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Torana L34 - motor configuration/s ?


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#1 HeskethBoy

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Posted 14 May 2012 - 01:34

Trying to understand if there were different 5 litre englines in the L34 (not the standard SLR5000-sedan which had the L31 motor).
Did these cars have Repco based blocks, or not?

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#2 Welby

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Posted 14 May 2012 - 03:05

L34 was the RPO designation for the uprated 308 cu i ( 5 L ) Holden engine.
It was an improvement in durability and strength, but not a new engine.
It was based on the standard engine but had extra webbing cast into it.
It had components specific to racing use, pistons etc
The heads were specific to the engine with bigger valves, roller rockers etc.
The engine was designed with influence from the engineers at Repco and i believe ( but happy to be wrong) that they were cast offsite at the Commonwealth Aircraft Company.

Was an excellent piece of kit.





#3 Lee Nicolle

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Posted 14 May 2012 - 08:27

The L34 engine was a production engine with a few upgrade parts. Heads were given bigger valves and a tidy up by Perfectune, blocks were supposed to be improved BUT not the ones I have seen. Slightly better rods and crank, twin coil ignition, open plenum under the carby, short stub extractors, roller tip tin rockers. Blocks etc were all done by GMH.

The race engines were supposed to be better, you could buy some of the go fast stuff from your GMH dealer and they sounded impressive for the day.
proper race engines found a LOT of faults. Harry was and still is critical of what they did. Read the Muscle Car articles.

Some road cars missed out on the 'good' bits. I rebuilt a stock unmolested L34 motor about 1980 and it was a stock 308 with only the external bits.It had lost a cam and was fumy and oiled up 1 plug, normal broken rings the 308s often had.Before and after it was a gutless thing, my mates LH 5000 was a LOT faster as a stocky. But did not stop like the L34.Though the 5000 was hammerd from new and the L34 was owned by a school teacher who was quite conservative. He traded it on a Celica!

I have seen one other standard L34 motor and it had the good heads and rods and externals but otherwise was a standard 308 gunker.
Pistons were free for racing, as was a lot of other things.That is why Holden just used the standard stuff to homolgate the parts,, without another Supercar scare.

#4 Piquet959

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Posted 14 May 2012 - 10:41

I had an L34 as a road car in the period. Sadly it was stolen never to be recovered. Whenever I see an L34 I always check them out as I still think mine might be around and I had modified it in such a way that I could still recognise it if I was to ever see it.

There were quite a few subtle differences between a normal 308 and the L34.
The differences can be seen when reading the L34 parts catalogue.

The main bearing bolts were different because the engine had a wind age tray fitted. So the bolts had like extra 1/4 or 5/15 thread sticking out the bottom so that the wind age tray could be mounted on the main caps.
The water pump was different, the oil pump was also also different. The sump had some extra baffling fitted
I think that the oil pump drive shaft was also different.
The fuel pump was also a higher output as was the size of the fuel line increased in diameter.
The timing case was also different.
They were also fitted with a double row timing chain. I'm not sure but think that the standard 308 had a single row fitted. I know the 253 definitely had a single row timing chain.

The conrods were much beefier and had larger big end bolts fitted with an "X" forged into them.
The quadrajet carby was also different and had a manual choke fitted as opposed to the normal auto choke.

The roller rockers that were fitted were the normal tin/ metal rockers but had a roller cage fitted inside them. This classified them as a roller rocker so that " proper" roller tip rockers cold be fitted to the race engines. These were mounted to the head with a bolt rather than the presses I stud on the normal 308 heads.

The dissy was a twin coil twin point thing. Mine had a plate screwed to where the vacuum advance was normally fitted that had stamped on it "modified by repco". They were a difficult thing to keep in timing and not many tuners could set them up correctly. I eventually sold mine and went to a normal dissy with an optoelectronic ignition system. The change to the twin coil twin point setup meant that the tachometer eas different as it was set up pick up the signal off one side of the dissy so essentially was a 4 cylinder tacho.

The inlet manifold was modified by way of the opening under the carby was all machined out.
The normal cast exhaust manifolds were removed and a set of HM Headers/ extractors fitted. Some additional extractor taile were available from HM which made a significant difference to the exhaust flow.

The block had extra webbing round the rear main bearing area. The pistons were a slipper type and quite light weight when compared to a standard 308. (I still have a set in the shed). I believe that the oil galleries were also modified although I think that the modification was really just cleaning them up and getting rid of any draggy bits.

As was stated previously the heads were modified by Perfectune. The valves were a good deal bigger than standard.

If I can find my parts catalogue I will see what else is different
Cheers
Peter Sneddon

Edited by Piquet959, 14 May 2012 - 10:43.


#5 Ray Bell

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Posted 14 May 2012 - 12:30

Originally posted by Lee Nicolle
.....Harry was and still is critical of what they did. Read the Muscle Car articles.....


I would be careful of anything Harry says of this nature...

He is always critical of everyone else and very quick to claim all the kudos for anything that worked right.

#6 Lee Nicolle

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Posted 14 May 2012 - 23:57

I would be careful of anything Harry says of this nature...

He is always critical of everyone else and very quick to claim all the kudos for anything that worked right.

Since the things regularly grenaded through lack of a decent sump and oiling he was probably right. Yes he is a grumpy old bugger but he did work aroung GMHs lack of design

As for decent pistons they were in the performance book. They had standard cast pistons from the factory. And all plastic engines from that era [up to about 79] had a double row chain. Not a true roller just a roller style. Later engines [VK VL] has single row chains on double row gears which again cost a lot of engines and a sure Bathurst win. Those rules were so dumb. As was the manufacturer for skimping on basic engineeering knowing the chains failed regularly on standard road cars.
The standard GMH chain used to be about $15. They were all stretched to blazes very prematurely, but the cam and lifters were worn out so you did them both. Regularly.
Some replacement ones these days seem to be better material, or maybe just better oils as they do not seem to fail as often in the old red/blue/ black engines.

Edited by Lee Nicolle, 15 May 2012 - 00:12.


#7 Piquet959

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Posted 15 May 2012 - 01:30

Harry grumpy.......never happened!

#8 Ray Bell

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Posted 15 May 2012 - 07:24

Originally posted by Piquet959
Harry grumpy.......never happened!


Of course, my post was nothing about how grumpy he was...

It was about the accuracy of what he said!