27 replies to this topic

[tsn007]

if the L34 engine was purposely built for racing in the Torana

 

i understand it was carried over in the A9X and what changes were made to it, apart from downdraught Webbers 

 

and what was different with the engines in the new VB/VC Commodores that raced

 

cheers

 

[yel327]

The L34 code was actually first used for the 327 in HK.

The GMH L34 engine original development was partially done by Harry Firth and GMH for the Old Man Emu HT/HG Monaro. It was meant to be released as part of the LH XU2 at LH release but they shelved it and replaced with a 5.0L SLR. The car was later released with no RPO code just as an engine option that came with a lot of other.

 

The L34 engine wasn't carried over as such into A9X. GMH put all their homologation paperwork together as per the following to make it look like the L34 model continued into LX SL/R5000 and SS 5000 and then was replaced by the standard SL/R 5000 and SS 5000 from a certain date incorporating all the prior LX SL/R and SS 5000 L34 plus all the A9X goodies (when SLR5000 and SS with L31 became A9X). Smoke and mirrors! 

 

Original homologation H2-4 was for the LH SL/R.

Variant 1/1V was for the SLR5000.

2/2V was for a 3.36 rear axle. None of these would have ever been made as the 3.36 was never available behind a V8. 15/5/74

3/3V was for what we know as the L34. 1/8/74

Evolution 4/1E was for was for new rocker arm studs, modified cylinder head to suit and for additional welding on the exhaust manifolds. Applicable only to SLR5000. 1/10/74 as are all the rest of the Evolutions and Variants up to 12/4V.

5/2E was to delete the timing chain damper. Applicable only to SLR5000.

6/3E was for 12 x stress relief holes on the clutch plate at pressed corners of the spring pockets. SLR5000 only.

7/4E was for 0.75" rear brake cylinders and new brake pedal assembly. SLR5000 L34 only.

8/5E new oil pump, new oil pump drive shaft and new water pump.  New rocker covers both with the old HQ style oil filler caps. SLR5000 L34 only.

9/6E was Mods to rear axle control arm brackets to the underbody. SLR5000 L34 only.

10/7E was an alternative rear axle retainer.

11/8E was the alternative transmission with 2.32 1st gear.

12/4V was the 3.36 rear axle again.

13/9E was the LX SL/R (3.3L). February 1976.

14/5V was LX SLR5000. States a simple carry over from LH with minor changes. Feb 1976.

15/6V LX SS. 2 door carry over of SL/R. Feb 1976.

16/7V SS 5000.

17/8V alloy wheels as alternatives July 1977.

18/10E ADR27A 6cyl engine is SLR and SS/ July 1976

19/11E ADR27A 5.0L engines in SL/R 5000 and SS 5000. February 1976.

20/9V LH SL/R 5000 L34 variant continues in the LX SL/R 5000 L34 vehicle incorporating 13/9E and 14/5V.

21/12E.  From 1 September 1977, SLR 5000 and L34 models discontinued . New model SL/R 5000 with specs as per LX SL/R 5000 L34 with 10 page list of exceptions (this is A9X introduction). Valid from 7/9/76 (not a typo).

22/13E. From 1st September 1977 the specs of the SS 5000 model is varied to include the mechanical specs applicable to the SL/R 5000 as referred to in 21/12E. Plus coachwork mods (pictures of HF-111).

23/10V Borg Warner T10 as alternative gearbox to SL/R 5000 and SS 5000.

24/1E turns lock to lock changed. November 1976.

25/15E a big BS spiel about SL/R and SS evolving from S through the SL. Sept 1977.

26/16E. From 15/9/77 wider flares.

27/17E. UCA running change.

28/11V. Cast iron Borg Warner replaces old T10 with new ratios.

29/12V 3.90:1 rear axle . May 1978.

28/18E. Forged pistons, two different suppliers.

29/19E. Crankshaft weight change.

 

The L34 was a standard 308 with better rods, revised HJ style block, heads modified for larger valves, modified rockers, different pistons and the other external mods that couldn't be changed under Group C (intake, headers, dizzy etc).

 

As you can see GMH homologated new stuff along the way right up until the end of A9X's racing life.

 

From memory (Laurie will correct if wrong), the VB Commodore was raced using the same engines but the A9X lost a few things to hobble it like the rear spoiler and the rear discs. CAMS made HDT use standard size valves, which is what led Brock and HDT to make that VC. It was essentially an L34 version of the XT5 blue 308 with less compression but the bigger HJ-VL camshaft. It didn't have the exhaust headers or the wierdo dizzy but I don't think it had to under the early 80's rules. VH further improved things, but that V5H VC-VK engine was essentially an improved L34 engine.

