3 replies to this topic

[rodomo]

When the LC XU-1's raced back in the day, what was the maximum RPM?

 

Was this before double valve springs? Did they use factory springs?

 

I remember my old EH was governed at 4500 due to valve bounce or hydraulic lifter float.

[yel327]

I do recall at least one of the 1970 HDT cars had issues due to the valves and/or springs at Bathurst.
Two other anecdotal examples, Des West said he ran to 6500rpm all day in 1968. The HG 308 GTS Harry and GMH were working on for Bathurst 1971 was to run a 2.55:1 rear axle to keep the engine well below 6000rpm, rods were the issue I believe as well as the valve train.

[rodomo]

Yes, the Brock/Morris and Bond cars had top end problems.

[yel327]

Missed the other question. They were supposed to be totally stock factory engines. We know cheating went on particularly 1969 onwards but it was there earlier too. Whether or not little non homologated engine fiddles went on to increase the durability of engines at higher rpm is a question today probably best asked of Ian Tate or Dave McLean. We know someone (probably Harry Firth) covered his tracks for the 1969 HDT cars some of which used Flint engines rather than the production Tonawanda engines as they added the head casting numbers for the Flint fuelie heads to a parts catalogue amendment. In reality they were the same part number as the production heads, just a different cast mark and cast number.
Dave McLean told me in the past that himself and Ian Tate (and maybe others) were asked by GMH what was needed to make the red 6’s more competitive and durable, and part of the outcome was the bigger rods used later in LJ. I never really discussed LC with him or valve springs or valve train at all with him though, will ask him next time I see or talk to him.

Edited by yel327, 16 March 2020 - 09:16 PM.