Spun bearing problem, again

[DisturbedCamaro]

I've got a 3.1 in a camaro that is modified quit a bit to allow a turbo install later. This is the second time that I've spun multiple connecting rod bearings. I don't push the engine hard and keep a very close eye on the oil level and pressure. Both times I started hearing that hard knock that will get worse quickly. The first time I didn't give in to the rebuild until the oil pressure dropped, the second time I caught it before the oil pressure dropped. The last time out I had the machine shop check everything very close and I checked as much as I could when I got the parts back from him and assembled the engine. This included balancing and getting a new flywheel and damper. Anyways has anyone else had this problem or does anyone have any suggestions. Here's a list of some stuff that has been done.
bored 0.030" over, ross racing pistons, 8.8 compression, crane cam, 1.6 rockers, GM HD valve springs, cloyes double roller chain, intake and heads ported & polished, accel injectors.

[geoffinbc]

Sounds like an oiling problem with the bearings. Were the oil passages cleaned before installation? Are you using the proper bearings? A shitty bearing may have the oiling holes in the wrong position. I would asume that when you and the machine shop checked the bearings you did do a plastiguage check or used a bore guage.

[DisturbedCamaro]

The first set were federal mogul tri metal series, the second set were the new a-series federal mogul which were just released and are bored out of a solid stock of aluminum. The bearings were cleaned before installation, and I know the oiling holes were there but I don't think they were in any different position than the factory ones. Any other suggestions, I'm thinking about getting a new set of rods.
Thanks for the help

[paulo57509]

After the bearings spun the first time, did you replace the rods or have the bearing bore resized?

Once bearings spin be it main or rod bearings, the bore where the bearings sit usually get bigger and don't crush the bearings enough to hold them i place.

In the case of connecting rods, some material is removed from the cap and rod faces. The cap is then installed and the hole is bored/honed round again.

New/reconditioned rods is a good idea.

[geoffinbc]

You need to check that all the oil holes in the block mains and rods are all clear of blockage. If they are blocked you will still have full oil presure on the guage but no actual pressure to any part after the blockage. Also the lifters used in the upper end of the block may be an issue. Remember the crank gets oil after the lifters. If the lifters are not machined correctly they may be restricting oil to the bottom end.

[bjornmk1]

oil channels

hi guys,I'm new to the forum,so this is my first post

i'am in doubt about the v6 oiling issues..


correct me if i'm wrong...butt my 3.1L(89 alu heads) has it's own oil feed channel to the crank.(no feed from the lifters)

the 2.8L doesn't ..right?????(gets it feed from the lifters)

thanx.bjorn

[3100 MPFI]

This might sound a little weird, but what OIL PUMP are you using?

Lorenzo (GPSE3400) put a HIGH VOLUMN oil pump in his 3400, and it was actually sending all the oil up top, and there was not enough oil in the PAN, so he developed a knock.

You problem could be that your oil pump is overpumping, and not keeping enough oil in the block.

[sharkey]

i have never had the issue of to much flow. i run a mellings high volume pump.

something to check would be the pump pickup. ive seen were they are to close to the pan and end up sucking the pan up, starving the motor for oil. another thing would be to get the rods resized, and make sure your cam bearings are in with the oil holes lines up to the block.

the gen 1 and 2 blocks, including the 2.8l ironhead, 2.8l mpfi, 3.1l ironhead, 3.1l mpfi and 3.4l sfi ironhead (f-body) do not have priority main oil feed, only the newer 3100, 3400, ect have that.

[bjornmk1]

oiling issues

ok,that cleared me up.

thanx

[gpse3400]

A GEN1-2 block might just work better with an HV pump, but Who was it colin having oiling problem with HV pumps too? I don't know what motor he was using....

I had a '94 Z28, similar oiling system as the GEN3 and I tried an HV pump in there, used to get erratic pressure readings at WOT not to mention it wore out my drive. Fortuntely I didn't use it that long.. Actually got some response back. When I ran the HV Pump in the 3400 I never really noticed a gauge fluxuation (maybe due to the loctation of the sensor) but I almost wore out the drive...Not to menton all my lower mains and upper cons were washed away. That was a reman crank I had in there. I used to wind this motor up to 7200 RPM the oil pressure would be sky high, a tick below 80 if not that. Way too much pressure for a priority main engine that does fine on 40. The TDC although priority main, I think is calibrated very differently than the pushrods, where there a bit more oil control for the mains.

i have never had the issue of to much flow. i run a mellings high volume pump.

something to check would be the pump pickup. ive seen were they are to close to the pan and end up sucking the pan up, starving the motor for oil. another thing would be to get the rods resized, and make sure your cam bearings are in with the oil holes lines up to the block.

the gen 1 and 2 blocks, including the 2.8l ironhead, 2.8l mpfi, 3.1l ironhead, 3.1l mpfi and 3.4l sfi ironhead (f-body) do not have priority main oil feed, only the newer 3100, 3400, ect have that.