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December (Xmas) Trivia - Dr Terry
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HK1837 Offline
#1 Posted : Wednesday, 3 December 2025 4:15:20 PM(UTC)
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Thought I'd start this up to try and get more posts happening to get a handle on this Moderation setup.

Two related questions but with different answers. Will throw some more in later.

1. Explain why the 253/4.2 high comp was given an RPO code despite the fact it was not required to have one for HT-HQ prior to LH Torana? L33 exists starting in HT literature but L32 was never applied in any order form or similar literature as it was always the standard engine in all V8 models except for Brougham/Deville and GTS350. For the same reason the 161 never had an RPO code for HK-HG and 173 never had an RPO code for HQ.

2. Following from the above, explain why the LD1 code existed for both 161HC and 173HC engines? They were both standard HK-HQ engines Again the low comp versions were optional engines for all of HK-HQ so you could always option L21 and it exists in PTC lists etc. A big clue exists in the RPO itself in relation to the others around it:

L20 186HC and 202HC
L21 161LC and 173LC
L22 130HC
L23 186LC and 202LC

L30 307 and later HQ 350
L31 308
L32 253HC
L33 253LC
L34 327

LD1???
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Smitty2 Offline
#2 Posted : Wednesday, 3 December 2025 8:14:16 PM(UTC)
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Originally Posted by: HK1837 Go to Quoted Post
Thought I'd start this up to try and get more posts happening to get a handle on this Moderation setup.

Two related questions but with different answers. Will throw some more in later.

1. Explain why the 253/4.2 high comp was given an RPO code despite the fact it was not required to have one for HT-HQ prior to LH Torana? L33 exists starting in HT literature but L32 was never applied in any order form or similar literature as it was always the standard engine in all V8 models except for Brougham/Deville and GTS350. For the same reason the 161 never had an RPO code for HK-HG and 173 never had an RPO code for HQ.

2. Following from the above, explain why the LD1 code existed for both 161HC and 173HC engines? They were both standard HK-HQ engines Again the low comp versions were optional engines for all of HK-HQ so you could always option L21 and it exists in PTC lists etc. A big clue exists in the RPO itself in relation to the others around it:

L20 186HC and 202HC
L21 161LC and 173LC
L22 130HC
L23 186LC and 202LC

L30 307 and later HQ 350
L31 308
L32 253HC
L33 253LC
L34 327

LD1???


great question ! and one I never got a proper answer for when at GMH.
Mechanical engineers at the Bend I spoke to (about all the engine coding)
only ever mention the GM system of 'part grouping' - M for trans, L for
engines, C for HVAC etc
The curly one to throw in is the 'L14' and the best answer I got was
that described a family of engines (... that answer never felt right)

Am curious


Cheers

Club circuit racing...the best fun you can have with your pants on
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HK1837 Offline
#3 Posted : Wednesday, 3 December 2025 8:40:26 PM(UTC)
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There are definite answers to the above two questions.

As for L14, not sure. L66 for 186S is another seemingly random code that doesn’t really fit. I have been digging to see if GMH would have kept L66 for the 202S in HQ, it would have got a code like 186S did as it was to be optional outside of GTS.
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Blu253 Offline
#4 Posted : Thursday, 4 December 2025 7:19:26 AM(UTC)
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Watching with interest.
I have no clue to the answers!
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HK1837 Offline
#5 Posted : Friday, 5 December 2025 7:51:31 AM(UTC)
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Looks like no takers?

Here is the answer to question 1. Pictures tell the story, remember HK only had one model per body/lux level. Whereas as HT had two models per body/lux level - example Belmont sedan 80169 and V8 Belmont sedan 80269. So with 253 planned for release with HK coupes, the 253 was an optional engine whereas in HT-HQ it was always the standard engine in most V8 models. So it needed an RPO code and L32 was given. Otherwise it would never have been given an RPO code until LH Torana. An example of no code is I believe the LC GTR 2600S and 2850S.





You will also notice a few things there in the PTC's that never did happen. Like M22 behind V8. And the planned use of a 6cyl grey iron banjo centre behind a V8 - that never happened either. The V8 banjos were always the stronger nodular 2.78 and 3.08. 3.08 became the standard 253/4.2 manual rear axle ratio for a Holden until HX (but was a Salisbury for HQ and HJ). And 2.78 became the 253 auto ratio until GMH retired the 2.78 Salisbury around the end of HJ.

Edited by user Friday, 5 December 2025 7:57:38 AM(UTC)  | Reason: Not specified

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Blu253 on 5/12/2025(UTC)
Dr Terry Offline
#6 Posted : Friday, 5 December 2025 3:16:15 PM(UTC)
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That makes perfect sense, but IMHO they should just give each engine a name or PO number, whether it was an option or not.

