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

Wil do. I figure I'll just eliminate the problem totally, then if it fixes it, I'll do a tear down report.

 

Not to be pedantic here, but a Z28 spring is not standard on a small block. The standard spring on my '67 L79 is rated at 47 pounds. BTW, every Mellings pump I have seen (3 or 4) had a high pressure spring installed at the factory.

 

Remember we are talking VOLUME here, not PRESSURE. Many people are confused about this. The volume depends on the length of the gears in the pump, and the pressure is controlled by the relief spring (except in the case of engines with overly large clearances).

 

Not too bad of an idea

 

What brand of Oil Filter is on the engine Chris?

 

I think your on the right track changing the pump. I did read something about these HV55 having all sorts of issues back around 2011 or so. I've personally never had drain back issues with high volume pumps and have also run BBC pumps in SBC's. Let us know what the out come is.

 

You said it pegged the gauge the pressure should get no higher than the relief valve setting. When you rap the engine and the oil pressure quits climbing you have hit the relief.

 

A '67 L79 has a 60 lb gauge. Generally, only the solid lifter cars had 80 lb gauges.

The only reason I got into this is to let everyone know, that contrary to my "signature", "Too much is just right" does not pertain to oil pressure. Also hi-volume oil pumps should only be installed in racing engines with larger than factory bearing clearances. If you have one in a basically stock engine, change it out. (Anyone with an engine with more than 150,00 miles is exempt from this last bit of advice.)

 

That's it. We run one our 374" 1/2 mile dirt car engine.

 

It's a Napa gold.

 

Hope you find the issue soon. Have two small journal 327's here-both run 35-40LBS at idle warm and about 60 down the road. The one in my wife's 55 has run that way since 82 with no issues. Both have spinon conversions, Napa gold filters now and Brad Penn oil. Both have fairly mild hydraulic cams as well.

 

The cam bearings on a small block chevy don't need the oil holes aligned with anything. there is a groove completely around the block side of the bearing. The oil hole only needs to be in sync with the groove in the block. The oil holes in the cam bearing only oil the cam journals. The chevy cam bearings must be installed on the specific journal . they are numbered and each has a certain position. The chevy cam bearings have nothing to do with oil to the rocker arms or lifters.

 

I see you ordered a new pump and pickup. I not saying the pickup is the problem, and I'm sure you are aware but the pan decides the pickup not the pump. I knew of a guy that welded a pickup and had a pin hole in the weld that sucked air as well as some oil, starving the engine, took a long time to figure out.

 

Another thing about that very thing. I've had a Hi Volume pump that was stated as only Hi Volume and when I opened the box I discovered an extra pressure spring included. Turned out that was the spring for only Hi Volume and was set up as Hi Pressure also. One has to inspect everything and never assume anything.

 

Yeah, I agree. I measured the pan rail to the bottom of the pan. This one is welded to the pump. I doubt I will weld mine.

 

Not on early motors no groove.

 

This is a 67 SJ. It has the groove. It was out of a 67 C10 my father in law bought new. The truck got totalled a few years back, so I kept the motor and tranny out of it.

 

When the block was machined ,were the oil galley plugs removed? A good shop will remove plugs and rifle brush the oil galleys and the replace the plugs. Also if new cam bearings were installed the might have been put in wrong and covered the oil holes. I know you don't want to remove the engine again, but a teardown now would be cheaper than a full rebuild. Also you only nead a stock oil pump

 

I'm going to refrain from getting into the high volume vs regular oil pump discussion because it isn't the issue in this thread, but I'm very interested in the outcome of this issue.

 

You and me both.......

 

If the cam bearings are put in wrong It still wouldn't effect oil pressure. it would burn & score that cam journal from lack of oil. The cam bearings only have to be centered in the journal and installed in the correct positions. Ive heard about installers having to scrape or alighn hone the cambearings. I use a bushing driver from a auto trans kit to drive in cam bushings. Mine is almost the same tool squirrel used on his 292 ford. And ive never had a camshaft that didn't fit. Now possibly someone scraped or in some manner altered the cam bearings and they are leaking excessively. That would cause a oil pressure drop and a internal oil leak. that's why I suggested a leak down test in a previous post.

 

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I installed the cam bearings using the correct driver. I even went to the extent of clocking the bearings at 2 oclock as recommended in one Hot Rod article I have read. The bearings were nice and smooth and the cam rotated by hand freely.

 

I have an Edelbrock SBC Signature 460 in my delivery and it does the same thing at idle. I called Edelbrock and they told me that is for better oiling than a high pressure pump??? I have been driving this engine for over 7 years and it still works great. I don't understand why but would like to know. The pressure rises to 25-30 at 70 mph. My concern has always been the idle pressure. I have tried racing filters, and other brands but the result is the same. Any suggestions would be appreciated.

 

I pulled the motor, because I love doing that, and I have so much free time....
So I flipped it over and pulled the pump. Nothing visible. Haven't driven out the pin on the relief valve yet. Started mocking up the new pump and they sent the wrong pickup. I found one across town I am heading after. Pulled the rear main cap and looked down the passage, the soft plug is installed. So I guess I will install the new pump, the pan and service up the oil level and spin it up, see if I get oil pressure.

 

Just to clarify, pumps provide flow, not pressure. Pressure is a result of resistance to flow. If there is no resistance to flow there will be no pressure. Pressure is "controlled" by the relief spring only in that the spring will open when the pressure exceeds the strength of the spring. This should only happen sporadically, like during high rpm's when the oil is cold, not all the time. Pushing oil past the relief valve causes it to heat up drastically. If the volume of the pump was so great that the supply (flow) caused the oil to run over the relief valve all the time, you would have serious heating and degradation of the oil. The pressure is normally controlled by the amount of flow and the internal resistance in the engine, which is determined mostly by the clearances.

 

My point, exactly.

 

See my post above. Pressure is always a result of resistance to flow. There is no getting around that, that is the physics involved. Pumps provide flow, resistance to flow results in pressure.

You may have a case where the clearances in the engine are great enough that the supply from the pump is insufficient to build more pressure, or you may have a weak spring on the relief valve, causing it to open early, which will cause heating and degradation of the oil. If it's the former, I wouldn't worry about it, as Old Wolf posted earlier, higher pressure does not equate to longer life. (sorry guys, it doesn't) If it's the latter, that's not so good.

 

While you've got the pan off and the engine upside down I think it would be smart to use a feeler gauge to check the side clearance in the rods.
Pete

 

So oil sqeezing past the relief valve heats up but oil sqeezing through the clearences in the engine doesn't?