Oil Pressure on gauge but no oil at valve rockers 427

[Ted K.]

Recently had an intake valve stick and make contact with a piston bending the valve on 66 427/425 with 3-4000 miles since complete rebuild. Took it apart replaced valve, reassembled motor and before putting on valve covers and adding antifreeze started it up just to see how I was doing. Started right up, ran it for less than 60 seconds and saw no oil flowing from push rods onto rocker arms, dry. Oil pressure at gauge was 60 at idle and with additional rpm more than 80. What has happened. Why no oil on top end? Thanks

[Duke W.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

'65-'66 big blocks require a camshaft with a groove in the rear journal and a "three-hole" rear cam bearing; '67-up use a camshaft with no rear journal groove and a single hole bearing. Many machine shops may not understand this. There are lots of pictures in the archives and explanations of the two different oiling schemes. Use of the later parts in the these early blocks usually results in little or no valve train oiling despite proper oil pressure gage readings.

If you had a "complete rebuild" the cam bearings and camshaft were likely changed.

What parts were installed? A manufacturers/part numbers audit of what was installed may hold the answer.

Duke

[Ted K.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Unfortunately rebuild was done before I owned the car. No records. I know the car was driven at least several thousand miles over the past 5 years, hard to believe with minimum lubrication. Is the lack of lubrication just on the top end? Does it impact the cam also? Is there an easy fix or does it require pulling the cam? What happens if I continue to drive as is? Thanks

[Bob H.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Isn't there a special groove in the dist as well?

[Michael G.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Isn't there a special groove in the dist as well?

I'm sure someone will verify my comment, but believe as long as the grooved cam was used adequate oiling was provided......and one could use either distributor housing. Partial grooved or grooved completely around housing.

[Wayne M.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

There's a lot of opinions out there on this subject. Here's from a 1972 article in "How to hot-rod BB Chevys" book. (left column)




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[Duke W.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Unfortunately rebuild was done before I owned the car. No records. I know the car was driven at least several thousand miles over the past 5 years, hard to believe with minimum lubrication. Is the lack of lubrication just on the top end? Does it impact the cam also? Is there an easy fix or does it require pulling the cam? What happens if I continue to drive as is? Thanks

If the engine was run very easy, I suppose it's possible that the valve train could live with little oil for a few thousand miles. The stuck valve could have been a result of insufficient oil.

Recommend you remove the rockers/balls/pushrods and carefully inspect them (use a magnifying glass with intense light) for excess wear or galling. With sufficient oil the wear surfaces should appear burnished.

If there is significant wear in the valve train, then you should remove the cam for inspection, and once the cam is out the rear bearing can probably be viewed with a borescope.

If it doesn't have a correct three hole bearing then the engine will probably have to come out to change it to the correct type and you'll probably need a new cam.

It's my understanding the the F-M CS165R does NOT have the rear groove as delivered, so you'll have to have once cut by a machine shop.

The advice in the How to Hot Rod Big Block Chevys comes from the Chevrolet Power Manual, however, it's my understanding that Chevrolet later rescinided the advice to solder and redrill the rear cam bearing. This has been discussed in the archives.

Also, for many years the GM service cam/pin assembly for all SHP big blocks including L-71 and LS-6 was 3863143, which has a groove, so the grooved cam was okay to use in '67-up blocks. Then few years ago GM "found" some 3904362 cam/pin assemblies, which is the same as the 3863143 except no rear groove. This was the OE cam used for L-71 and LS-6. So these long lost parts were available through service parts for a while until the supply was exhausted Joe L. relayed this information.

Duke

[Wayne M.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Yes, the distributors were part of the oiling "package" in 1965 and '66. Here's two examples of the partial annulus at the bottom of the BB distrib's used in the 1965-6 (and maybe even early '67 engines). Foreground is a "093" Corvette disr. the other is a '66 passenger "109".

Also, here's two drawings of the oiling passages in the early BB's ('65 and '6).

[John H.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Yes, the distributors were part of the oiling "package" in 1965 and '66.

However, the partial annulus wasn't necessary, and could cause a serious lifter gallery oiling problem if the distributor wasn't oriented properly, so they went to the full-annulus distributor housing in '67, which commonized the SB and BB distributors, and the full-annulus distributor housing became Service for ALL BB engines ('65-up). Just like the small-block, now the BB could have the distributor oriented in ANY position and not affect lifter gallery oiling.

