44 replies to this topic

[grumpy xu1]

Hi guy's just wondering what head a 12-9-72 brisy built xu1 that came with nibless wheels from new should have ? Thinking maybe a 25h2, presently has a c233 fitted in good condition assuming a gmh done replacement. Gary. 

[FLY_AGAIN_XU-1]

A H252 (9H) to be exact. There were 4 runs of the H252 XU-1 head, 9H, 10H, 11H & 12H. This is the number found at the back of the head. The H252 11H & 12H were the spare parts and are one of the easiest to locate and most common of all the XU-1 heads. At Sandown in September 1972, which was also the 2nd round of the Manufacturers Championship, both Peter Brock and Colin Bond blew their engines. Very rare for a HDT car to blow an engine, let alone both. At first it was thought it may of had something to do with the newly homologated XJ camshaft or maybe the newly homologated lightened flywheel. It was later discovered that a bad batch of valves in the newly cast H head was the cause. The valves had not been heat treated. After this discovery Holden recalled all of its September 1972 built LJ XU-1,s with many receiving replacement heads. That was provided you had not all ready blown your engine. This is the reason why a H252 9H remains a very rare head indeed. Peter Brock went on to win round 3 of the Manufacturers Championship " Bathurst " in October 1972 without any mechanical issues what so ever. Peter Brock's first " Bathurst " win of many.......

There were also 4 runs of the C233 XU-1 head. The 3H was used on the 4/73 & 5/73 production XU-1,s. The 7H was used on the early July 1973 cars, with the 9H & 10H being for spares.....

Edited by FLY_AGAIN_XU-1, 31 January 2021 - 11:27 AM.

[crabba67]

The H252 9H head started at JP 219### with one of cast dates being the same day

Edited by crabba67, 31 January 2021 - 12:41 PM.

[grumpy xu1]

Without sounding like a smart eleck, where have you got the engine number start date from Crabba, i have seen apparent original car's before 219, had the h252 heads ?

[crabba67]

So which xu1's are you referring to? if it's a JP212### all are built on 1/9/72 at Brisbane so impossible with a head cast on the 25th of August 72 to have a H252 head.One Example at Adelaide is L213718 recorded on the 15/9/72 it's Broadcast sheet states it was built on the 4/9/72 and was also sold and registered before the 15/9/72.

 

Also there are (3) remaining original JP217### blocks all have E172 heads

[grumpy xu1]

Yes i was talking about say Brisbane built in the 218 range. Say 2nd week of September roughly. I've seen the very end of August cars running the E172 heads still.

[crabba67]

No such thing as a 218 ....... the first JP219 is Built on the 12th of September at Brisbane You must allow a least 13 to 14 days from casting date to the car being built

[FLY_AGAIN_XU-1]

There were also 4 runs for the E172 XU-1 head :

 

E172   : 5H, 6H, 7H & 8H

H252   : 9H, 10H, 11H, & 12H

 

There were only 2 runs for the L32 XU-1 head :

 

L32   : 11H & 12H

 

The L32 11H was mainly used in the November 1972 run of LJ XU-1,s while the L32 12H was used mainly in the first run of 1973 LJ XU-1,s ( 2/73 ) prior to the release of the C233 XU-1 head for the second run of 1973 LJ XU-1,s ( 4/73 & 5/73 ). These 2 runs of 1973 LJ XU-1,s bringing the total to 500, the minimum number required under the C.A.M.S. Group C rules for eligibility.........

[yel327]

Hang on a sec. You are claiming GMH had to build 500 LJ XU1 in 1973 to be eligible for 1973 Group C? I'm not sure if that is what is meant but it sure does read that way? If that is the case, can you show us the extra 500 VH E49 or XY GT-HO built for the same purpose?

If those 500 XU1 required were completed in 4/73 and 5/73 then allowing the LJ to race in GroupC, what was racing in the ATCC races in March, April and May 1973? And also in the South Pacific Touring Car Championship races in February 1973? Any images or footage from those races appears to show LJ XU1's in GroupC trim?

 

Might all be stupid questions but it doesn't make sense to me.

 

Aren't those numbers in front of the H simply pattern numbers? GMH had multiple patterns of the same thing for just about all castings, and they were all numbered, In order to make enough green sand moulds to do a run on one day they'd need multiple patterns to make the required number of green sand moulds.

[grumpy xu1]

No such thing as a 218 ....... the first JP219 is Built on the 12th of September at Brisbane You must allow a least 13 to 14 days from casting date to the car being built

Okay, but the h252 head was used before the jp 219### from Brisbane, you would have actually seen 1, i think. It was the week before.

[crabba67]

So which are you talking about with alj118,alj119 or alj121 xu1’s or jp216 in the first week........... Remember all blocks were made,assembled and racked in Melbourne

Edited by crabba67, 02 February 2021 - 06:59 PM.

[grumpy xu1]

To stop any confusion, 25h2 heads on car's assembled a week before jp 219### then, i know of 1 & you would to, it's a Brisbane built car, built at the end of the previous week. All i was stating was that 25h2, didn't start at jp219###. I may have read wrong, but i thought that was what you had previously stated ?

[crabba67]

You can't have a head cast on the 25th August 1972 in a car built from the 1st September to the 7th September 72.It started on the 12th September 72 which are JP219 .......

