Gear ratios / RPM at 60 MPH ?

Matthew · Post by **Matthew** » 1st March 2006 - 10:07pm

I need to know what engine RPM I have at 60 MPH.
This is a stock '73 manual FI Fastback on stock tyres.

I can't find gear ratio info anywhere except old reprints of test drive articles in Trevor Alder's "Road Tests and Articles" book - and these are for early models.

Anyone know have any answers?!

Anyone with a tacho care to take a measurement ?!

Thanks.

72_square · Post by **72_square** » 19th March 2006 - 7:33pm

Matt

Not exact by any means, but I was looking at my tach the other day and I was doing about 3000rpm at 60, about 3500 at 65 and about 72 at 4000k.

I'll have a proper look tomorrow as I'm going on a short motorway run. Can't swear my tach is accurate though.

Craig

Matthew · Post by **Matthew** » 2nd April 2006 - 8:40pm

.... about 3000rpm at 60, about 3500 at 65 and about 72 at 4000k.

Thanks. This fits with a comment by Dave Hall that its roughly 20 MPH/1000 RPM.

Can't swear my tach is accurate though.

I doubt many are.

The funny thing is, this is for a dyno run to tell me HP. They quote it to 1 decimal place, and have a HUGE, accurate speedo on the rollers, yet most tachs are probably +- 5% or more error.