On the same topic I just recently found out that GM-H used the little 130ci Red motor (2150 - not 2250/138) in the HR series. It was P.O. 636 in the HR & then L22 for HK/T/G/Q & LC/LJ I know that the engine no. prefix is 130E for HK/T/G & 130T for early LC. Late LC & LJ was CA, while HQ was QA.

My question is, what is the engine number prefix for the HR.

Dr Terry

Edited by user Friday, 5 December 2025 3:20:08 PM(UTC)  | Reason: Not specified

If at first you don't succeed, just call it Version 1.0
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HK1837 Offline
#7 Posted : Friday, 5 December 2025 3:45:10 PM(UTC)
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Yes Terry, option 636. Only available as RHD, Export only and manual only. Only available on 215, 225, 219 and 229. There is nothing in the HR Eng Tech Specs that spells out its engine number prefix.



Here is where it was added to the Eng Tech Specs:



There was no need to give RPO codes for stuff that was standard, I know its an extreme example but there was no RPO code as far as I know for front drum brakes - you couldn't order it.

Edited by user Friday, 5 December 2025 3:52:10 PM(UTC)  | Reason: Not specified

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HK1837 Offline
#8 Posted : Friday, 5 December 2025 4:25:05 PM(UTC)
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Here is question 2 answer. Again pictures show all.

As per the question, GMH already had L20, L21, L22 and L23.

For LC they added the 138HC but it didn't get an RPO code (sheet 2 below). But they needed codes for the following as they were optional on LC:

161HC and 138LC.

So they used LD1, LD2 and LD3 (not sure why LDx but that is what it was). They used the HK's L22 for the 130HC, but for some odd reason they used LD2 for the 161LC where it already had L21. LD1 continued for the 161HC and into 173HC ongoing, and LD2 continued into LJ to UC for 173LC but L21 was used for 161LC and later 173LC for HT-HZ/VB. That LD2/L21 in an anomaly.

What is also interesting is GMH used LD6 for the 138HC as it replaced the 130 in export HJ and it needed a code being an optional engine. They also used LD4 for the 250ci 6cyl engine in South African Holden and LD9 for the 250HO engine.

Terry, there is another code for you. Not sure if it would have been QB or JB for the 138 (2.25L in HJ) - we need to find one overseas. In theory it would be JB as it was first used in HJ, whereas the LJ version continued with CB as it just carried over.

Smitty, I just remembered LH used L15 and L16 codes for the two different Opel 1900 engines. Not sure why the XT5 3.3 got stuck down with them.


Edited by user Friday, 5 December 2025 4:28:02 PM(UTC)  | Reason: Not specified

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Dr Terry Offline
#9 Posted : Saturday, 6 December 2025 9:01:33 AM(UTC)
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Originally Posted by: HK1837 Go to Quoted Post

What is also interesting is GMH used LD6 for the 138HC as it replaced the 130 in export HJ and it needed a code being an optional engine. They also used LD4 for the 250ci 6cyl engine in South African Holden and LD9 for the 250HO engine.

Terry, there is another code for you. Not sure if it would have been QB or JB for the 138 (2.25L in HJ) - we need to find one overseas. In theory it would be JB as it was first used in HJ, whereas the LJ version continued with CB as it just carried over.


Byron, why wouldn't the 130ci in HJ be QA, because it was seen in HQ & the PO number would've applied in HQ.

On the subject of Chev 6-cyls in HR to AJ in Sth Africa. Were these engines sourced from the USA, or were they built in Sth Africa.

The reason I ask is because in SA they had a very strict local content system based on weight. Things like brake drums, rear axle assemblies gearboxes etc. were built locally to satisfy these rules.

In HR the imported Premier had a Holden 186 with 126 bhp, while the locally built Special had the much heavier 194ci Chev engine with only 120 bhp.

Dr Terry.

If at first you don't succeed, just call it Version 1.0
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HK1837 Offline
#10 Posted : Saturday, 6 December 2025 10:19:19 AM(UTC)
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Terry, the 130ci engine was QA. I was talking about the 138HC that replaced in in HJ. It had never been given a code as it was always standard, so it was later given LD6 for HJ possibly early LH. It'd be HB if used in LH but it won't be QB in HJ as it was not used n HQ, so it must have been JB.

The 250 and 250HO were Port Elizabeth made. They obviously had a grey iron foundry, not sure if these used a forged crankshaft or a nodular one or if imported. They cast big heavy bellhousings to use Australian 3spd M15 boxes behind the Chevy design 6cyl - I have one here.

Edited by user Saturday, 6 December 2025 10:20:04 AM(UTC)  | Reason: Not specified

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