[Michael Mayben]

Edit 7/25/08:

I now realize I made some mistakes when I originally posted this response, I have now corrected the text as appropriate.

One of the BIG "urban myths" which go around regarding IHC-produced vehicles is that "all SV distributors interchange". While it's true that the distributor lower body/drive design does allow any IH-app distributor to be installed in any SV engine, the rest of that statement is bogus.

I'm currently compiling a definitive analysis of all distributors which were used in SV engines (any vehicle platform application), both breaker point-trigger and "electronic" trigger designs. It's not enough today to "ass-ume" that any SV engine has any particular distributor/ignition systems. The PO virus can strike at any time, and the popularity and availability of boneyard crap makes distributor swap a common occurrence. But for working out problems regarding the SV ignition system, we GOTTA know "which" system and "which" distributor is being discussed.

There were/are at least n=thirteen distinct distributor systems used in any SV application dating back to SOP of the 266, and ending with the 304/345/392 series sometime around 1985 (medium duty truck applications).

1) Delco cast iron distributor (four distinct variations).

A) breaker point trigger
B) breaker point trigger w/governor
C) electronic trigger (Magnetic Pulse)
D) electronic trigger (Magnetic Pulse w/governor)
note: the "Magnetic Pulse" units are NOT the same items as the more prevalent Delco Remy "HEI" electronic distributor intro'd around 1973 but NEVER used OEM for IHC.

2) Holley/IH cast aluminum distributor (five distinct variations)

A) breaker point trigger ("straight point" version)
B) breaker point trigger ("curved point" version)
C) electronic trigger ("gold" box)
D) electronic trigger ("black" box)
E) electronic trigger ("silver" box)

3) Holley/IH cast iron distributor (four distinct variations)

A) breaker point trigger ("straight point" version w/governor)
B) breaker point trigger ("straight point" version w/governor and tach drive)
C) breaker point trigger ("curved point" version w/governor)
D) breaker point trigger ("curved point" version w/governor and tach drive)

4) Prestolite cast aluminum distributor (two distinct variations)

A) breaker point trigger
B) electronic trigger (integrated control module)

It is true that several of these units were NOT used OEM in light duty vehicle apps, but as many medium duty vehicles are engine donors for any particular platform, there is no telling what distributor might turn up on any engine! And...there are a few of these items which might be a popular basis for performance upgrade IF they can be positively identified!

Over the next several weeks, we'll try and identify EACH version pictorially and by part number. And to further muddy the waters, most of the distributors in service today are OEM part number...those are units which were supplied ONLY to the engine assembly line! If a distributor was replaced with a complete "service part" item obtained ONLY from an authorized IHC dealer, then a different part number was used to denote "service part". In reality, BOTH of the distributors would have been "spec'd" the same, but carry different part numbers either because of the service parts "emissions" rules (internal corporate policy) or because of packaging differences (assembly line stuff is bulk-packed, service parts are individually boxed, etc.).

Individual part number distributors are then referenced in the appropriate "Truck Service Manual", which is the ONLY place that full distributor specs may be found for comparative purposes. My initial analysis of distributors by part number, show more than thirty-six distinct part numbers/specs!!! And I KNOW that is not all of 'em!

We're kicking this off with an analysis of ONLY SV motor distributors since that's the most prevalent area of interest around here. We'll treat the various I-4 and six cylinder units used in light duty vehicles separately, though the I-4 stuff is virtually identical to the SV with the exception of the 4 cylinder triggering methodology and spec's.