[a9x868]

The L34 code was actually first used for the 327 in HK.

The GMH L34 engine original development was partially done by Harry Firth and GMH for the Old Man Emu HT/HG Monaro. It was meant to be released as part of the LH XU2 at LH release but they shelved it and replaced with a 5.0L SLR. The car was later released with no RPO code just as an engine option that came with a lot of other.

 

The L34 engine wasn't carried over as such into A9X. GMH put all their homologation paperwork together as per the following to make it look like the L34 model continued into LX SL/R5000 and SS 5000 and then was replaced by the standard SL/R 5000 and SS 5000 from a certain date incorporating all the prior LX SL/R and SS 5000 L34 plus all the A9X goodies (when SLR5000 and SS with L31 became A9X). Smoke and mirrors! 

 

Original homologation H2-4 was for the LH SL/R.

Variant 1/1V was for the SLR5000.

2/2V was for a 3.36 rear axle. None of these would have ever been made as the 3.36 was never available behind a V8. 15/5/74

3/3V was for what we know as the L34. 1/8/74

Evolution 4/1E was for was for new rocker arm studs, modified cylinder head to suit and for additional welding on the exhaust manifolds. Applicable only to SLR5000. 1/10/74 as are all the rest of the Evolutions and Variants up to 12/4V.

5/2E was to delete the timing chain damper. Applicable only to SLR5000.

6/3E was for 12 x stress relief holes on the clutch plate at pressed corners of the spring pockets. SLR5000 only.

7/4E was for 0.75" rear brake cylinders and new brake pedal assembly. SLR5000 L34 only.

8/5E new oil pump, new oil pump drive shaft and new water pump.  New rocker covers both with the old HQ style oil filler caps. SLR5000 L34 only.

9/6E was Mods to rear axle control arm brackets to the underbody. SLR5000 L34 only.

10/7E was an alternative rear axle retainer.

11/8E was the alternative transmission with 2.32 1st gear.

12/4V was the 3.36 rear axle again.

13/9E was the LX SL/R (3.3L). February 1976.

14/5V was LX SLR5000. States a simple carry over from LH with minor changes. Feb 1976.

15/6V LX SS. 2 door carry over of SL/R. Feb 1976.

16/7V SS 5000.

17/8V alloy wheels as alternatives July 1977.

18/10E ADR27A 6cyl engine is SLR and SS/ July 1976

19/11E ADR27A 5.0L engines in SL/R 5000 and SS 5000. February 1976.

20/9V LH SL/R 5000 L34 variant continues in the LX SL/R 5000 L34 vehicle incorporating 13/9E and 14/5V.

21/12E.  From 1 September 1977, SLR 5000 and L34 models discontinued . New model SL/R 5000 with specs as per LX SL/R 5000 L34 with 10 page list of exceptions (this is A9X introduction). Valid from 7/9/76 (not a typo).

22/13E. From 1st September 1977 the specs of the SS 5000 model is varied to include the mechanical specs applicable to the SL/R 5000 as referred to in 21/12E. Plus coachwork mods (pictures of HF-111).

23/10V Borg Warner T10 as alternative gearbox to SL/R 5000 and SS 5000.

24/1E turns lock to lock changed. November 1976.

25/15E a big BS spiel about SL/R and SS evolving from S through the SL. Sept 1977.

26/16E. From 15/9/77 wider flares.

27/17E. UCA running change.

28/11V. Cast iron Borg Warner replaces old T10 with new ratios.

29/12V 3.90:1 rear axle . May 1978.

28/18E. Forged pistons, two different suppliers.

29/19E. Crankshaft weight change.

 

The L34 was a standard 308 with better rods, revised HJ style block, heads modified for larger valves, modified rockers, different pistons and the other external mods that couldn't be changed under Group C (intake, headers, dizzy etc).

 

As you can see GMH homologated new stuff along the way right up until the end of A9X's racing life.

 

From memory (Laurie will correct if wrong), the VB Commodore was raced using the same engines but the A9X lost a few things to hobble it like the rear spoiler and the rear discs. CAMS made HDT use standard size valves, which is what led Brock and HDT to make that VC. It was essentially an L34 version of the XT5 blue 308 with less compression but the bigger HJ-VL camshaft. It didn't have the exhaust headers or the wierdo dizzy but I don't think it had to under the early 80's rules. VH further improved things, but that V5H VC-VK engine was essentially an improved L34 engine.

wow there,s a bit of educated information right there , thanks for sharing

[RallyRed]

Yes, historical info in one place. Nice work.

