & 25 plugs, are the replacements for R43TS, and AP24 & AP25 as the platinum replacements.
The current replacement conventional plugs, recommended by Delco are CR43TS & R43XL, and the platinum equivalent is the 41-803. Delco has various other 44 and 45 heat range plugs available too.
A quick look at Autolite's website, shows that their 24 & 25 plugs, are the replacements for R43TS, and AP24 & AP25 as the platinum replacements.
Thread Starter
Instructor
Joined: Aug 2016
Posts: 172
Likes: 2
1. It appears based on your description by year the wrong plug is currently in the engine.
2. Can you see the spark plug seat in the head and confirm it is tapered versus flat.
3. How did you end up with Autolite 145 as the correct plug. The Autolite site and vendor sites do not list that number for a 72 454.
http://www.jegs.com/webapp/wcs/store...ear=4294829731
2. Can you see the spark plug seat in the head and confirm it is tapered versus flat.
3. How did you end up with Autolite 145 as the correct plug. The Autolite site and vendor sites do not list that number for a 72 454.
http://www.jegs.com/webapp/wcs/store...ear=4294829731
Bought over the counter from someone who told me they'd be fine in a 454...
I've just looked - and yes - they will be fine in a 454 - even a '72 one... as long as it's a truck or a bus; either of which presumably have a peanut port head...
so.. in conclusion - probably both sets are wrong... will try to confirm by inspecting the seat when i get home.
Instructor
Joined: Nov 2013
Posts: 128
Likes: 29
From: Bloomfield Township Michigan
Hi all,
Woe and confusion here..
I read somewhere that post 1970 big blocks take tapered plugs... so i bought a set of Autolite 145's for my 454, which is wearing a set of '72 LS6 open chamber rectanguar port heads.
I pulled a plug last night... to find a) the plug isnt tapered... and b) it's a .690 inch plug; vs the .460 plug that i bought.
Question is... have i bought the wrong plug... or does it have the wrong plug in it?
Many thanks for thoughts.
David
Woe and confusion here..
I read somewhere that post 1970 big blocks take tapered plugs... so i bought a set of Autolite 145's for my 454, which is wearing a set of '72 LS6 open chamber rectanguar port heads.
I pulled a plug last night... to find a) the plug isnt tapered... and b) it's a .690 inch plug; vs the .460 plug that i bought.
Question is... have i bought the wrong plug... or does it have the wrong plug in it?
Many thanks for thoughts.
David
Jeff
Race Director
Joined: May 2006
Posts: 18,668
Likes: 2,564
145 versus 26
Bought over the counter from someone who told me they'd be fine in a 454...
I've just looked - and yes - they will be fine in a 454 - even a '72 one... as long as it's a truck or a bus; either of which presumably have a peanut port head...
so.. in conclusion - probably both sets are wrong... will try to confirm by inspecting the seat when i get home.
I've just looked - and yes - they will be fine in a 454 - even a '72 one... as long as it's a truck or a bus; either of which presumably have a peanut port head...
so.. in conclusion - probably both sets are wrong... will try to confirm by inspecting the seat when i get home.
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Race Director
Joined: May 2006
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I thought you were going to look at the spark plug seat to see if it is tapered or flat? The head casting calls for the Autolite 26 plug or the AC Delco R45TS
Last edited by MelWff; Mar 31, 2017 at 05:27 PM.
Thread Starter
Instructor
Joined: Aug 2016
Posts: 172
Likes: 2
Thanks for that... is there an online reference by casting number that you can share so as to save me getting into a pickle on this stuff in future?
Btw... I'm running hei.... thoughts as to whether the oem plug is still the best option?
(Actually - I've just looked up the plug and it's original fitment - it went into loads of hei equipped cars so that isn't a question now....)
But. What is a question is compression.. this plug was used in low compression applications, and I saw a debate suggesting that it would promote detonation in higher compression motors.. my motor 'just about' runs on premium pump fuel.. but diesels badly on regular... was told when I bought it that it was about 10.25 compression but don't know that for a fact a small I havnt had it apart... do any other plugs have comparable fitment but are more suited to higher compression?
Last edited by Dave Vincec; Apr 1, 2017 at 03:14 AM.
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the only thing that would change with higher compression is the heat range of the plug. Even with that it may vary with the kind of driving you do as to whether a colder plug can be tolerated without fouling. In AC Delco with a high compression engine and driving that does not involve a lot of stop and go I would go with the R44TS which would be in Autolite a 25.