Bubbacuda68
Member
Has anyone come up with a solution for the weak intermediate oil pump shaft on small block, 68-340 to be exact?
I did investigate this same thing years ago and it was said then that pinned shafts are weaker.It's been argued that the pinned shafts are weaker than the pressed on and I can see some validity to it. The hole drilled through the shaft to accept the pin can certainly be a weak point.
It's been argued that the pinned shafts are weaker than the pressed on and I can see some validity to it. The hole drilled through the shaft to accept the pin can certainly be a weak point.
I've seen that as well. That's why the "good" shafts don't have a hard "step" there. The goos ones look like this. Without the pin, of course. But you know that already.If that’s where the failure is. Most of the failures I’ve seen the drive fractured at the neck down to the hex drive.
I did investigate this same thing years ago and it was said then that pinned shafts are weaker.
I've seen ONE break at the gear end where the pin is. It wasn't mine. It was on a big block. It had much the same shaft as the one I pictured above. That's the only one I've ever actually seen.I should have asked RRR too (he can read this and answer too) how many of these failures have you seen at the drive gear end?
I know I’ve run as high as 125 pounds of oil pressure and never failed a drive.
I also gave a theory about bronze gear wear. IMO most of the bronze gear failures are because cam thrust is not verified and corrected.
If it’s not corrected the cam can move enough that rapid gear wear occurs.
I can’t count the number of times I’ve had to machine a cam gear to tighten up cam thrust. Almost half of the builds have the thrust too loose.
Right where it goes from round to hex.Where does it snap, near the oil pump end ?
Tommy
Yes, the oil pick up is used but the pump is a new HV pumpI'd be scrutinizing the oil pump/gears for evidence of whatever is jamming the pump.
Once is an anomaly, twice is not.
Used oil pick-up?
That is where both of my failures were, at the neck down where it goes to hex.If that’s where the failure is. Most of the failures I’ve seen the drive fractured at the neck down to the hex drive.
That is where both of my failures were, at the neck down where it goes to hex.
Yes, the oil pick up is used but the pump is a new HV pump
It looks exactly like the post in 12
I hHow much pressure is the pump putting out,,,,,unless it’s over a 100 pounds , you shouldn’t be able to break a shaft,,,not a good one .
Tommy
This is a fresh build, pick up is used but CLEANED through and through. New bushing, oil pump, etc.Is this a fresh build, or a running engine.
You wouldn't believe the debris that'll come outta a used pickup while banging it on side of the solvent tank when cleaning .
A little background will help .