[IanC]

This is interesting if you haven't already seen it.https://www.whichcar...engine-bathurst

[S pack]

From memory (Laurie will correct if wrong), the VB Commodore was raced using the same engines but the A9X lost a few things to hobble it like the rear spoiler and the rear discs. CAMS made HDT use standard size valves, which is what led Brock and HDT to make that VC. It was essentially an L34 version of the XT5 blue 308 with less compression but the bigger HJ-VL camshaft. It didn't have the exhaust headers or the wierdo dizzy but I don't think it had to under the early 80's rules. VH further improved things, but that V5H VC-VK engine was essentially an improved L34 engine.

The 1980 Group C rules state the Standard size valves must be retained and compression ratio is limited to a maximum of 10.5:1 or that listed on the recognition documents, whichever is the lower value.

Other than that the engine could be built to the same specs as before.

[arrimar]

(1/10/74) 7 variants less than a week before Bathurst on 6/10/74.

Edited by arrimar, 26 May 2023 - 08:34 AM.

[S pack]

(1/10/74) 7 variants less than a week before Bathurst on 6/10/74.

Those weren't variants they were Evolutions of the SL/R 5000 L34 Variant.

Edited by S pack, 26 May 2023 - 08:43 AM.

[yel327]

In that article IanC posted, Ian Tate states the following:

 

“The crankshafts were the problem before GM built some decent cranks, they cracked. Bathurst was (a total) of 620 miles plus practice, so the engines would do 700 miles easy then we’d pull them apart and crack test them. Later on Harrop steel cranks were allowed but a lot guys couldn’t afford them.

 

Makes You wonder if that 1979 Improved Durability crankshaft on 29/19E wasn't a forged crankshaft? The picture is too blurry to check for casting lines or forging marks.

[tsn007]

i thought the L34 engine had a unique block that repco made

 

according to the story ,the commodores ran a normal block but where allowed more freedom

 

 

my real question is, was the vb/vc commodores faster and better in every respect than the l34/a9x

[yel327]

L34 block was an early version of the HJ block. Supposedly better casting material than the production block, but that doesn't produce more power, just makes it more durable.

 

As a road car no. As a race car yes compared the L34. To the A9X, slightly slower for the VC. Tyres, brakes and rubber on the VC especially over the L34.

 

Just look at the 1980 Bathurst qualifying and race time. 2:21.815 for the quickest VC, and the total race time 6:47:52.

 

1974. 2:30.8 for the qualifying time, total race was an hour longer but it was a Ford that did that.

1975. 2:27.4 qualifying. Total race 7:10:3.

1976. 2:25.1 qualifying. Total race 7:7:12.

 

1978 A9X qualifying was 2:20.006, faster than the VC in 1980. 1979 total race time was 6:38:15.

 

Fastest laps I can find, 1979 A9X 2:21.1. 1976 L34 2.28.4. 1980 VC wasn't the fastest, it was Dick Johnson 2:22.2 but that means the VC was slower than the quickest A9X race lap anyway.

 

But that is only Bathurst. And the Commodores got better, by 1982 the VH's were doing 2:17 qualifying times and 2:20 race times, just evolution, rubber and probably better track too. 

[tsn007]

good points

 

true, better rubber, aerodynamics, suspension all had an impact

 

cheers

[yel327]

Remember though that it wasn't an A9X that won Bathurst in 1978 and 1979. It was the evolution of the L34, and this is how GMH framed it in the homologation. The A9X homologations addressed the L34's weaknesses. Ford did the same thing with how they homologated the XA-XC, the main difference being it actually started with 200 XA GT in Series production whereas the LH-LX started with 500 LH SL/R (3.3L) under the 1974 Group C rules.

[eyepeeler]

Remember though that it wasn't an A9X that won Bathurst in 1978 and 1979. It was the evolution of the L34,

 

But it was an A9X in part, a lot of parts were homologated from the A9X production car.

The A9X was used to fix the issues of the Torana racing program, would be a better description I would think.

To say it wasn't an A9X definitively, not sure about that.

 

Although there is 1 part in the doc's that does line up with what you said in how GMH framed it.

21/12E with "specification as for LX SL/R 5000 L34" 

 

But in real terms, to say it's not an A9X that won Bathurst in 78 & 79? Did an XA win in 77?

