just curious if anyone has had any sort of vibration from about 5000rpm onwards. it feels like a resonance vibration. the motor has done 3000 km since rebuild. the motor was balanced when built, head ported, 30 70 cam, higher comp ratio. the su carbs and manifold really start to buzz and vibrate, I can feel vibration through the pedal and on the floor pan and fire wall of the ute. any help or info would be appreciated.

has it allways done it or just lately

double check that the harmonic balancer is tight. i had one come loose once and it made the engine vibrate badly before it fell off and caused an electrical problem when the piston damaged the starter motor

i have just noticed it now becouse i have put in richer needles, it wouldnt rev past 5000 before.

i just looked on my crankshaft pulley and can't see any thing that might be a harmonic balancer. do all engines have them

Nissan A engines do not have a harmonic balancer, only the crankshaft belt pulley.

It is normal for a four cylinder engine to have some vibration. But not a lot.

Take the needles back out & put the original 1,s back in &see if it goes back to normal eg no vibes! If it would,nt rev before my guess is it was too lean an even though now it revs further it may still be lean, fatten it up more an see what happens.. Most motors run lean sound harsh and reasonant prob cause they,re near detonation levels.. Juz my 2c worth.. Have fun sort,n ya beast!!

got to get it dyno'd to see the air fuel ratios then can see how if its running lean or rich. took it to the engine builder today anyway and he didn't seem to concerned. It seems to vibrate a bit less under full load. Might try to keep the revs down till dyno, let you know how i go.

Try advancing / retarding the dizzy timing

Can't you give an example of some general item that vibrates in the same manner as your engine? Example an electric drill drilling a piece of metal or drilling a wall on normal drilling action or drilling a wall on hammer action. This can give us an indication how serious the vibration is. I know my standard A12GX motor is not balanced and it has some vibration.Not very bad.Feels like a drill that is drilling into a wall but not on hammer action, just normal drilling action.Hope you know what I mean.
I must admit that this is at 6000 to 6500rpm.

I own a 2004 Nissan Almera. 67 000km on the clock. It also has engine vibration when going past 4500rpm.It's about the same as the Datsun.