Quote:

No, at 120 or even 140km/h there is no noticable vibrations. Nice and smooth.
At 140kmh the exhaust is just really making alot of noise.
I think it is because there is now lots of road noise and road vibrations that cancel out the engine.
But like in a drag race situation when you drive it hard in first and second gear the car is low in speed so vibrations from engine are picked up easily.

Hi all

Good news.
I found the problem. I took my car in for a tappet ajustment because one tappet was making a bit of noise for some time.
When I got it back. The mechanic informed me that ALL tappets were too tight and one was too loose.
He ajusted them correctly. (This is the mechanic who helped a Datsun racing team in the early 80's. They raced a 1200GX).

I also discovered that my tappet cover breater pipe was blocked due to a sharp bend that made the pipe colapse and shut if off. I replaced this pipe. And very important. I went to a exhaust shop to put on a 2" freeflow exhaust as mine started to make some strange noises from the box.

Through investigation, the exhaust box that was removed was starting to cause blockage inside making it difficult for the car to breath. The engine made alot of noise when revved hard past 5000rpm and it also struggled to rev to 6000rpm.

The results.
Car is now as silent as a mouse.
I can rev it to 6500rpm without noise coming from the engine asif someone is strangling it. And it is much smoother than it was.
I cannot believe that such stupid stuff could have caused the problem.

I also discovered that the vacuum advance pipe was cracked near the distributor.
So bad that I doubt there was any vacuum advance taking place. This pipe I have replaced and must still test if it is going to make a difference.
Does vacuum advance make a big difference?

Keep that mechnic......tight valves will burn up if not corrected. I always err on the loose side.
Plugged exhaust definetly explains why it wouldn't rev!!!
It doesn't take much to get an engine running way off, it will still run but not well. You should see what 1 degree of dwell to many does to our old Ford truck.
Anyway glad to hear you car is running sweat.

Tom

Quote:
No vacuum advance AND a vacuum leak. With that repair you kill two birds with one hose.