I had heard that too, although not about this HJ coupe but another HQ LS coupe. It might be Chinese whispers along the way that got mixed up. You'd know by the 5.0L engine number in the records against this HJ if it is right for its completion date or if it was changed later. There was a Contessa Gold HQ LS 350 that I saw at the Warwick Nationals that was at once supposedly fitted with a 400 SBC that I have the engine number for that was pulled from Vic Roads records. It was fitted with a HJ 308 and TH400 before it was sold and the records reflect the HJ 5.0L engine. Not sure where the 400 went in the end, it was fitted into the 350Z at some stage and might have left GMH with it in 1975 and that is also where the Vic Roads info comes from. The 400 was meant to be the big engine in HJ (standard in Caprice and optional in other HJ like GTS and Deville) and it was in the Engineering Technical Specs around November 1973. The engine number I have for it indicates it was built in 1971 as an LF6 which was a 255hp 390lbft SAE Gross 2 barrel engine which shows you why the far cheaper local 250hp 320lbft 5.0L engine was used instead.

Just remembered, the 400 when GMH were planning HJ was only a 2BBL if I remember correctly - if you wanted more power from a 400ci engine you ordered a 402. In wasn't unit 1974 model year that a 4 barrel 400 small block was available on passenger vehicles.

Edited by user Monday, 30 May 2022 2:47:12 PM(UTC)  | Reason: Not specified