Technical Oiling issues on Small Journal 327, no oil pressure at idle

Back in the day most engines started burning oil some where around 70,000 miles. Heavier weight oil and a honey type additive where used for a time. Eventually when the spark plug fouling and smoke got bad enough the engine was overhauled. So we did a inframe ring and Rod bearing job. The heads where sent to the machine shop and cooked and the valves lapped ect. And when reassembled the engines didn't smoke and burn oil. However at idle the oil light flickered. not changing the mains and cam bearings and the reuse of the worn oil pump. Added to the thinner oil without motor honey left plenty of excessive clearances for the oil pressure to excape. It was internal oil leakage. However those engines would run many thousands of miles with no appreciable oil pressure at idle.

 

I don't know why you would see a stream below the drain. Can you tell the direction it's coming from? Maybe remove the rear set of lifters and try to cover the oil hole with your finger while pumping oil.

 

Don't forget that 10# per 1000 RPM (hot) seams to work well for most SBC's.

I've seen some SBC rod and main bearings look pretty rough and not hurt anything. Even some oil pumps that looked like they ate rocks and they still worked fine. I have an 383 SBC (in my avatar) that ate a tablespoon full of cast iron chips and ran for 5000 miles before I figured it out! It scored all 8 cylinders, lifter bores and bearings, and didn't even smoke. Eventually I did hone it to .040 over, and it runs fine. 20# hot at idle, 45# at 2500 rpm and 70# at 5500 rpm.

I realize this is a new motor, do the best you can and look for the obvious, but don't get too out of shape over it. I'd put in the new hi-volume pump with a high pressure spring and see what it does. You can always change the spring back if you think it's too high.

 

If you look at the pic I posted, it is in the rear corner. It comes from the back of the block shooting forward. After talking with some other folks, it may be the passage to the oil filter. I'm looking at schematics to help discern what's what.

 

the rear cam bearing and its webbing direct the oil....this may be where the oil is leaking from........ .
Your housing for the primer must be shaped like a lower distributer housing or there will be leak as well.

 

Lost my subscription to this thread somehow so maybe this post will hook me up again.
Difficult to see an oil stream clearly in your pic, but I am wondering about proper positioning of rearmost cam bearing with a heavy stream of oil in the area you describe.

 

What it appears to be, is the return oil from the lifter galley.

Here's where I am . Pulled the lifters and the front timing cover, dropped the pan down loose to get the the timing cover out. Removed all lifters so I can get a better look.

In the first set of lifter holes from the back, there is a solid stream, if I cover that hole with my finger, the stream starts in the hole I posted pics of. The excess must just return to the pan when the lifters are installed. So I am thinking the cam bearings must be right.

Also, I can see oil seeping from the front main bearing and also dripping out of the forward cam bearing onto the timing chain, so the oil has to be making it that far.

 

I hope that's all it is and not a crack in the oil galley just adjacent to it. Crossed fingers.

 

It does it on both sides, so I am thinking it is by design. I think the pump may have been the original issue, but I am making very sure that every works as advertised. I don't have another removal/install in me this month.

 

That get's old real fast, even when you're young, I know, I chased some "issues" on the 355 in my first race car about 1975/76. First was a stuck bypass in a used Melling pump I bought (stuuupid idea), blew two oil filters off before figuring that out.
The next was a burnt up pushrod and rocker arm caused by a mfg defect, the insert in the end of one pushrod never got drilled. Lucky both got fixed before needing to pull engine.

 

One thing is for sure, I will be well versed on the oiling system of a SBC.

 

You said "produce truck". Do you have to pull the motor out to take the pan off?

 

Hey, it gets easier and faster each time!

 

Unfortunately yes, it hits the front crossmember. It's a 35 Ford pickup.

 

So, I did more more troubleshooting.

I pulled the lifters all out and ran the pump. I watched for oil flow and added a set of lifters in each set of holes, if it oiled, I moved to the next one until I was all the way at the front. Then it started oiling the timing chain. Both sides were the same. The lifters are also filling the cups where the push rods meet now.

I am thinking that this may all be ok now.

 

Do you think the roller lifters flow more oil (at less pressure) than flat tappets? Just wondering, I never had rollers yet.

 

Man, this is my first set of Hydraulic Rollers. I have no idea.

 

So I'm curious. Some race/performance engine builders will install oil restrictors in place of the rear plugs when roller rockers are used. I wonder if the hydraulic roller lifters are designed to do the same thing and are supposed to be used only with roller rockers. This could account for the reduced oil flow to the rockers that you see.

I gather you have standard plugs in the rear of the block. yes?

 

Yes, just standard plugs in the rear.

 

One more, I know you looked for the plug under the rear main and you said it's there but is it in the right position?

 

As far as I can tell.

 

I read on another forum you can stick a clean piece of welding rod down the gauge sender port and measure from the top of the plug to the top of the block and read about 8-3/8". I have never done this myself but it is another quick check.

 

It just seems to me that you are bleeding off too much oil but I've never looked inside while pressurizing the engine. Does it seem like much pressure to hold back with your finger when you had the lifters out?

We used a differential pressure gauge to monitor the difference in oil pressure between the rear and the front of the engine. It tells you in a hurry if a push rod breaks and a lifter comes out of the bore. There should be a port near the timing cover. I guess as long as the pressure at the front and back are within 5 psi you should be okay.

 

Keep in mind, I have changed the pump since all this started.
Also, see post #120 on page 4.

 

I understand you've changed to a stock type pump. I've use a lot of Harry Melling's pumps without problems but these days many things are outsourced so quality control can suffer. We always ordered the high volume low pressure version. It seems that they've combined part numbers by including a variety of relief springs. The high volume helps mostly at lower speeds. Racing engines typically operate at higher speeds than stock so the stock pump provides more than enough volume. Sometimes it takes a while for hydraulic lifters to fill with oil. Usually running the lifter a little loose causes it to pump more oil before tightening it to the final setting.

Oil, like everything, does heat up as it is compressed but we aren't dealing with extreme pressures so no extreme heat. Many hydraulic systems use a pilot or servo pressure system to control valves. Many use 1000 psi and it is controlled by a relief valve.

I hope you have the problem solved.

 

Retrofit roller lifters on early blocks can cause oiling issues if the lifters come out of the bore too far, uncovering the oil ring on the lifter and a large loss of oil pressure. Kinda like what you have going on. Just thinking out loud.

 

What was the rod and main bearing clearances? Lots of clearance= low oil pressure.

 

I can't remember exactly MrHP, but I wanna say they were right in the middle on the tolerances when I plastigauged it all.

On the last round I used a new battery on my cordless drill and we had 35-40 lbs on both gauges.

 

I have my doubts that's good enough. Your pressure is with cold oil, engine, and pump. Once things are at temp, the pressure will drop.