39 replies to this topic

[Peterpilot]

Conrods, I heard that L-34 blocks had an "X" cast on the block, might have something to do with it. However, I don't know if this is true, nor do I know if L-34 conrods were different to standard.

[lakeside]

L34 rod have the cross. The blk motors and on, have the same rod with no cross which are called A9L rods. L34's are a stronger rod with bigger bolts, than the standard ones.

[LXdamo]

like these


one on the left is a L34 or "X" rod,centre is an A9L and the stock one is on the end
A9L's also have larger rod bolts
My "X" rods came out of a standard VL 308

Edited by LXdamo, 02 December 2006 - 09:35 PM.

[micklx]

I believe L35 rods had the large X, A9L rods (VK Group A etc) had the small X, VN onward had the spike and VN Group A had the spike as well as more meat around the rod bolts (but weigh 45 grams more than the std VN rod which some people find undesireable).
All these rods had 3/8 bolts where the standard Holden rod bolt is slightly smaller.
Production A9X's had the standard rods.

[sharpie]

From what Ive seen from videos and picks of rebuilds (and Shiney005's reseal) the small elongated x on the rod is the L34 rod, yet LXdamo has one come out of a standard VL? I've also seen people with the large square x also claim to be L34.  L34 rods are the only factory rods forged from what I understand, and everything else is cast, including the A9L spike, the chunky group C A9L rod, so I assume the large square x rod is from the Vk VL Commies( assuming they did actually come out with a x rod ?),which doesnt explain LXdamos rod. I'm also not sure if the A9L spike is pressed powdered metal as it has a smoother finish.  Is there a cast rod with a small X identical to the L34 in the commodores that is cast? or is that the large square X? Does anyone know for sure? How can you tell if you have a forged L34 rod? The parting face on the sides of all the rods seem to be ground so its hard to tell between cast and forged, for me anyway? is there a weight difference? How many variations of rod are there for production holden V8's? Has micklx got it right or just mixed the x's around? And LXdamo's rod? Any help would be greatly appreciated.

[yel327]

Wide X is L34. I used to pull rods out of VK engines in the 80’s which were the narrow X. I still have some and one L34 rod, they are identical apart from the X width. Both are cast, they appear to be the same cast pattern other than the X width.

Will attach photos later.

[sharpie]

ok thats what I originally thought but there are contradictions. First the L34 rod was apparently a forged rod produced by Repco.

https://classicthrot...rce=chatgpt.com

 

This is in a genuine L34, Shiney005's reseal pic 

https://www.gmh-tora...attach_id=40446

it is the small elongated x 

 

this is also out of a genuine L34

https://www.my105.co...0c-cfc6e8c8eef5

 

another pic of the small elongated x

https://www.justpart...con-rods-x-rods)/JPM4024184

 

but we have LXdamo and you to confirm the small x is in the VK and VL

 

this is what I thought the L34 x was, the wide square X

https://www.facebook...58544292&type=3

 

whats going on??? is this an aftermarket L34 rod?

Edited by sharpie, 11 October 2025 - 12:40 PM.

[sharpie]

ok... I've had a look around and there are people saying L34 are forged but nothing reliable and there doesnt seem to be anything official stating they are forged so ...  they are probably not forged as yel327 stated.

 

So, if the same x is in l34 toranas and vk commies then perhaps they are the same rod...A stronger rod needed for the vk untill the spike came out.. makes sense. But its only an assumption.

 

Still doesnt account for the large x rod, unless it was aftermarket, or there are 2 x L34 rods. maybe one was forged? maybe the guys that raced a9x homologation race cars used them with the rule changes??  too many maybes. Help...

[yel327]

I found two sets of V5H rods in my shed and a single L34. The L34 looks cast to me.

 

A couple of V5H rods. The X is not symmetrical, you can see sometimes the smaller bit is upwards and sometimes downwards:

 

 V5H a.jpg   169.96K   2 downloads  V5H b.jpg   168.75K   2 downloads

 

L34 rod:

 

 L34.jpg   311.44K   2 downloads

 

Side by side:

 

 V5H v L34.jpg   470.18K   4 downloads

 

 

[sharpie]

Thanks yel327. Are you sure the large x is L34? Because I've seen 3 examples of the small elongated V5H engine "X"rod that are exactly the same in genuine L34 engines. The large X isnt the same as in documented L34s Ive seen, unless there was an early and late version of the rods and they are both L34.

