distributor drive failure

[steve g]

Hello,

me and 2 of my best friends own 720 pickups, we have built several motors over the years but we are now in total loss from whats been happening.

the three of us are very mechanically inclined but there is something we are missing here.

 

The last 2 z24 motors we have built have exploded the oil pump drive gear... thank god the second it happens the engine shuts off because the distributor stops too..... but whats causing this? this is twice in a row now.

the first motor blew 2 drive gears, the last motor is sitting as we scratch our heads.

Any help will be greatly appreciated.

Steve

[datzenmike]

Is the oil pump or distributor seized or tight? Are you using the same timing cover both times... maybe it's worn and the spindle is wobbling?

[datsunaholic]

I've seen this before, just not on Datsuns, when the wrong thickness gasket was used at the oil pump. But the Datsun uses a worm gear so that alignment isn't critical. So the only thing I can think of is something got in the pump and siezed it, which sheared the drive. An autopsy of the pump might be in order.

[steve g]

the pomps were ok. i took them apart on the first engine to make sure there was no metal in the pump. still lost........

[jhoski]

This is one of the subtle differences of the L series motors. There are 2 sizes of drive and spindle gears. They will always go together, however will fail if mis-matched. This happens exactly the way you describe. The drive gear explodes. You probably had a large spindle gear being used with a drive grear for a small spindle gear. You should try and keep the spindle and drive gears as matched pairs to be safe. The factory used matched pairs when they originally built them.

 

I've had this happen too and it took us lining up several spindles to finally see the difference.

 

I ran across your post because I'm trying to sort out which years used which sizes because I just picked up an L28 stroker that did not come with a drive spindle. You cannot just drop any Z spindle in and I havn't confirmed yet which years are which.

[steve g]

This is one of the subtle differences of the L series motors. There are 2 sizes of drive and spindle gears. They will always go together, however will fail if mis-matched. This happens exactly the way you describe. The drive gear explodes. You probably had a large spindle gear being used with a drive grear for a small spindle gear. You should try and keep the spindle and drive gears as matched pairs to be safe. The factory used matched pairs when they originally built them.

 

I've had this happen too and it took us lining up several spindles to finally see the difference.

 

I ran across your post because I'm trying to sort out which years used which sizes because I just picked up an L28 stroker that did not come with a drive spindle. You cannot just drop any Z spindle in and I havn't confirmed yet which years are which.

Thanks for the info! this is one i have never heard of before but i will look closer next time. The z24i also uses a different drive gear than the others also. but luckily the distributors wont swap with with an older carb engine.