spark plugs for 1958 inline six - The 1947 - Present Chevrolet & GMC Truck Message Board Network

studeclunker · 11-29-2020, 10:38 PM

Okay, we have a one to one-and-a-half ton truck and I would rather use the hotter plugs recommended in the service manual. I searched on line and Autolite 306 is a recommended replacement for the AC-46. Does that sound right? I just want to make sure I have the plugs I need and NAPA has given me the colder plug, Autolite 303 (Comparable to the AC 44). We are coming on cold weather here and I need the old man to start. He's kinda sleepy in his old age.

vince1 · 11-30-2020, 11:03 AM

What engine in that truck? 235/261 or the newer 230/250/292?

I think that in the cross reference charts they give lots of alternatives to the number you put in so maybe the heat ranges aren't as accurate a cross over as they should be.

B4 rings a bell when I bought plugs for a 250. When I bought them for a 350 they were discussing Delco 44 or 45 and I can't remember which they gave me.

Wrenchbender Ret · 11-30-2020, 05:54 PM

The extended tip plugs work much better, like AC 46S or 44s. Its OK to use resister plugs like R46S etc.
George

studeclunker · 12-01-2020, 01:08 PM

As the title says, it's an inline six, and a 235, I think. The Shop Manual doesn't differentiate between the V8 and six. It's just finding the right thing I'm worried about.

Dead Parrot · 12-01-2020, 02:15 PM

According to my old 'Fix Your Chevrolet" book published 1963, the recommended plug for a 1958 235 six banger is an AC44 with a .035 gap. Same plug listed for the 265 and 283 V8.

They switched to the AC46 for the 1962 235.

Autolight 306 does seem to equate to AC46 on this site: https://www.sparkplug-crossreference...rt/AC_DELCO/46

studeclunker · 11-02-2024, 03:48 PM

Here I am looking for the same information and the search function brings up my own post!

Great answers too. Also, this time I'm in Fawn Lodge and have access to my roommate's library of manuals. His Motor's Auto Repair Manual for 1958 gives the gap at .35. In fact, everything that year, V8 or 6 was the same!

Thanks for the answers (a few years later)! They are appreciated. I made this post in case I have to have this info again and my fuzzy memory won't pull it up.

11-29-2020, 10:38 PM	#1
studeclunker Registered User Join Date: Mar 2007 Location: Fawn Lodge, Ca. Posts: 305	spark plugs for 1958 inline six Okay, we have a one to one-and-a-half ton truck and I would rather use the hotter plugs recommended in the service manual. I searched on line and Autolite 306 is a recommended replacement for the AC-46. Does that sound right? I just want to make sure I have the plugs I need and NAPA has given me the colder plug, Autolite 303 (Comparable to the AC 44). We are coming on cold weather here and I need the old man to start. He's kinda sleepy in his old age.

11-30-2020, 11:03 AM	#2
vince1 Registered User Join Date: Jan 2013 Location: Calgary Alberta Posts: 1,170	Re: spark plugs for 1958 inline six What engine in that truck? 235/261 or the newer 230/250/292? I think that in the cross reference charts they give lots of alternatives to the number you put in so maybe the heat ranges aren't as accurate a cross over as they should be. B4 rings a bell when I bought plugs for a 250. When I bought them for a 350 they were discussing Delco 44 or 45 and I can't remember which they gave me. Last edited by vince1; 11-30-2020 at 11:13 AM.

11-30-2020, 05:54 PM	#3
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: spark plugs for 1958 inline six The extended tip plugs work much better, like AC 46S or 44s. Its OK to use resister plugs like R46S etc. George

12-01-2020, 01:08 PM	#4
studeclunker Registered User Join Date: Mar 2007 Location: Fawn Lodge, Ca. Posts: 305	Re: spark plugs for 1958 inline six As the title says, it's an inline six, and a 235, I think. The Shop Manual doesn't differentiate between the V8 and six. It's just finding the right thing I'm worried about.

12-01-2020, 02:15 PM	#5
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,611	Re: spark plugs for 1958 inline six According to my old 'Fix Your Chevrolet" book published 1963, the recommended plug for a 1958 235 six banger is an AC44 with a .035 gap. Same plug listed for the 265 and 283 V8. They switched to the AC46 for the 1962 235. Autolight 306 does seem to equate to AC46 on this site: https://www.sparkplug-crossreference...rt/AC_DELCO/46

11-02-2024, 03:48 PM	#6
studeclunker Registered User Join Date: Mar 2007 Location: Fawn Lodge, Ca. Posts: 305	Re: spark plugs for 1958 inline six Here I am looking for the same information and the search function brings up my own post! Great answers too. Also, this time I'm in Fawn Lodge and have access to my roommate's library of manuals. His Motor's Auto Repair Manual for 1958 gives the gap at .35. In fact, everything that year, V8 or 6 was the same! Thanks for the answers (a few years later)! They are appreciated. I made this post in case I have to have this info again and my fuzzy memory won't pull it up.



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