Why would you do this? Grey cranks are drop forged and are therefore a very stiff and ridged crank, they have a large lump on the crank to help balance. Grey motors suffer from harmonics at 6200RPM the claim by many of the old school racers is stay above or below it, Those with big HP can push past quickly and are less likely to break a crank.
The Vaxhull crank is a softer crank with these as explained in this conversation with Phillip Barrow:
"Horrible things they are! Stroke too short crank too soft. Every time you rev them they change the piston fazing. Also very high maintenance." says Phil
"Are you pulling my leg, everybody says how good they are!" I asked
"Oh very true. Also very hard to find. I've always done my own. I do it differently than the big dollar conversions I've seen. A lot of work just to gain a little reliability with the catch of high maintenance. They are softer & have larger journals than a grey. They also a better counter weight positioning . Being softer when it flexes it doesn't normally crack unlike a grey crank. But you can only flex so many times until fatigue takes over & it will brake in No6 big end radius just like a grey that makes any sort of power."
What are we chasing and how do you spot one:
"1958 to 1961 Pa Vauxhall Cresta 2.2 liter not the 2.6 . The easy way to check the 2.2 has the dizy in the same spot as a grey & the 2.6 has it like a red ( Holden ) engine"
So whats the biggest rev you have seen on your Phil? And whats the top speed you have seen.
"Ok the highest it has revved is 8300 with the twin 45mm webers. Now do your Maths 15" 60series tyres 3.9:1 diff 1:1 top gear & 8300rpm on conrod just before the chase!"
Check the video of Phils FJ screaming. Who says a grey can't rev!
Knew they were similar; in 1969 I fitted a grey motor to a 1955 Velox..Bolted straight up to the Vauxhall gearbox, same performance.
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