my mte had same problem .... my ute could get up 2 160km stock with a12 in it but took a while 2 get there! i think its prolly got 2 do with gear ratio! of wear of motor!

Cam timing or tappet clearance? the wilder they get, the more sensitive they are to being put in correctly, and they need a lot more care and feeding, things like decent compression and spark...

Probly not what you want to hear, but my freind had a 1200 sedan with a stock as f**k
a12 (it had extractors) and i swear to god,
it got to "H" on the speedo!
Thats getting up round the 200km mark!

Quote:
I've read that to double your speed requires 4x the horsepower. This is due to the aerodynamic drag increasing by 4x.

Aerodynamic drag is a huge factor. I remember running next to an Acura Integra on the highway at 120mph (195kph) in the Chickenhawk. When he bailed out to exit, I lifted off the throttle. The wall of air slammed me back to 80mph (130kph) as if I'd hit the brakes!

do you have a frt spoiler on your car? if not adding one should be worth some speed by keeping air from under car and lifting frt end.

my engine is good, it starts to make power from 3000 to about 7000 surely it should pull away in top gear???? this motor has me by the balls!!!

again today 3 people in the car just over 140 in third put it into 4th foot flat and nothing at all, just watched my fuel level drop.

another question it did the same with the stock carb. SO NOW WHAT??????

AAAAAAAGGGGGGGHHHHHHHHHH

thanks guys
nicholas
south africa

if your car still has the stock emmission
controlls on it and the stock trans with
all the wires hooked up it will retard the
timing in top gear . I know this is true with
U.S. spec vehicles if not check your ign
timing and try again..
wubbits

The 1971 and 1972 A12 has no retard mechanism. I know that some of the newer US a-types engines do. Look for two vacuum ports on the distributor. If you have two, one is vacuum advance, the other is vacuum retard. You can plug the retard with no effect on performance.

Vacuum advance has no effect at full throttle ... and there is no limit on mechanical advance.

Some of the Datsuns have a top-gear switch on the transmission as Wubbits indicated.

i was thinking last night, could it not be the jetting? the stock carb had a 105 primary and 150 secondry, the webber now has 150 and 155, maybe it's too rich??

just a thought, what do you think??