[383ram]

I bought a 454 the other day, and upon taking it apart, i noticed the upper rod bearing shells are just down to the copper on the mid section, the bottoms are not. The mains seem fine, but are worn pretty evenly on both halfs. Is this an indication of some type of problem with the rods or crank?

I have no idea what kind of mileage is on this engine, its an '85. It has been rebearinged once before (had clevite '96 date coded brgs in it--all std size), i am guessing its been decked too as the numbers are gone off the front machined area. It is still std bore. To be honest, it looks like some trash went through the oil system, the crank surfaces are still smooth, but have that look like it was riding on trash in the oil---maybe a quick polish job will fix that.

Also, are there any tricks or mods for oil system modifications? I use to build Mopars and there were certian tricks we used to do for better oiling. The main reason i ask is it seems alot of later 80's on up big blocks i see listed for sale always have lower end knocks.

Thoughts?

 

[cobaltchev67]

High volume oil pump, high pressure spring with restrictors in the block to prevent tons of oil going to the heads and staying there would be a couple of ideas. Remove casting slag from the lifter valley drain back areas to help oil returning to the pan. Have machine shop cross drill the crankshaft and chamfer the holes. Make sure there are no leaks from galley plugs...threaded or soft.

It sounds to me like low oil pressure and maybe dirty oil....lack of oil or filter changes frequently. Some people buy synthetic oil, change it at longer intervals but what they don't realize is that the oil still gets dirty no matter what the advertized life of the oil is. Chevy made a good oiling system, just make sure it works properly.

 

[BillK]

Chad,
The upper rod bearings take almost all of the pressure everytime the cylinder fires. Any detonation makes it worse. As far as oil system modifications, you really should not need any. The Big Block (and small block) oil system is about as bullet proof as it can be just like it comes from the factory. If you like to see high oil pressure for some reason, use the Melling M77 pump and install the blue spring that comes in the box with the pump. There is no reason for a high volume pump etc. Maybe when you start making 800 hp or so, but not till then.

Just for example, I just freshened up a Mercruiser 600sc (supercharged) 502 that dropped a valve seat. All it had was the stock Mercruiser pump which is a Melling M307 (std volume, special high pressure) pump. It had been running for 9 years (close to 300 hrs) and showed very little wear on the bearings. Mobil 1 15W50 oil. This engine probably makes around 700hp and is under full load any time it is running

 

[GuysMonteSS]

You do not want to use restrictors when you do the rebuild,heres a link you may want to read through,take Mike "Wolfplace's" advice;
http://www.chevelles.com/forums/showthread.php?t=158046
One thing you can do is to drill 1/32 holes in the oil gallery plugs that are adjacent to the front cam bearing.,These holes will help to bleed air from the oil gallery's,lubricate the timing chain & cam timing gear thrust face.Its also not a bad idea to plug the oil filter bypass,this will help ensure that the oil is filtered better.If you do this,just let the engine warm up a bit before you get on the go pedal.
Guy