I've been reading on www.impalassforum.com lately about heads/cam swaps and that a bunch of the Impala guys have had crank bearing failures after swapping the heads/cam because the stock pump doesnt work well at high RPMs.

Have any of you guys had this problem??

I also read that the problem wasn't the pump not handling the higher RPMs that it was because the pump was starving the crank at high RPMs.

Any truth to this?

If this is true, is there an oil restrictor out there that could be used? Or what can be done to combat the starved crank besides a new pump/pickup?

Thanks

 

First off, don't use a oil restrictor on a street motor unless you want the thing to break stuff on the top end of the motor.

The bearing failures on most head/cam swaps is due to dirt in the bottom end, not lack of oil.

You can't starve the bearings at higher RPM unless you run out of oil in the crankcase.... We don't have huge main bearings like a old Pontiac V8 so thats not going to be the problem.

Bret

 

Been quite a bit of discussion on this, Try searching and you will hear alot of opinions.
My take on it would be, taking the Motor to Higher RPM's it wasnt meant for, And being careless when doing the swap and getting junk into the oil pan, or into the oil......
Use caution and be careful....Be clean!!!

 

While youre on the impala forum, check out Karl Ellweins stuff & his website... He pretty much only uses stock oil pumps on all his engines...


http://www.karl-ellwein.org/

It's not the stock oil pump. (unless there happens to be something wrong with it) Most likely the problems are created during the installation process, or the bearings were in poor condition to begin with.

 

do you reuse the stock oil restrictorr? The little ball in the oil galley between the rear main and the oil pressure sensor. I had planned on putting the ball back in. I thought gm used the ball to determine the flow rate instead of machining the hole to the proper size.

Jason Robb

 

Jason,

You have to put that back in the block because that runs the oil thru the motor the proper way, it's not a restrictor. That ball/plug is in there so oil goes thru the filter and the engine will have the proper oil pressure.

Bret

 

SO if I spend a little change and get the melling pump and pickup just to be safe then I should be okay with just doing a clean install and changing the oil often after initial start up.

Say run it for a minute or so then change the oil and filter, run it for a day or so and change it again, then run it a week and change it again??

 

It only takes a(1) piece of trash the size of a grain of sand to get under the pump relief valve to kill the pressure.
IMO a lot of the problems with LT-1 brgs is the quality of most of the factory brg's.They were installed to run in a stock engine and no cushion for any extra abuse(cost factor) and they won't take the extra load and RPM's.

 

You're bound and determined to get and use a pump other than the oem, aren't you, whether we agree, or not. Well, then go for it. The oem pump has been used effectively for decades. The oem pump has seen rpms higher than you will turn, and the sbc is easy to oil effectively, compared to other mfrs. of V8s.

 

I've used melling and stock. You will be fine as long as your clean on the install and don't run the **** out of it. Think, most people get in the new cam and wanna see what the potentiol is. Beat the motor and ruin the bearings. Most engines have 80k plus miles on them anyways. 80k mile bearings meeting brand new virgin cam means things have to mate to each other. More wear.

-Shannon

 

[QUOTE=NOMAD]I've used melling and stock. You will be fine as long as your clean on the install and don't run the **** out of it. Think, most people get in the new cam and wanna see what the potentiol is. Beat the motor and ruin the bearings. Most engines have 80k plus miles on them anyways. 80k mile bearings meeting brand new virgin cam means things have to mate to each other. More wear.

By rights the cam should be turning on a cushion of oil. If the brg material can't take the extra spring pressure and RPM's they flair out leaving more clearance and less oil pressure.The bottom end is seated all it's going to @20.000 miles. The brg quality is such that a stock LT-1 can't take the extra abuse.Just like anything you buy today it is built to last doing a certain job (and will) and no more. When you put more pressure on it,KABOOM. Two oil pumps won't keep the brg material from failure and opening up the clearances and spun brg. Seen it a number of times with customer engines.

 

damnit, i think i lost mine! where can you get those...and what are they called?

 

If unable to get the ball, the readily available 'cup' plug, of same diameter, is very suitable. The reason for the necessity, to plug the hole, is due to passage being used as access, to drill necessary oil passage further into the passage, that after the drill procedure in machining center, now needs plugging. It's tough drilling around corners, or in a curve.

 

so, does anyone know where to get this ball from?