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 AR43s vs AR45S vs AR44SJump to page : 1 Now viewing page 1 [50 messages per page] | View previous thread :: View next thread |
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56D500boy |
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Expert 5K+ Posts: 9911     Location: Lower Mainland BC | . I was trying to help a fellow forum member (Jeffrey B) today and that required that I go out to my car in my cold (5 C, 41 F) garage and remove one of the plugs under the recently removed and measured spark plug wire cover. BACKSTORY: When I first got my car in Sept 2016, it wasn't running. Rather that wasting a lot of time, I had it towed to a shop that worked on older cars. While there, they removed the spark plugs and replaced them with AC Delco AR43S plugs. They didn't actually get it going because the carb had to be rebuilt and the water pump calved right there in their shop (they weren't happy with that clean up). When I finally got the engine going in Nov. 2016, after a bit of running, I decided (I can't remember why) that AC45S plugs would be better. So I removed the AR43S plugs and installed the AR45S plugs. Both plugs have a nominal 3/8" reach (not 3/4"). The plug that I just removed today was an AR45S and it was quite black (rich or what?). It also still had the crush washer on it so it would have been pulled back a bit and therefore a bit "cool", perhaps hence the soot - not getting burned off. So rather than re-install that dirty 45S, I found the 43S plugs from 2016 (all in good shape), removed the washer, checked the gap (0.035") and installed it (after removing the spark plug tube and wiping everything off (bit oily inside and out). I think the 43Ss are a hotter plug so I will probably remove the rest of the 45S plugs and swap in the 43Ss. While playing around with the two plug types, I found the attached: a chart that does a cross over from one plug brand to another. See below. My 56 D500 was supposed to use AS-250s which crossed to an AC43 (but not a 43S). A 57 D500 engine like Jeffrey's is supposed to use the AR42 plugs (based on page 505 of the 1957 Dodge Factory Service Manual). According to the attached chart, the AR42 translates to an AC R44S. How much different that is from a R43S or R45S, I have no idea.  See attached photos of 43S vs 45S. I can't tell the difference. What am I missing (no pun intended)?  NOTE: The image of a 270 Dodge hemi combustion chamber with a proper 3/8" reach plug was originally posted by Powerflite (Nathan N.) Thanks for that Nathan. Definitely helped REFERENCE (One 315 Dodge Hemi previous discussion): http://www.forwardlook.net/forums/forums/thread-view.asp?tid=65567&... Edited by 56D500boy 2024-01-11 2:31 AM (SparkplugConversionChart_Annotated.jpg) (Short Reach Dodge SparkPlugInA270Hemi.jpg) (ACDelco43sVs45s_Overview2.jpg) (ACDelco43sVs45s_Detail2.jpg) Attachments ----------------  SparkplugConversionChart_Annotated.jpg (212KB - 27 downloads) Short Reach Dodge SparkPlugInA270Hemi.jpg (164KB - 25 downloads) ACDelco43sVs45s_Overview2.jpg (147KB - 23 downloads) ACDelco43sVs45s_Detail2.jpg (144KB - 24 downloads) | ||
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| mikes2nd |
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Expert 5K+ Posts: 5006 | Yeah that one on the right does not look pretty... and that head is pretty brutal  | ||
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| 56D500boy |
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Expert 5K+ Posts: 9911 Location: Lower Mainland BC | mikes2nd - 2024-01-11 6:51 AM Yeah that one on the right does not look pretty... and that head is pretty brutal I was surprised how fouled it was. But I guess, I just haven't been driving the car enough. (OR it is the wrong heat range). I am slowly starting to understand how the design of the spark plug, particularly the length of the ceramic part beyond the thread seat, impacts the heat situation. That and maybe AC Delco's spark plug nomenclature: R43S as in R = Resistor, 4 = 14 mm, n (3,4 or 5 for my case) = heat range, S = extended tip Edited by 56D500boy 2024-01-11 5:13 PM (ACDelcoSparkPlugNamingChart.jpg) (HotToColdSparkPlugDiagram.jpg) Attachments ---------------- ACDelcoSparkPlugNamingChart.jpg (147KB - 21 downloads) HotToColdSparkPlugDiagram.jpg (142KB - 22 downloads) | ||
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| 56D500boy |
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Expert 5K+ Posts: 9911 Location: Lower Mainland BC | . I was a bit surprised but I see that the 55-58 Parts book does list the sparkplug type, not just the part number for the plug, e.g. 1565 337 = a 4S-250 for a 56 D500 and 1658 851 = AR42 and so on. Finding the modern equivalents might be challenging but I think AC Delco, for one, will have the right plug. | ||
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| 56D500boy |
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Expert 5K+ Posts: 9911 Location: Lower Mainland BC | . I don't know if I have done the right thing or not *BUT* I just replaced my D500's AR45S spark plugs that I had installed in 2016 with the AR43Ss that the first shop I used installed right after I first got my D500. This time I got smart and did NOT use the spark plug crush washers as per the 57 FSM which covered the 57 D500 325 double-rocker and the 56 Chrysler FSM. Started the car and it ran nicely with the clean(er) and re-gapped AR43s. Edited by 56D500boy 2024-03-15 2:44 AM (57DodgeD500rFSMSparkPlugInstallationInfo_small.jpg) (56ChryslerSparkPlugServiceInstructions.jpg) Attachments ---------------- 57DodgeD500rFSMSparkPlugInstallationInfo_small.jpg (218KB - 17 downloads) 56ChryslerSparkPlugServiceInstructions.jpg (148KB - 18 downloads) | ||
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| Viper Guy |
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Expert Posts: 2003 Location: Branson, MO | |||
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| 56D500boy |
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Expert 5K+ Posts: 9911 Location: Lower Mainland BC | Viper Guy - 2024-03-14 7:06 PM Please check the length of the threads. 3/4 inch is longer than 3/8 inch. I think figure A and figure B should be reversed. Don't worry (but thanks for the concern). The AR43S and AR45Ss are both 3/8" reach, the same as the original 4S-250s were. (BUT I think the Chrysler FSM diagram labelling is correct - BUT the note is wrong. I think the Spitfires got the 3/4" reach and the Firepowers the 3/8" reach) Edited by 56D500boy 2024-03-15 2:56 AM | ||
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| Powerflite |
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Expert 5K+ Posts: 9681  Location: So. Cal | No. That's what the label on the Chrysler hemi valve cover says. Always use a 3/4" reach plug on the hemi engine. The Spitfire poly took the shorter plug. (Hemi Spark Plug Instructions.jpg) Attachments ---------------- Hemi Spark Plug Instructions.jpg (220KB - 14 downloads) | ||
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| 56D500boy |
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Expert 5K+ Posts: 9911 Location: Lower Mainland BC | Powerflite - 2024-03-15 7:50 AM No. That's what the label on the Chrysler hemi valve cover says. Always use a 3/4" reach plug on the hemi engine. The Spitfire poly took the shorter plug. "Who's on first?". "Can't tell one player (spark plug) from another without a program. Get yer programs here." I'm confused but I guess I will have to agree that the Chrysler hemi's wanted 3/4" reach plugs. The 57 Dodge tuning specs for the D501 (D500-1) 354 cu in (Chrysler) engine called for AGR32 plugs which are 3/4" reach. Edited by 56D500boy 2024-03-15 1:33 PM (AGR32_For354Hemi_3-4inchReach_small.jpg) Attachments ---------------- AGR32_For354Hemi_3-4inchReach_small.jpg (69KB - 21 downloads) | ||
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