Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


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Hi Rusty

I'm thinking what Kevin wants to know is what the trajectory of the oil stream looks like at actual operating volumes.
As he said, with enough flow the streams all hit at the same spot.
But as volume is reduced, one stream droops.

I do agree however that I would be looking to attain the same flow from all six nozzles.
And if the replaced nozzle looks and measures the same on the outside, I would think that should be attainable.

Just as an interesting aside...
I think the diameter of the outlet of the nozzles was changed at one point.
But it was actually made SMALLER with the change.
To show what I am referring to I'm attaching a picture of an early pan and nozzles (1937 on the right)
and a late pan and nozzles (1946 on the left).
Possibly this was done to "intensify" the streams?

Attached Images
Late Pan 2.jpg Early Pan 5.jpg
Last edited by Stovblt; 03/26/22 01:07 PM.

Ole S Olson
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It was done to get more cold oil to the rocker arms sooner to reduce valve noise during warm up.

On the low pressure 235 engines the rocker arm oiling was from oil taken from the rear cam bearing (which came from the rear main bearing) and piped to the head casting and (restricted) to the rocker arms. Dippper oil still from the low side of the distributor valve.
If the oil would have been taken from the high pressure side all the flow would go to the point of least resistance which would be the oil supply pipe for the dippers - which did not require high oil pressure.


Gene Schneider
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Hi Gene

That makes sense.

Most of my info sources are from the USA.
You point out that the low pressure 235's oiled the rocker arms from the rear camshaft bearing.
The blocks on Canadian 216's from about 1951 up were more akin to 235's in that they had the short push rod cover etc.
So did the late Canadian 216's also oil the rocker arms from the rear camshaft bearing?

BTW
My 1946 truck is American in origin. :-)

Last edited by Stovblt; 03/26/22 01:19 PM.

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Yes, because the parts list does not list the oil line that went through the block and other oiling parts used for that form of rock arm oiliing but does list the short oil line like the 235 used from rear cam bearing to the bottom center of the head like the 235 had.


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I could send you a list of the various parts used VS the parts not used but were for the US 216 engine. PM me or send me your email address.

PS
The 1939 way of rocker arm olling was a one year thing only.

Last edited by Chev Nut; 03/26/22 01:34 PM.

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Thanks!

Will do


PM sent

Last edited by Stovblt; 03/26/22 01:37 PM.

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Hi Ole,

I completely agree that the trajectory of the oil stream is critical. At higher speeds the dippers need to get oil from the steam from the nozzles. The action of the dippers in the troughs is so great due to speed that it almost leaves a channel or groove in the oil.

As always Gene is correct about the rocker arm oiling for the 235’s. That change to taking oil from the rear cam bearing was often a point of trouble. The oil had to pass around the rear rocker arm stand bolt. That small passage often would plug (sort of like the oil flow to the timing gears on a 216). Even with a bypass oil filter the lack of detergent oil allowed the sludge to form.


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You can find a fantastic old film showing actual high speed camera footage of the "pressure stream" system in action here:



Go directly to the 7:57 mark to see the main action.

This film is from 1937.
From 1940 up (I think) the oil pump capacity was increased and at some point the nozzle diameters were slightly reduced (as per my post above) so the advancing stream of oil in Kevin's 1947 would actually reach much further out by the time the dipper comes around and hits it.
The distance the stream reaches out between scoops should remain about the same regardless of RPM's because the volume changes in direct proportion to the RPM as no oil is being bypassed unless the pressure is above the 60 or more psi setting of the bypass in the pump itself. (which rarely happens, and never with hot oil)

Last edited by Stovblt; 03/26/22 01:54 PM.

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There was probably some sludge debris in the first nozzle I tried because I cleaned it reasonably well but didn’t visually check it. When I removed it I intentionally broke the solder joint to make certain solder wasn’t causing a restriction. Then I unsweated a second 1947 nozzle, thoroughly cleaned it, visually inspecting the bore in direct sunlight and then sweated it in place.

I compared both bores to a drill bit and they’re virtually the same size.
My theory is that they were manufactured in different decades possibly in different facilities or after retooling the same facility.
It very well be that the 1953 nozzles have a more favorable venturi effect and simply shoot further.

“Riding the film” is exactly what I needed to see! The dipper is intersecting the flow of oil only a short distance from the nozzle so it’s a negligible difference than the 1953 nozzles.
I’m at ease with the #4 nozzle as this is just farm equipment for the time being.

At this point I believe that the cylinder and wrist pin are more at risk of lack of lubrication on #4 than the rod with this header. Meanwhile I’ll be on the lookout for another header that matches itself.

