articfriends

iTrader: (1)

I'm posting this thread to help out some of you guys who are having serious oil pressure problems. I see guys on this bd alot asking questions about oil pressure issues,oil temp issues etc,i'm going to show some potential problems that might be causing alot of your grief.I am not a expert by any means BUT I have had the same problems and questions when i started modifying my original gen 6 502 5 years ago. Your oil systems need to be "optimized" to make your motors live,it will cost you a few dollars BUT do you really want to be rebuilding your motor twice or missing valuable boating time? A stock 502 or 454 has a tiny oil cooler and tiny fittings thru out the stock oil system.When your motor is still original everything works ok because a stock motor has very tight rod and main clearences (under .002) and has a std volume oil pump. The average guy builds up his motor,rebuilds a blown up motor or finds another motor and builds it up,typically you end up with rod and main clearences around .0025-.003. Sure,if you can find a super high quality machine shop that can hold tolerances perfect you could run things tighter but typically those clearences are what you end up with. The first thing you have to do is run a high volume oil pump( yes,everyone knows this) but heres where the problems start-if your running a gen 5 or 6 block and it started life as a crate engine,it has 11lb bypass relief valves. If your motor has unknown origin,who knows what it could have. Buy a new 30lb bypass relief valve for the outside(the one near edge of block casting for filter adapter) or plug it off,they are available at your local chevy dealer part #25013759,they are under 5$. The middle valve directs oil to the cooler fittings on side of the block that are not used in boats,leave it out completely. These valves open from a pressure differential,if your high volume pump puts out enough gallons per minute of oil to pump lets say 8 gpm and create 75 psi and your stock system will only flow 6gpm at 55psi then your block bypass will open and your oil will not go to your cooler and filter. Your motor will then get unfiltered hot oil. The new 30 psi valve will help to prevent this from happening.

articfriends

iTrader: (1)

The next thing you need to do if running a high volume oil pump,looser clearences and more horsepower than stock-TAKE A GOOD LOOK AT EVERY FITTING,ADAPTER AND LINE in your oil system. Most likely you need to completely replace all of it. The stock merc stuff for a gen 6( and probably gen 5) is JUST TOO SMALL.Here is a example-the stock gen 6 block adapter has a .390 dia discharge hole-THAT IS BARELY 3/8's of a inch. Just to show you what i mean i stuck a 3/8"s bolt thru the hole in 2nd pic. Even with a 30 lb block bypass valve it is so restrictive that you could still make the bypass open or worse,make the regulator on the pump open in the pan reducing your output and causing low oil pressure.

articfriends

iTrader: (1)

There are several afternarket companys selling block adapters and remote oil filter mounts. This is a pic of a old one i had on my gen 6 that cp performance sells compared to a stock one. The discharge hole is almost 5/8"s instead of 3/8"s.

articfriends

iTrader: (1)

The stock filter adapter is no better,here is a pic of a aftermarket one,i couldn't find the stock one to compare it but it has the same tiny hole that the block adapter has.This one uses -12 an fittings with big high flow passages.

articfriends

iTrader: (1)

OIL COOLER-your stock oil cooler on most gen 5/6 blocks looks like this,smaller dia then a beer can with tiny .390 dia pasages where fittings screw on .You can see from 3/8"s bolt in the hole how restrictive it is.When your motor made 415hp it was barely big enough,now your asking this tiny cooler to cool your oil,its not going to do much. Buy a aftermarket cooler,they are much bigger than stock,will actually cool your oil and will allow you to get rid of all the factory oil lines and fittings.

articfriends

iTrader: (1)

Oil lines-the factory oil lines have tight radiuses on them and inverted flare fittings that only fit your factory adapters and cooler. They are as small as 3/8 inch id also and canot flow as much oil as a high volume pump can put out. Preferably you should run all your oil lines in -12 an(rusell,aeroquip etc),it is generally 5/8"s id and if you have to use alot of 90 degree fittings or adapters your smallest adapter will be at least 1/2 inch id. You want to run your oil lines as short as possible with as few bends,turns and adapters.If your factory oil cooler is on the opposite side of motor from where your block adapter comes off,move it. My gen 6 had about 12 ft of hose from factory to reach the tiny stock oil cooler. Every 90 degree fitting and tight bend increases the amount of restriction to oil flow. Avoid hydraulic hose with high pressure ends from industrial suppliers,if you look carefully at the fittings the adapters and ends often neck down to less than 1/2 inch,even on 5/8" or # 12 hose because it is so heavy duty to give it the 4000 or 10,000 psi rating.The proper way to route your oil lines is go from discharge on block(outside fitting) to filter inlet on (which is ouside ports on filter)filter adapter to oil cooler back to center fitting on block adapter. If you spin a rod bearing or chew up parts in your motor replace your oil cooler or have it professionally flushed,squirting carb cleaner or dumping paint thinner thru it and blowing it out is not good enough.Don't trust some flunky at the local marina to do this for you if they are installing your motor. There are tiny pasages that can trap metal and it will get loose later and wreck your new motor.

articfriends

iTrader: (1)

Last,run a high quality,high flow oil filter. I run a K&N high flow filter or a fram hp series race filter. The flow ratings of these filter exceeds what the oil system can flow so it should never be a restriction. I mounted mine so i can put a coffee can under neath it when changing oil so oil doesn't run everywhere.You can see it to the right in the picture. I hope this info helps some of you guys out there that are struggling with oil pressure issues. If i left anything out feel free to add it,Smitty

Lmarth

Great job Smitty!

KNOT-RIGHT

Nice informative thread!


Gerry

29scarab

Way to go Smitty!

I been running 250 to 280 oil temp on my 502mpi Whipple motor when running long distances. I think I need to go the route you have taken on this issue.

Thanks again!