Our Datsuns suffer from a harmonic problem with the stock pulley when revs start reaching five figures, & this is when flywheels come loose [or off] but a different pulley will change this situation.

I think that it might be an idea to talk to someone knowledgable in this area as I don't know if this will move the self destruct point further up, or further down the rev range, or by how much, but it will change it.

A local racer runs a heavier, harmonic balancer, & his flywheel loosening problems have ceased to exist since fitting it, but we don't know if this is due to the extra weight, the rubber mounted balancer weight, or a bit of both.

doesn't making the flywheel lighter help with that harmonic thing too?

YES CAPITALS IS CLASSED AS YELLING so if you please dont yell i have sensitive ears

smaller crank or larger alt same result i run a fairlane bosch , me big pulley

dodgeman I'm thinking higher in the range , can i phone a friend

dont mind me 4.42am having beers after work
cheers

Yes well thanks all i will take all your input and hopefully make a pully we all will buy...dodgeman has a point and dattoman1000 has pointed them out to me as well...but from what dodgeman says we have to be reving into 10000RPM range to do damage i know my motor wont be reving there at all or do i have it all wrong?
If you are interested i would like a pm to get some official numbers so i can get a quote....

Thanks all for your input.

What brings us undone with the flywheel is a max RPM revout in second & a flat shift to third, ..... & missing it. That'll do it just about every time. Quite often the original pulley will also split along the keyway & at least one member has reported this pulley coming off the engine completely.

There are more than a few on this site who can give us some stories about loose flywheels.

just some food for thought i had a alloy frount pully made recently under driven and with an extra lip to mount my crank angle sensor pins in and was able to find a seal with the same external diameter as the timing cover but with about 5mm extra id size this enabled a much thicker piece to press onto the crank

Great move & really good thinking.
Now all you need to appease the rest of us in our thirst for knowledge, is to come up with some details of that seal, like part number &/or the application it was originally used in.