What spark plugs for a 56' 322?

[Guest imported_56BuickSuper]

I know the book calls for the AC 44. I have changed over to the Pentronic set up, is there a better choice. Also, the gap spec is 30 - 35, should this be increased for the Pentronic?

thanks

Dan

[raleets]

Dan,

I'm not much of a mechanic, but I recently changed plugs on my '56 322 also. Couldn't find 44's either, so I used 43's. They worked GREAT!

I don't have Petronix on my '56, but I do on my '62 with a 215 V-8. I gapped those at 45 and it runs like a fine watch.

Hope this helps,

Bob Leets <img src="http://www.aaca.org/ubbthreads/images/graemlins/grin.gif" alt="" />

[FireballV8]

Dan

I think I have a set of the 43's if your interested, email me steveclassic@earthlink.net

thx

[Guest imported_56BuickSuper]

I got a set of Champion 871 RJ8C. Will these be good?

Dan

[NTX5467]

The AC plugs with a "44" number were a pretty much middle-range heat range plug. Lots of Chevy small blocks used a 44 plug too back then and in later years.

As for the gap, you could do a lot worse than staying with the orig plug gap spec. With any ignition, widening the gap will make the coil build up a little more voltage before it fires plus expose a little more of the spark to the mixture inside the combustion chamber in the process. You might experiment with the .045" gap and see if it works for your setup. If it doesn't, just set it back to a little closer gap and all that's been contributed to research is a little of your time.

Going one notch colder on the plug (as from a 44 to a 43) should cause no problems if the 44s were working fine as they were. Going one notch colder can also allow a few more degrees of spark timing without "overheating" the plug, too, but more like 2-4 degrees. Always better to go colder than hotter in an engine that's fine internally.

I don't know how much room is in that combustion chamber, but a "44S" plug is the same heat range as the normal 44 plug, but has an "extended tip" which puts the center electrodes a little farther into the combustion chamber. Some engines have no problems going from a regular tip to an extended tip plug, so I'll defer to those more knowledgeable on that particular motor on whether or not anyone has tried this on those particular engines and have lived to tell about it.

Back to the "labor operation" situation, you can "J-Gap" your regular plugs with a little time and simple tools. The "J-Gap" style gap was used by Champion on some of their racing plugs in the 1960s. What it amounts to is snipping and filing the end square on the ground electrode of the plug and then regapping it to specs. End result, the gound electrode is cut back to where it only covers 1/2 of the center electrode when it's all said and done. This exposes more of the spark kernel to the mixture and promotes a better burn. AC Rapidfires are this was as are NGK V-Power plugs. J-gap modifications would not work on platinum or "fine wire electrode" plugs, but will work on the regular electrode plugs.

I believe there is a competitive cross reference and probably a parts lookup section on the ACDelco website.

One trend of modern spark plug design is to decrease the voltage requirement of the plug so that a good solid reliable spark is produced without having to have a super power ignition system. Similarly, with a given coil, it could also allow the gap to be widened further. There are many spark plug manufacturer websites that have information on their products so there's lots of stuff to look at out there. Probably some cross refs among the various brands for particular applications too.

Just some thoughts . . .

NTX5467

[Guest imported_56BuickSuper]

Thanks for the excellent response. I did not having any luck with the cross reference lists from champion to AC so I put in the champion number on the AC site and it came back with AC 45. Thinking this may be a little hot, I went to NAPA and picked up a set of 43R's. The R is for resistor plugs so that should not be an issue. When I did the ignition I also did the coil replacement, so that said I am going to try the wider gap. Since I have the time I am going to also do the "J-Gap" modification you mentioned.

Dan

[old-tank]

I put AC R43 plugs in my 55 322 and they were fouled in 20 miles. That also was using Petronix. So I cleaned an old set of AC44's, set the gap at 0.040 and after 22,000 miles they still look like new. Using the plain 43 44 or 45 plugs will probably be OK. My wires are solid wire.

Just my experiences.

Willie