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XU1 valve size

Started by _threeblindmice_ , Jan 31 2016 04:16 PM

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6 replies to this topic

#1 _threeblindmice_

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Posted 31 January 2016 - 04:16 PM

Would anyone have the size of the LJ XU1 inlet valve , and the size of the Bathurst I50 XU1 engine Valve size , I have a new head and would like to know if the valves are going to clear the bore .

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#2 Bazza

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Posted 31 January 2016 - 05:00 PM

Hi

The measurements that I have are: P/N 2822073 (standard) 1.619/1.629 ins (41.12/41.37mm) and P/N 9934043 (after JP386598) 1.715/1.725 ins (43.56/43.81mm)

Cheers

Bazza

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#3 _threeblindmice_

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Posted 31 January 2016 - 09:05 PM

Thanks Bazza , next question , as the head I am looking at has the Bathurst Valves , were the cut outs in the bore for clearance or for airflow ?

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#4 Bazza

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Posted 31 January 2016 - 10:38 PM

Hi

There are others more qualified to comment on this topic than me, but I was always lead to believe the reliefs were to provide additional clearance when the cars were fitted with the higher lift XJ camshaft. But if that is true, the post August '72 JPs would have needed the same reliefs when the XJ grind became available. Perhaps Holden foresaw that race teams would be fitting even higher lift camshafts during 1973 and made allowance for it.

Does anyone have a definitive answer to this?

Cheers

Bazza

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#5 S pack

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Posted 31 January 2016 - 11:38 PM

The fact that Yella Terra have used 1.73" dia. inlet valves in their Holden 6 heads for decades without the need (in most cases) for the bore tops to have valve reliefs probably indicates the valve reliefs in the 150 list XU1 engines were to either, allow better flow around the valve head and/or allow clearance for a camshaft with an insane amount of lift that Harry wanted to run in the HDT cars at Bathurst 1973.

Edited by S pack, 31 January 2016 - 11:39 PM.

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#6 _threeblindmice_

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Posted 01 February 2016 - 07:44 PM

Thanks guys , always appreciate your input !

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#7 73SUNBURSTEXYOUWON

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Name:JASO
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Car:4/73 LJ XU-1. Adelaide build, Sunburst. 1963 EH Premier. Brisbane build, Portsea Blue.
Joined: 14-June 12

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Posted 07 March 2021 - 07:13 PM

Hi all, does anyone actually know or, can anyone with a "9 2 E" homologated engine block, measure the inlet valve cutout radius depth to cylinder bore edge and post the measurement?

TIA