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Oil passages to main bearings - different diameters


Bryan

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4 hours ago, Loren said:

 

When you look at a HyDrive engine there is a relief valve on the oil pump in addition to the one in the block.

It makes you wonder why they put that there.

Could it be that the Torque Converter generated its own pressure?

Aside from people forgetting to drain the Torque Converter every engine oil change, I wonder what the engine longevity is vs a standard shift.

HyDrive has always fascinated me being the ultimate FluidDrive. If it added to the life of the engine that would be another reason to find one.

 

(one of my modern cars needs to have a transmission oil change every 70,000 miles. The car lets you know its time when the transmission slips going up a hill in high gear. After I had the dealer do the service -once, I only got 55,000 miles and it was slipping again. I talk to a number of friends in the trade and they said, "Nobody drains the Torque Converter". Needless to say I now do that service myself)

I think this is an interesting subject. One historical thing I noted was that in 1960 the LAPD required that its replacement fleet of cars had to "share oil" with the engine. These were 318 blocks or 383 blocks I think. The only trans that could meet the spec was the Powerflite not the Torqueflite. One thing I have never found out was did that spec mean the engine and trans had oil circulating between then or the LAPD just wanted to stock only one oil...

 

James

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2 hours ago, James_Douglas said:

I think this is an interesting subject. One historical thing I noted was that in 1960 the LAPD required that its replacement fleet of cars had to "share oil" with the engine. These were 318 blocks or 383 blocks I think. The only trans that could meet the spec was the Powerflite not the Torqueflite. One thing I have never found out was did that spec mean the engine and trans had oil circulating between then or the LAPD just wanted to stock only one oil...

 

James

If they added branches or more circuits to the oil system they would have to increase pressure and pipe size before the extra part for the trans/torque converter. Still trying to understand how they could branch  .315 & .25 pipes off of a .33 main line and still get enough oil flow to the mains.   I know the main journal holes and cam bearing holes affect this, but also the camshaft & main journal surfaces covering the holes, plus the passages to the rods and their surfaces.

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I think the currently available cam bearings are drilled to fit the old larger cam oiling holes and the newer, smaller holes as well.  Hence the choices.  Be interesting to see what an NOS set has, pre cam oil hole changes.

 

Assuming my cam oil hole change recollection is accurate, lol. 

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1 hour ago, Sniper said:

I think the currently available cam bearings are drilled to fit the old larger cam oiling holes and the newer, smaller holes as well.  Hence the choices.  Be interesting to see what an NOS set has, pre cam oil hole changes.

 

Assuming my cam oil hole change recollection is accurate, lol. 

Only problem is the rear cam surface doesn't really have a bearing.  Sam was mentioning boring and putting an insert bearing there.  Wonder if one could tap & thread the hole (if they could have enough working space) and put a small restrictor there.

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50 minutes ago, Sniper said:

Well, a drill bit drilled the hole, so there has to be access from outside the block, but who knows if a tap is long enough.

I didn't explain it well. Meant threading the .25 cam hole from inside the journal opening (the opening the rear of the cam fits into).

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I have often thought about that rear bearing. If you wanted to restrict it, you could push in a thick roll pin from the cam side. Take a careful measurement of the bearing surface, check the manual for clearance, measure the cam and have it hard chrome plate to bring the clearance to the low end. Cast iron to cast iron bearing surfaces are acceptable but cast iron to hard chrome is better. You don’t have to get too fussy about that bearing as number 6 rod doesn’t share oil with another rod. A good automotive machine shop can align bore the block for an insert bearing as well.

 

In a conversation I had with John Kilgore (who builds racing automatic transmissions) he stated that he saw no reason why you couldn’t use motor oil in an automatic. ATF is rather thin which has proven to lower temperatures. However, the latest specs for motor oil is getting rather thin as well. I don’t believe he was talking about sharing the oil like the HyDrive (or the original Austin/Morris MINI for that matter) The whole function of the HyDrive torque converter sharing the engine oil was to cool the oil. 11 quarts of oil can dissipate a lot of heat. The thing is a torque converter can generate an amazing amount very quickly. The Baker Grade on the way to Las Vegas is evidence of that with scorch marks every 100 feet from RVs burning to the ground from overheated transmissions. ATF will burst into flame at 425 degrees.

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Messed up sciatic nerve in my left leg Saturday using a push mower around a steep small pond. Sat evening Sunday were  painful days.  Sitting here doing calculations on oil gallery sizes.

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  • 2 weeks later...

