R44 or R45S plugs?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**BanjoDude** · 04-28-2023, 09:59 AM

Hi guys! My manual recommends R44 plugs for the 307 in my 69 C20. I'm running stock ignition with points. The parts store sold me R45S plugs for it. Is there any issue with that, or should I go back and get the 44? Thanks so much as always for your help!

Wes

duallyjams · 04-28-2023, 10:11 AM

The R45s is a hotter plug. My 327 burns oil so I changed from the R44 to the R45s to help from fouling the plugs.

**kwmech** · 04-28-2023, 11:14 AM

It is hotter (as mentioned) and also comes with an extended tip ( S designation). What do the old ones look like? With todays crummy fuel I'd say stick with the 45s

**67 twins** · 04-28-2023, 11:43 AM

That's what I'm running in my 283

**BanjoDude** · 04-28-2023, 12:06 PM

Quote:

Originally Posted by kwmech

It is hotter (as mentioned) and also comes with an extended tip ( S designation). What do the old ones look like? With todays crummy fuel I'd say stick with the 45s

I plan to pull them tonight and have a look at them. I have no idea what's in there and how old they are.

**Wrenchbender Ret** · 04-28-2023, 12:13 PM

The extended tip plug came out in the late 50's early 60's for o-head valve engines. All the manufactures soon went with them. They are a big improvement from the recessed tip plugs. The R45S plug is only one step hotter then the R44. That is the best way to go. They should not be used in flathead engines.

George

697498chevy · 04-28-2023, 12:30 PM

Just checked and I put Autolite 85 plugs in my '69 307 last time . Was that a bad choice ? Seems to run ok . Thanks !

kaycee · 04-28-2023, 02:47 PM

Quote:

Originally Posted by 697498chevy

Just checked and I put Autolite 85 plugs in my '69 307 last time . Was that a bad choice ? Seems to run ok . Thanks !

I used those in my 350 and they were good plugs ,I may switch back next time in my 327,Im running the 44 in them now.

**Ironangel** · 04-28-2023, 02:51 PM

The R45S's should be fine in the 69 307 heads. The older motors tend to lose compression and use a little more oil so going one number hotter is probably a good move. I run the same plug in my 427 BBC w/69 closed chamber heads...I found some ACDelco R45S plugs on ebay for a $1 a piece. They were NOS plugs made in the US, they're not anymore. Hard to find US made spark plugs these days and when you do find them they're hot cheap! I'm running Pulstar plugs in my bike... http://toms427impala.info/CT/ACPlugI...Extended%20Tip

**BanjoDude** · 04-28-2023, 03:45 PM

Quote:

Originally Posted by Ironangel

The R45S's should be fine in the 69 307 heads. The older motors tend to lose compression and use a little more oil so going one number hotter is probably a good move. I run the same plug in my 427 BBC w/69 closed chamber heads...I found some ACDelco R45S plugs on ebay for a $1 a piece. They were NOS plugs made in the US, they're not anymore. Hard to find US made spark plugs these days and when you do find them they're hot cheap! I'm running Pulstar plugs in my bike... http://toms427impala.info/CT/ACPlugI...Extended%20Tip

Interesting. Two of the plugs I got are made in the USA, two made in Mexico, and four made in China. Should I take them back and at least get all 8 from the same plant? If there's a significant variance, it seems like that could have a couple of cylinders running hotter than the others...

697498chevy · 04-28-2023, 04:25 PM

Thanks , Kaycee !!

**BanjoDude** · 04-28-2023, 09:17 PM

Quote:

Originally Posted by BanjoDude

Interesting. Two of the plugs I got are made in the USA, two made in Mexico, and four made in China. Should I take them back and at least get all 8 from the same plant? If there's a significant variance, it seems like that could have a couple of cylinders running hotter than the others...

Anyone have thoughts on mixing and matching the same model plug from different eras/plants? Seems like it would essentially be the same as mixing the same plug from different brands, which I know is not a good idea. Perhaps I should return them and buy a set of NOS off ebay?

**Steeveedee** · 04-28-2023, 09:45 PM

Pretty sure that the product manufactured on different continents is going to be different. Might have not been the case in years past, but now, who knows?

PbFut · 04-28-2023, 10:32 PM

I doubt the difference in manufacturing plant will make such a difference as to be worried. You are going to have a bigger variance in cylinder compression and oil consumption and old plug wire in each hole than you are spark plug difference.
The plugs are not likely going to affect a 100 mile plug read. I would use what you got. Look them over at 100 miles and go from there.