 

It appears that the same small x rod was used in both L34 and V5H? 

[yel327]

I’m not sure, but I was given that one in the 80’s and told it was ex-L34.

[S pack]

Looking at the L34 conrod photo in the LH Torana SL/R homologation documents the smaller X rod on the right looks like the L34 rod, especially the design of the cap.

 

 

 

Edited by S pack, 11 October 2025 - 07:55 PM.

[sharpie]

There does seem to be a few of the large x rods around, and many people know of them and assume they are L34. Would be interesting to know what they are.

 

[yel327]

There does seem to be a few of the large x rods around, and many people know of them and assume they are L34. Would be interesting to know what they are.

 

They have to be L34 or F5000, cannot be anything else. Same length, same construction, same bearing bore size. Just have a heavier duty cap. The ones I have with the narrow X 100% came out of VK engines - I pulled them apart myself.

[Shiney005]

They aren't F5000. Rods were free in that category and the ones they used looked more like an early Carillo.

 

 Results of Morse Test and broken crank 001b.jpg   286.03K   4 downloads

[Shiney005]

My thinking is that the wide X rods may have been in the 1973 motors with the X blocks.  The narrow X rods were in production L34's as can be seen in the article on Mark Andre who worke for REDCO and designed alot of the L34 engine parts, and as Dave alluded to earlier, you can also see the narrow X in the homologation documents. The main difference between the wide and the narrow is that the narrow has a much heavier duty cap.

 

 x rod. Story on Mark Andre who designed the parts for REDCO for L34 written end of 1975.png   1.7MB   6 downloads

 

 

 X rod L34 Homologation.png   613.73K   1 downloads

[Shiney005]

The reason that they were found in later Commodores may have something to do with the homologation requirements? Only 263 cars were built, so I guess there would have to be another 237 sets of rods made to get them to 500?

 

Just for curiosity's sake...............

 

Early standard rod with the cast letters on the beam.

 

 Standard early with cast letters on shank 2 (1).png   1.4MB   1 downloads

 

A9L rod. These first appeared in the VL Group A. They became the standard rod in all V8's from VN onwards, except for VN Group A which had a heavier one again.  The one pictured is from Larry Perkins 1993 VP Bathurst car. They were shotpeened, but not linished or polished. Larry stated that after 1000 kays of racing they were still in perfect condition.  He preferred the A9L rod over the VN Group A because they were lighter.

 

 A9L used by Larry Perkins at Bathurst. VN Group A rod deemed too heavy 1.jpg   216.5K   0 downloads

 

Another early photo of the narrow X from Fiv's book.

 

 x rod. Fivs book 1.png   1.27MB   1 downloads

Edited by Shiney005, 22 October 2025 - 02:02 PM.

[Shiney005]

Another interesting tidbit is that some 350 Chev rods had the X as well. These were mainly fitted into 1970's truck engines and the X was cast into the cap.

 

 X rod Chev. Small x stamped on cap. Usually found on Blazers and C20's 3.png   765.74K   0 downloads

[sharpie]

Are any of these factory/Repco L34 X rods forged? There are there so many examples of people stating they are forged? If they are all just cast are the L34 small X a beefier rod or basically a standard rod with the 3/8 bolts?

[yel327]

The reason that they were found in later Commodores may have something to do with the homologation requirements? Only 263 cars were built, so I guess there would have to be another 237 sets of rods made to get them to 500?

Just for curiosity's sake...............

Early standard rod with the cast letters on the beam.

Standard early with cast letters on shank 2 (1).png

A9L rod. These first appeared in the VL Group A. They became the standard rod in all V8's from VN onwards, except for VN Group A which had a heavier one again. The one pictured is from Larry Perkins 1993 VP Bathurst car. They were shotpeened, but not linished or polished. Larry stated that after 1000 kays of racing they were still in perfect condition. He preferred the A9L rod over the VN Group A because they were lighter.

A9L used by Larry Perkins at Bathurst. VN Group A rod deemed too heavy 1.jpg



Another early photo of the narrow X from Fiv's book.

x rod. Fivs book 1.png

They became standard in Commodore and Calais in the early-mid 80’s. There must be many thousands of them, for starters there were 5000 V5H 304 engines, plus all the other engines.
I reckon the earlier wide X rods have a heavier duty cap on them.