Top gear mph/1000rpm on a 403 etc.
 

What mph/1000 would I expect on a non o/d 403 (1953). I'm investigating one (LOY555. Anyone know it? It has not much history, the seller has bought a 400 apparently). I'm looking for a car to use & I take my present cars overseas quite often & a good cruising speed is essential. Also what is the 100A engine like on modern fuels...does it suffer from overheating/ vaporisation?
DGH

Top gear mph/1000rpm on a 403 etc.
 

Hi David. I have had my 403 since 1999 and I had an overdrive fitted in 2002. Can't help with a direct answer to your question until I next take the car out but, if it is any help, in overdrive the rev. counter reads 2400 approx. at 70 m.p.h. Fitting the Laycock 'J' Type O/D was the best thing thing I have ever done - it transformed the car. I also take my car abroad a lot. Went to Prague (from London) last year and needed to use fast roads there and back. Would have been miserable without the O/D. Have covered 100000 miles as of this summer and wouldn't have been such a joy without the O/D.
If you get the car, and are within striking distance of London, you are very welcome to come out in my 403. Good luck.
Dave Dale.

Depends what crown wheel and pinion is in the differential. The standard ratio will give c20mph/1000 revs on a Michelin X tyre. The overdrive bumps this up to c25mph/1000. The o/d does make a huge difference; especially if you are thinking of some serious journeys. Less revs = better mpg + less wear all round.

Thanks for that information.
At the moment I have a ZA Magnette & changed the final drive from 4.55:1 (around 15mph:1000!) to 3.9:1 from an MGA mk2 -this meant I was able to cruise at 70-75 (around 4000rpm) & get 32mpg on the Autobahn last year! An overdrive is difficult to fit to the ZA without transmission tunnel surgery.
O/D has to be the way to go, my old TR3A was useless without it! So I have to factor that in to my costs!
Further to fuel, does the head need to be "unleaded" or just use the additive &98 octane?
David