[Ted K.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Thanks for the great info. I won't be able to get back to the motor for a couple of weeks but will let you know what I find out. Ted

[Larry B.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Before when you pulled the head for a stuck valve was there signs of oil or oil starvation. I very much doubt that it ran 3000-4000 miles without oil to the top end. Sixty seconds with a decent grade oil mite not have gotten there yet especially if you changed oil and filter.

[Domenic T.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Wayne or any one,
What about a 1972 454 block? I put a Isky 396 hydraulic cam 396271 in with 1969 427 crank, square port heads & Trw high dome pistons.
It has a gear drive instead of a chain (noisy) and after reading the posts here I looked thru the oil fill hole on the valve cover and only see enough oil to keep things lubed, I didn't see the squirt at the rocker but only a drop.
The lifters are Isky quiet power and seem to be quiet altho it's hard to say over the exhaust & timing gear set.
I've got 500 miles on it and oil pressure lite go's out instantly during start.
You mention the BB up to 1971 but what about a 1972 454 block with that 396 cam?

After not seeing the oil squirt when I looked thru the filler I thing I have something missmatched. It's in my driver Chevelle.

DOM

[Duke W.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

A 1972 big block should be the same as '67 - the annulus that passes oil to the lifter galleries is machined in the block, not in the rear cam journal as on pre-'67 blocks, and the rear cam bearing has one hole feed hole for the bearing. The early design uses a "three-hole" bearing. Oil entered the big hole from the block passage from the filter and entered the groove in the camshaft. The two smaller holes feed the lifter galleries. Due to the small bearing clearance that restricts oil that flows through the bearing, most of the oil entered the lifter galleries.

Prior TDB discussions indicated that GM rescinded its advice in the seventies-vintage power manuals to solder up and redrill the rear cam bearing oil feed hole if you were going to run a cam with a groove in the rear journal in a '67-up block. (You should be able to find this discussion in the archives.)

The conclusion from the above is that it's okay to run either a grooved or non-grooved rear journal cam in a '67-up block with an unmodified rear cam bearing. There was some argument over this as some felt that a groove in the rear journal on a '67-up block would create an internal oil leak at the rear bearing, which would restrict oil flow to the lifter galleries, but I don't think that's the case.

Flow to the bearing is primarily a function of bearing clearance, and somewhat on bearing size - both diameter and width. The fact that the groove effectively reduces bearing width might create slightly more oil flow through the rear main bearing, but this minor "leakage" would not likely cause a major reduction in oil flow to the lifter galleries. In fact, the rear cam bearing would probably not flow any more oil than in the first design, but the second design might be a little less.

Also backing up this conclusion is the fact that at least through my circa 1980 parts catalog, the service replacement cams for all '67-up blocks are all the part numbers for the earlier cams that have the rear journal groove.

When you check oil flow to the rocker boxes, make sure the engine is hot and you rev it up to the point where maximum oil pressure is achieved. Typical idle oil pressure is lower than maximum, so idle oil flow will be less.

Duke

[Domenic T.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Duke,
Thanks a bunch for that post, I did look thru the oil fill hole earlier and when my son reved it up the oil stream was sufficient. Your post is what I neeed to back up my decision to keep driving it.
This was a leftover idea I had when I built the engine as I had a good stock of parts and wanted to combine a few into someting I could later use. Now I am glad that I usd the high volume pump and ran the pressure higer than normal.

I usually check a combo out when I do something like this, but I built the engine years ago and didn't keep enough notes iti's log book.

DOM

[Philip C.]

Re: Oil Pressure on gauge but no oil at valve rockers 427

Recently had an intake valve stick and make contact with a piston bending the valve on 66 427/425 with 3-4000 miles since complete rebuild. Took it apart replaced valve, reassembled motor and before putting on valve covers and adding antifreeze started it up just to see how I was doing. Started right up, ran it for less than 60 seconds and saw no oil flowing from push rods onto rocker arms, dry. Oil pressure at gauge was 60 at idle and with additional rpm more than 80. What has happened. Why no oil on top end? Thanks

Ted let it run the oil will come up takes a little more time then you think. Phil 8063