There used to be a company that sold kits to put in a restriction in the rear oil feed of these blocks to make up for the wear at the rear cam to block interface. When that rear "bearing" wears too much oil pressure can be lost. Hence the kit.

 

I like the idea of pressing in a bushing to bring it back to the low end of the spec. Loren, what about an oilite bushing? Good cam cores are more important, I would rather change that bushing on a rebuild...

 

James

Edited by James_Douglas
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7 minutes ago, James_Douglas said:

There used to be a company that sold kits to put in a restriction in the rear oil feed of these blocks to make up for the wear at the rear cam to block interface. When that rear "bearing" wears too much oil pressure can be lost. Hence the kit.

 

I like the idea of pressing in a bushing to bring it back to the low end of the spec. Loren, what about an oilite bushing? Good cam cores are more important, I would rather change that bushing on a rebuild...

 

James

Saw those, but the rod connecting the ends would use up some area. Like her idea of putting a restrictor in the cam oiling hole (only on the rear). Just need to make sure it stays in, and is not too small.  Larger than needed is a good idea if a crust layer builds up like I found in mine.  Need to be careful => on this block the cam holes were about .25".  On the old block they were large, all .33".

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Since I'm still recovering from sciatic nerve problems in my leg and having the small skin cancer taken off my head, thought I'd take a few pics of the galleries with my recently found (6 yr old) borescope.  Dang, after the machine shop block cleaning, me cleaning and 2nd pressure wash, at the microscopic level still looks like crap.   Picture Order: Main gallery, side gallery, relief valve (notice seat), better lighted side g,  side g.

Main oil gallery USB Cam ex light.jpg

Oil side galley w USB cam 23 June.jpg

Relief valve socket w USB cam.jpg

Side oil gallery lighted.jpg

Side oil gallery w USB cam lighted 23 Jun.jpg

Edited by Bryan
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  • 4 weeks later...
On 6/5/2022 at 10:50 AM, James_Douglas said:

The rear cam "bearing" being the block itself is known to wear. Back in the day there were restriction devices that were sold so that oil pressure would not drop off due to that wear. They come up on ebay now and then.

 

 

Found that paper in another post. Read through it again and voila!  They were drilling the oil passages different sizes based on year.   Read the excerpt from the NOS restrictor paper.

Oil passage excerpt.jpg

Oil passage.png

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  • 1 month later...

Well today I went ahead and drilled the side oil galleries out to the back of the T junction going to the main bearings.   Used a 21/64 drill on the front and rear galleries.  Was going to do the two middle galleries with a smaller drill bit, but when I drilled, the holes still had a ledge about 1/2 way in. So I used a 5/16" drill. Thank God I didn't break thru anywhere.

 

Found on the front and rear galleries you have to use a 6" long bit, not the 4.5". Otherwise the drill chuck hits the generator pad flanges on the front,  and some raised area at the rear.

 

Used electrical tape to mark how deep to go, and also to protect the threads on the oil fitting holes. 

Forgot to mention, I did not drill the vertical # 2 & 3 mains oil passages out, which are smalller than the front and rear. On the side galleries the ledge is so deep, you have enough bit in the hole to keep it straight. Didn't want to risk getting the bit out of line.

Drill bit bore out.jpg

Drill bit borelonger .jpg

Edited by Bryan
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The problem I would worry about is seepage.

 

On the 1949 Desoto, go read the long threads I had on this, we had oil seeping from the gallery up through the floor of the water jacket. It was slow, took a couple of hundred miles. That oil would then float to the top of the head, act like a blanket, cause local hot spots and crack the head.

 

Turns out that if you look at the photo I have attached that the distance from the gallery to the floor of the water jacket is very close. Any porosity in the block at that point from the original casting or rust over time and it can be a problem as I found out. It required swamping in a new engine for a new engine.

 

I would plan on doing a full pressure test at 100 PSI of the oil distribution system to make sure that is not going to be a problem. Yes, this is a PITA as you have to press in a set of cam bearing blocking the holes then removing them. Not to mention all the other things that you have to plug. 

 

A friend who is big into drag racing suggested I get some of the stuff they pour into drag blocks to stiffen them up. A 1/4 mile is not long enough to cause a heat issue and they often fill the water jackets 1/2 up to stiffen them. He suggested after I clean my "bad" new engine that I pout like a 1/4 inch in to the floor of the block to seal any seep holes. He take is it could ave this rebuild engine. A thought.

 

James

 

 

galleries.JPG

Edited by James_Douglas
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