[Shiney005]

Sheppard was actually campaigning Holden for a 400 Chev small block for homologation of the VB. Rumor has it that the first mule built by HDT had a Chev in it.

 

 Brock VBracer11.jpg   45.57K   8 downloads

[yel327]

But it was an A9X in part, a lot of parts were homologated from the A9X production car.

The A9X was used to fix the issues of the Torana racing program, would be a better description I would think.

To say it wasn't an A9X definitively, not sure about that.

 

Although there is 1 part in the doc's that does line up with what you said in how GMH framed it.

21/12E with "specification as for LX SL/R 5000 L34" 

 

But in real terms, to say it's not an A9X that won Bathurst in 78 & 79? Did an XA win in 77?

 

Put it this way. What raced in 1978 and 1979 were not A9X road cars. Some were upgraded L34, some were upgraded LX bodies. Some were purpose built racing bodies. Whereas most of the L34's raced were real cars. But that isn't what I was getting at. What I meant was the original homologation was 500 LH SL/R's, and that was modified by some Variants and later Evolutions that made the L34 eligible to race. GMH didn't have to build any L34's at all, just a minimum number of parts, however it makes sense to build them as it was the best way to get rid of a lot of those parts. It was the L34 engine, brakes and flares plus other tweaks that made it competitive, not the body shell or the Series. That L34 was further varied and evolved which included the improvements that the A9X gave it, specifically rear discs, bonnet scoop and T10 box plus other tweaks the A9X homologated. However it wasn't an A9X that raced. If road standard A9X's modified to Group C rules raced in 1977-1979 they'd have been running with production rods, pistons and heads plus cast iron exhaust manifolds. Sure the cars might have stopped better, handled better and would have been far more durable than any L34's still racing courtesy of their T10, Salisbury and rear brakes. However the L34's would have out qualified them and probably won all the shorter races. Bathurst - who knows?

 

The 1977 cars were dressed as XB's but a lot of those on the track were XA's. There is no way in hell an XB would have won much of anything if it was raced as an XB. The homologation was from the original XA GT with its 4V 351. Lots of little Variations and Evolutions along the way one of which was for XB body work. Just about any performance parts were done either during XA or into XB production whilst XA were still racing. Like 3/3V for extractors and stronger harmonic balancer. 4/4V for dual point dizzy and modified intake. 5/5V for 31 spline axles, 3.5" tailshaft and 2.75 + 3.25 rear axles. A lot of this stuff was PhaseIII gear intended for the XA GT-HO which was never homologated so they had to add variants basically as XA production was ceasing to make it competitive. There was even a few done well after XA ceased production like 12/12V that added 3.7 rear axle done in November 1973.

[yel327]

Sheppard was actually campaigning Holden for a 400 Chev small block for homologation of the VB. Rumor has it that the first mule built by HDT had a Chev in it.

 

Brock VBracer11.jpg

 

Not sure why they'd want a 400 SBC Laurie? It was only available until 1980 (as in ended by July 1979). Maximum power was only ever 265hp gross. Was only a 4 bolt until 1972 and was rarely a 4BBL. The short rods made it not suitable for high rpm. It was mainly used in trucks and full size lounges. The 350 in 1978-80 wasn't much better though. The highest output version in Corvette (L82) was only good for 220-240hp but that was net hp, still not bad though as the 308 at the time was only 161hp.

[eyepeeler]

However it wasn't an A9X that raced. 

Cams docs support your view, there is no mention of A9X anywhere in that documentation. Won't get an argument from me there.

 

My point was your insistence in not calling it what pretty much everyone else does.

You choose to follow Cams documentation and not use the term A9X when referring to that race car.

 

I don't, it's an A9X in my view.

It's called an A9X on 100% of everything except Cams Docs. I choose to follow that.

Even Holdens People magazine referred to them as A9X Hatchbacks in the Feb 78 edition when Brock returned to HDT. 

[Shiney005]

I call them an A9X as well. Even the spare part cars (GMP&A), but I think Byron has a point here. Especially when you consider Harry's view on what the 1976 L34 was going to look like back in January 1975. The L34 was a whole car. The A9X was just a diff and gearbox. 

 

 Sports Car World (6)small.jpg   123.49K   5 downloads

 

[S pack]

I call them an A9X as well. Even the spare part cars (GMP&A), but I think Byron has a point here. Especially when you consider Harry's view on what the 1976 L34 was going to look like back in January 1975. The L34 was a whole car. The A9X was just a diff and gearbox. 

