30 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]

I can't believe I missed this thread.  Let me have a crack.

 

Dave is on the money with the homologation docs. My engine was unopened and had the narrrow X's on the rods. You can see in the CAMS page, as well as an interview conducted in 1975 with Mark Andre who worked for REDCO and designed the L34 parts, that the narrow X was around during L34 production.

 

 X rod L34 Homologation.png   613.73K   0 downloads

 

 

 x rod. Story on Mark Andre who designed the parts for REDCO for L34 written end of 1975.png   1.7MB   0 downloads

[Shiney005]

These rods didn't really change until the release of A9L in VL Commodore Group A.   They appeared mainly in V5H and VK Group A, but also turned up in other engines as the L34 motor wasn't homologated for Commodore and 500(?) sets would have been needed to be sold in cars.

The wide X rod that Byron has I think may have appeared in the 1973 X blocks. I thought maybe they may have been used in F5000, but as you can see in the picture below, they are a different kettle of fish.

 Results of Morse Test and broken crank 001b.jpg   286.03K   2 downloads

 

[Shiney005]

Another 1970's pic of the narrow X rod in Fiv's book.

 

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

[yel327]

These rods didn't really change until the release of A9L in VL Commodore Group A. They appeared mainly in V5H and VK Group A, but also turned up in other engines as the L34 motor wasn't homologated for Commodore and 500(?) sets would have been needed to be sold in cars.
The wide X rod that Byron has I think may have appeared in the 1973 X blocks. I thought maybe they may have been used in F5000, but as you can see in the picture below, they are a different kettle of fish.
Results of Morse Test and broken crank 001b.jpg

The 1973 engines are the only other possibility other than L34 back then. Unless these are some sort of special Harry cheat rod made to look like a normal L34 rod?

GroupA required 5000 vehicles then 500 for evolution of type. So 5000 VB prefix 5.0L (304) manual VK engines (basically black version of L34 spec except for bigger cam and lower compression). Then 500 VK Group A with VC engine number prefix.

[Shiney005]

A couple of other interesting bits.

 

This one is an A9L from Larry Perkins 1991 VN. These rods were in VL group A, and then used in all Holden 5.0 V8's from VN onwards apart from the VN Group A rod, which we can call A9L HD. The VN Group A rod was heavier than the A9L so Perkins opted to go with the lighter one for Bathurst. Larry had his rods shot peened, but not linished or polished. A mate of mine once weighed an L34 narrow X rod and an A9L rod, and the L34 rod was heavier. I can't remember by how much.

 

 X rod. A9L used by Larry. Shot peened but not linished or polished..jpg   26K   1 downloads

 

VN Group A rod.

 

 

 x rod. Ex Perkins. Maybe VN Group A.jpg   160.07K   1 downloads

[Shiney005]

So 5000 VB prefix 5.0L (304) manual VK engines (basically black version of L34 spec except for bigger cam and lower compression). Then 500 VK Group A with VC engine number prefix.

Small valve heads and single row timing chain up until VK?