Many thanks for all the information, now I’ve discovered collapsed exhaust valve springs so I’m going to see about swiping the ones from the 1953

Last edited by KevinDK; 03/26/22 03:39 PM.
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Spend a little bit of time researching the valve springs before you make that swap. One way that Chevy increased the power in these engines was to use a more aggressive cam. By that I mean it had more lift and duration. This required a stronger valve spring to ensure that the valve closed properly.

I'm not saying they will not interchange or that they are not the same valve spring. It's just that in the later 40's and early 50's there were lots of subtle changes in these engines. Hopefully Gene will jump in and offer the appropriate answer.


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The spring will be OK.
I am thinking more that the valve is sticking and the spring is OK.


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Okay scratch that.
Those rotating exhaust valve covers fooled me! Some of the exhaust valves are really loose.

I also checked the engine casting numbers, both the 1947 and the 1952 were manufactured in Flint and the 53 is a 52.

I also figured out for sure that my 1959 Viking Short bus is not a gas hog 261, it’s a 235.

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Originally Posted by Chev Nut
The spring will be OK.
I am thinking more that the valve is sticking and the spring is OK.
Some were initially, I bent a push rod at first.
They are all moving nicely now.

What I discovered was all the exhaust valves were loose especially #1 by about 3/16”. I knew about the revolving plates but wrongly assumed that they were held in place by keeper and the slack was between it and the spring. Hence my confusion.
Originally I had compression on only number 2.

Once I crawled under the engine and was able to assure TDC I discovered 5 extremely tight valves. Someone must have assumed that they were hydraulic valves because they were ridiculously too tight.
I was going to weld up a spark plug base to an air chuck but someone suggested using the adapter from a compression tester and after removing the schraeder check valve it worked great!

Now when I apply air pressure on a cylinder past TDC the air pushes it to the bottom of its stroke.

The #6 dipper is swiss cheesed so while I am replacing it I will inspect the journal and check the tolerance with plasti-gauge. All of the dippers are squared off at the very bottom and seem to have too much clearance. Today I will complete the measuring gauge and check #6 once it’s replaced.

I’m excited to replace the pan and do another compression test!

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Thanks for the update. Sounds like you are making progress. It is hard to imagine how something like those valve adjustments got done. Things like have taught me to never be surprised at what I find on an old vehicle.

I agree that you need to gauge to confirm the dipper height. If I remember correctly the dippers on my car are fairly square. The idea is that you want them to just scoop the surface of the oil in the troughs. If they go too deep the bottom end of the rod displaces all of the oil out of the through. Plus it is adds drag on the rod throws of the crank.

If you look calculate the dimensional differences of the gauge you should find that the dipper only goes about 1/4” below the top edges of the trough.


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Originally Posted by Rusty 37 Master
Thanks for the update. Sounds like you are making progress. It is hard to imagine how something like those valve adjustments got done. Things like have taught me to never be surprised at what I find on an old vehicle.

I agree that you need to gauge to confirm the dipper height. If I remember correctly the dippers on my car are fairly square. The idea is that you want them to just scoop the surface of the oil in the troughs. If they go too deep the bottom end of the rod displaces all of the oil out of the through. Plus it is adds drag on the rod throws of the crank.

If you look calculate the dimensional differences of the gauge you should find that the dipper only goes about 1/4” below the top edges of the trough.





Thanks, I don’t know why I thought they were rounded, maybe that’s Hudson.
According to the 3-23/32” tool these are a little high by like 3/32” which is good enough for now. I appreciate the help! I need to apply it to my 1936 town coach before I take it out on the road.

The rod cap wouldn’t budge when I changed out the dipper so I didn’t get a look at the journal. I just prayed and torqued it to 45, it took 65ft # to break it loose. I was able to remove the cap on the 1952 and it looked nice. I need to soak the rings and and keep the water out of it. It seems to have been rebuilt.

The valves weren’t maladjusted after all, four lifters were stuck, especially #1& #4. They were what was creating the current knocking sounds. Hopefully it was the sound that caused the owner to park it in 1958.Then again it could still be a piston rod and the valves didn’t stick until a really wet winter in 1960.

Now all the lifters are spinning nicely and it’s making 75-100# compression. I’m going to pickle the rings with some 9% vinegar while I go deal with other first world problems. In a few days I’ll let it soak in some of my home brew penetrating oil hopefully by the time I apply air/fuel +spark they will loosen up and the compression will level out.

My next concern is I’m still having to lubricate the valve train.
I disconnected the feed tube and forced air through both directions which sprayed me with oil from the rockers and I could hear bubbling in the sump in the other direction so at least I know it’s not blocked.
I tried to prime it through that tube but it’s just too small.

Maybe it’s rejecting the oil I put in it. It’s out of a 1970 Ford F600!
Not to worry, when the rings are finished soaking it’s getting a proper oil change before I try to fire it up.

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