 

Sports Car World (6)small.jpg

My take on it is, on paper, and solely for the purposes of compliance for Group C Touring Cars, a new model LX SL/R 5000 L34 was born with RPO A9X added. (Evolution 21/12E)

At the same time a new model LX SS 5000 was born, on paper, with the same mechanical specification as the LX SL/R 5000 L34 with A9X. (Evolution 22/13E)

IMO, the Torana's that won Bathurst in 1978 and 1979 were LX SS 5000 L34 A9X.

Edited by S pack, 28 May 2023 - 09:10 AM.

[yel327]

Cams docs support your view, there is no mention of A9X anywhere in that documentation. Won't get an argument from me there.

 

My point was your insistence in not calling it what pretty much everyone else does.

You choose to follow Cams documentation and not use the term A9X when referring to that race car.

 

I don't, it's an A9X in my view.

It's called an A9X on 100% of everything except Cams Docs. I choose to follow that.

Even Holdens People magazine referred to them as A9X Hatchbacks in the Feb 78 edition when Brock returned to HDT. 

 

To be honest I don't care what everyone calls anything, happens all the time when people are wrong and perpetuate it. Like the use of 383 instead of 377 or "the fastest 4 door sedan in the world" or similar incorrect things.

 

The fact is the road cars were A9X, the race cars primarily weren't. Most were L34's changed using bits homologated with the A9X road cars, LH or LX sedan shells, LX hatchback shells or purpose-built race shells with the A9X rear floor pan panel already welded in. Sure they were made to look like A9X but the same applies to the supposed XC Falcons, most or even all were XA or XB. The two Falcons that went 1-2 in 1977 were XB GT's dressed as XC GS (XA GT evolution 34/3E).

 

Nothing I'm saying is meant to be derogatory to A9X, this was just what was basically the start of what happened for many years afterwards where what raced was not what you could buy on the road. When you look at the homolgations for the frontrunners in any of 1970's GroupC era I think the L34 is the only car that was the actual road car raced with GroupC mods. Everything else was either carried over from Series Production or were further evolutions or variations upon what came before them.

[Dr Terry]

My understanding from back in the day was that there was an agreement made between Ford, Holden & CAMS because of the introduction of ADR27A .

 

They agreed that the LX could use the LH (L34) engine & Ford XC could use the XA/XB (351 4V) engine to keep the status quo & make the racing fast, rather than de-tune the series because of the lower horsepower ADR engines.

 

Brock had to homologate the L34-style heads etc. all over again for the Commodore. 

 

Dr Terry

[S pack]

My understanding from back in the day was that there was an agreement made between Ford, Holden & CAMS because of the introduction of ADR27A .

 

They agreed that the LX could use the LH (L34) engine & Ford XC could use the XA/XB (351 4V) engine to keep the status quo & make the racing fast, rather than de-tune the series because of the lower horsepower ADR engines.

 

Brock had to homologate the L34-style heads etc. all over again for the Commodore. 

 

Dr Terry

The LH SL/R 3300 Recognition documents and subsequent Homologation Forms lodged for the SL/R 5000 and SL/R 5000 L34 Variants and Evolutions clearly create the pathway for the L34 package to be carried through and used in the LX SL/R 5000 and SS 5000 models.

 

The XA GT recognition documents do the same thing for the XB and XC.

 

I can't imagine GMH would have wanted to have to produce another 1000 component sets to homologate the L34 package in the new LX model, and there was no need to as the LX model was an Evolution of the LH model. Therefore GMH did not have to re-homologate that which had already been homologated, as long as they stated on the Evolution form that the L34 model continued in the LX SL/R 5000.

 

Commodore was a completely new vehicle series, therefore what had been homologated for LH & LX Torana did not apply to Commodore.

Edited by S pack, 28 May 2023 - 04:03 PM.

[yel327]

Where Ford got caught out is they had homologated the base XA GT (200 vehicles) in 1972 for Series production. The obvious intent to make the XA GT-HO a variation or evolution. The XY GT-HO was an evolution on the XW GT-HO PhaseII. However, with the XA GT-HO being dropped, they had to go through the process of doing variations on the original XA GT homologation from Series production, basically the same way GMH did the LJ XU1 for Group C.

[S pack]

Here is a link to a piece by Mark Oastler about P.B's fight with CAMS over homologation of the big valve L34 style heads for the VC Commodore.

https://www.shannons...s-head-to-head/

 

BTW, 1980 was the year CAMS introduced a new rule in Group C, under engine modifications, which states that 'any anti-pollution equipment may be rendered inoperative or removed'.