M20 Vs M21 Gearbox

[Jockster]

Norm
With the 3.08 in my FC I am running a fairly warm 192 with twin carbs and headers, originally I had 8 x 13 wheels with 50 series tyres and the car was quick of the mark but not startling and the ratios were a nice split. As my wheels were a little on the wide side I had mudguard clearance problems on the front, so I have changed to 14 x 7 wheels with 65 series tyres. This has made virtually no difference to pick up off the mark and acceleration, but I find that top gear is a little high around town (now we have 50 Km/Hr speed limits). On the open road it cruises fine and actually gained about 4 miles per gallon in economy.
Cheers
Jock

[normd]

Jockster
     Looks like I'll try the 3.08 for a start , fuel consumption is not a worry , it only does about 10 - 12 to the gallon now . Good to know that 14" rims don't make a lot of difference as I've got 8 = 10" x 13's and 2 71/2" x 13's all with special offset.   Years ago to get a lower profile we were using 9" x 13 tyres , gives it  about 2" rim to ground clearence and very little flex in the walls , don't know how that would go for regulations these days  :P
      Thanks for the info mate , Cheers
     Norm

[bjauto]

hi i'm running a 308 with a m20 box with a 2.78 diff and 225/60/14 wheels. havn't had on road as still rebuilding car. do you think iv e gone wrong on my gearing Or will this good running combo as im honesty not to sure. New to this.

[solidsnake308]

i have purchased a m20 box for my 308. but a friend says the box is for a 6cly as the input shaft is 22mm back from the face of my 308 bow housing. sume one please help shed sum light on this, have i been ripped off?

[spanner]

The 6 cyl box output shaft is approx 6 3/4in long from the face of the gearbox housing. The 8 cyl is approx 8in.
Hope this helps
Graham