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56D500boy

Posted 2024-02-22 5:57 PM (#633857)
Subject: Early Double Rocker (aka "Hemi") spark plug insulator tube trivia

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I recently purchased a set of used spark plug insulator tubes for my 56 Dodge D500. They were plastic (smelled like a Phenolic, e.g. Bakelite??). I killed them by soaking them in hot(ish) water and Dawn.

But that is another (sad) story, discussed elsewhere.

This post is about what I have now learned while in search for replacements for my now ruined insulator tubes.

We know that there were three different flavours of "Double Rocker" V8s (early Gen 1 hemis) starting with the 1951 Chrysler Fire Power, the 1952 Desoto Fire Dome and the 1953 Dodge Red Rams.

They all must have used spark plug insulation tubes to keep sparks contained and help the mechanics install the spark plug wires onto the top of the spark plugs deep in their metal tubes. That said,
the first PN that I have found is a PN 1369 839 which was also an Auto-Lite SP-994, where the "13" in 1369 839 implies to me as a 1953 part. I don't know what any 1951 or 1953 PNs would be.

The 1369 839/Auto-Lite SP-994 was ceramic.

Not sure when or why but apparently the 1369 839 was superceded to 1473 596 in a plastic (probably Phenolic) probably in 1954.

I do NOT know how long a 1369 839 ceramic insulating tube was/is but the 1473 596 is about 5 1/8" long. This was also an Auto-Lite SP-994-2.

Presumably in 1954, the Dodge hemi got a slightly shorter plastic insulating tube as a 1479 232 which apparently was also an Auto-Lite SP-994-1. Have some of these and they are about 4 3/4" long.

I think ceramic would be the best but I also realize that they would be more expensive to make. Phenolic/Bakelite is a good electrical insulator and it has good heat resistance.

Mopar Mall provides Gen 1 hemi wire sets with a different plastic insulating tube (plastic, about 4 5/8" long). They list the wire set as being for 1953-57 Dodge 241 - 270 - 315 - 325 Hemi;
1952-57 DeSoto Adventurer - Firedome - FireFlite and 951-58 Chrysler New Yorker - 300 and all 1951-58 Imperials.
I bought one these sets for my D500 Double-rocker back in 2016 and I think that it has worked okay.

And that is all I know (for now):

Edited by 56D500boy 2024-02-22 6:35 PM