**Ironangel** · 04-28-2023, 11:52 PM

Quote:

Originally Posted by BanjoDude

Anyone have thoughts on mixing and matching the same model plug from different eras/plants? Seems like it would essentially be the same as mixing the same plug from different brands, which I know is not a good idea. Perhaps I should return them and buy a set of NOS off ebay?

I bought him out, he only had 26, I just tuned up the fleet...

Different plugs wont hurt a thing. These late model electronic dudes have O2 sensors on every head pipe can probably see the difference, maybe? That charge and piston dont know what brand just set the fire...

04-28-2023, 09:59 AM	#1
BanjoDude Junior Member Join Date: Feb 2023 Location: Fletcher, OH Posts: 71	R44 or R45S plugs?? Hi guys! My manual recommends R44 plugs for the 307 in my 69 C20. I'm running stock ignition with points. The parts store sold me R45S plugs for it. Is there any issue with that, or should I go back and get the 44? Thanks so much as always for your help! Wes __________________ Found Grandpa's old '69 Chevy C-20 - It'll never leave the family again. "For just a little more, you can do it yourself!"

04-28-2023, 10:11 AM	#2
duallyjams Registered User Join Date: May 2007 Location: Deale Md Posts: 4,663	Re: R44 or R45S plugs?? The R45s is a hotter plug. My 327 burns oil so I changed from the R44 to the R45s to help from fouling the plugs. __________________ James 63 GMC V6 4speed carryall 65 chevy swb bbw V8 auto 68 K20 327/4 speed, buddy buckets 2002 GMC CC Dually Duramax 64 GMC lwb 3/4 V6 4speed SOLD 66 GMC swb bbw buddy buckets SOLD IG duallyjams The only thing that stays the same is constant change!

04-28-2023, 11:14 AM	#3
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,393	Re: R44 or R45S plugs?? It is hotter (as mentioned) and also comes with an extended tip ( S designation). What do the old ones look like? With todays crummy fuel I'd say stick with the 45s

04-28-2023, 11:43 AM	#4
67 twins Senior Member Join Date: Mar 2019 Location: Herculaneum MO (20 minutes south of St. Louis Posts: 588	Re: R44 or R45S plugs?? That's what I'm running in my 283 __________________ 67 C10 283 T5 swapped longbed fleetside = wife's daily driver 67 C20 292 (originally a 250)4speed longbed fleetside w/original wooden bed=my project truck 67 C10 283+.060 (so a 292 as well)T5 swapped longbed fleetside=my DD 72 C1500 Sierra Grande 350 TH350 longbed fleetside=wife's fair weather truck Can you tell we are fans of longbed fleetsides & 67s Chris

04-28-2023, 12:13 PM	#6
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,190	Re: R44 or R45S plugs?? The extended tip plug came out in the late 50's early 60's for o-head valve engines. All the manufactures soon went with them. They are a big improvement from the recessed tip plugs. The R45S plug is only one step hotter then the R44. That is the best way to go. They should not be used in flathead engines. George

04-28-2023, 12:30 PM	#7
697498chevy Registered User Join Date: Jan 2009 Location: South Carolina Posts: 261	Re: R44 or R45S plugs?? Just checked and I put Autolite 85 plugs in my '69 307 last time . Was that a bad choice ? Seems to run ok . Thanks !

04-28-2023, 02:51 PM	#9
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: R44 or R45S plugs?? The R45S's should be fine in the 69 307 heads. The older motors tend to lose compression and use a little more oil so going one number hotter is probably a good move. I run the same plug in my 427 BBC w/69 closed chamber heads...I found some ACDelco R45S plugs on ebay for a $1 a piece. They were NOS plugs made in the US, they're not anymore. Hard to find US made spark plugs these days and when you do find them they're hot cheap! I'm running Pulstar plugs in my bike... http://toms427impala.info/CT/ACPlugI...Extended%20Tip __________________ Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" "Be American, Buy American"

04-28-2023, 04:25 PM	#11
697498chevy Registered User Join Date: Jan 2009 Location: South Carolina Posts: 261	Re: R44 or R45S plugs?? Thanks , Kaycee !!

04-28-2023, 09:45 PM	#13
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,102	Re: R44 or R45S plugs?? Pretty sure that the product manufactured on different continents is going to be different. Might have not been the case in years past, but now, who knows? __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA

04-28-2023, 10:32 PM	#14
PbFut Registered User Join Date: Feb 2022 Location: Ca Posts: 407	Re: R44 or R45S plugs?? I doubt the difference in manufacturing plant will make such a difference as to be worried. You are going to have a bigger variance in cylinder compression and oil consumption and old plug wire in each hole than you are spark plug difference. The plugs are not likely going to affect a 100 mile plug read. I would use what you got. Look them over at 100 miles and go from there.



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