[FLY_AGAIN_XU-1]

It's a bit like having an E172 on your 3/72 LJ XU-1.

[FLY_AGAIN_XU-1]

Hang on a sec. You are claiming GMH had to build 500 LJ XU1 in 1973 to be eligible for 1973 Group C? I'm not sure if that is what is meant but it sure does read that way? If that is the case, can you show us the extra 500 VH E49 or XY GT-HO built for the same purpose?

If those 500 XU1 required were completed in 4/73 and 5/73 then allowing the LJ to race in GroupC, what was racing in the ATCC races in March, April and May 1973? And also in the South Pacific Touring Car Championship races in February 1973? Any images or footage from those races appears to show LJ XU1's in GroupC trim?

 

Might all be stupid questions but it doesn't make sense to me.

 

All the cars you have quoted, including the race cars, are either 1971 or 1972 models. To race a 1973 model in 1973 required 500 to be built to be eligible.

 

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[yel327]

You can't have a head cast on the 25th August 1972 in a car built from the 1st September to the 7th September 72.It started on the 12th September 72 which are JP219 .......

I agree with you Anthony that this timeframe is tight and what you say is more than likely the norm, however an engine block or head can easily be on a completed engine ready to go inside two days. GMH was no different to any other GM foundry or engine plant with how it worked. I have numerous examples of Tonawanda and McKinnon engines with a completion date only 2 days after the cast date of the block or head(s). Sometimes up to a week, sometimes many months. So there is no physically impossible barrier to a head cast on 25th August being on a running engine on say 29th August (25th was a Friday), crated up and freighted to Acacia Ridge and arrived on 2-4th September. Then be in a car on the 5th or maybe earlier. If a car (as in a painted and hard trimmed body) was waiting for an engine to arrive before it went into the Assembly Plant it may have been faster.
As I said this is tight but it could and did happen. Remember the body and assembly plants didn’t have massive storage areas, everything arrived at the site on a “just in time” basis according to the schedule. So stuff didn’t hang around waiting to go on a car. A large number of cars a day were being assembled and component parts used in the assembly plant were used as they arrived, normally within a day or two.

[crabba67]

Not in this case not with xu1’s ...... I have researched it a lot the same with HQ’s give Andy a call you know who I mean

[yel327]

All the cars you have quoted, including the race cars, are either 1971 or 1972 models. To race a 1973 model in 1973 required 500 to be built to be eligible.

731-1.jpg

That cannot be correct. Those words do not stipulate 500 cars actually built in 1973, just 500 of that car. The LJ XU1 was a current production car, from memory it was accepted into GroupC 1973 as it was already homologated the prior year and the homologation continued to be amended. It was never “re-homologated” for 1973. Old memory but I’m sure the words go something like it doesn’t matter when it was made, just that the car met the specifications. Or something to that effect. Otherwise no-one would even bother, just use a 1972 shell and apply GroupC freedoms.

[yel327]

Not in this case not with xu1’s ...... I have researched it a lot the same with HQ’s give Andy a call you know who I mean

No I don’t know who you mean. But I understand you’ve seen a lot of them. But not all of them. Which I have learnt over the years, there are always exceptions to the norm.

[FLY_AGAIN_XU-1]

That cannot be correct. Those words do not stipulate 500 cars actually built in 1973, just 500 of that car. 

 

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[yel327]

You just posted the same thing? Where does it state they all have to be built in 1973? It doesn't. To me it reads logically that for GroupC (only valid until December 1973) that for locally produced cars in order to be recognised, that 500 basically identical units must be produced. If the LJ XU1 was only produced in 1973 and not homologated for GroupE then GMH would have to have built 500 basically identical units (unless I guess it was an evolution of type). That is exactly how that those words read. However the LJ XU1 was never homologated under 1973 rules, it was automatically accepted into GroupC as it was homologated under GroupE, just like the VH E49 and the XY GT-GHO and the LC GTR and possibly others. All of those 3 raced in 1973 as GroupC cars with GroupC freedoms. The LJ XU1 was no different. I cannot understand how that can be interpreted any differently?

I'm pretty sure the 1973 ATC regulations also say something along the lines of if a car shows complete compliance with its recognition form, the year of manufacture shall be immaterial.

[FLY_AGAIN_XU-1]

I'm pretty sure the 1973 ATC regulations also say something along the lines of if a car shows complete compliance with its recognition form, the year of manufacture shall be immaterial.

 

Exactly, provided it is eligible. The problem is the bit you have quoted is from the 1972 Group E Series Production Touring Car Rules and not from the 1973 Group C Production Touring Car Rules.

[yel327]

Which the LJ XU1 was eligible as it was already homologated. Similar provisions had to apply though to ex Series production vehicles or there would’ve nothing to race in 1973? The bulk of cars raced in GroupC especially early on were 1971-2 bodies. Even the XA homologation process began in March 1972 with recognition of 200 identical model JG33 units.
If GMH had to build 500 extra LJ XU1 to compete in 1973 where is the recognition documentation for it? Ford didn’t build anywhere near that number of XA JG66 in 1973, only about 360-ish and 120 of those were the RPO83 built in August 1973. So none of that makes any logical sense.

[FLY_AGAIN_XU-1]

and how many XA JG33,s in 1973 ( 4 Doors )  and how many 4 door 1973 XA RPO-83,s ?