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MrMack,Ona picture it may look the same but the screen is of a different size and the mounting of the screen is different.Check my last post'''''I did an edit.On the 37-39 the pick-up is direct and not bolted to main brg.cap.

Gene, aren't all of the Chevrolet oil pumps from 28 to 62 pulled by the distributor with a male distributor and a female pump shaft? The gear pump shaft was threaded and an extension shaft screwed on, and probably locked. can't see why or how the pump can capture the distributor shaft, don't it just mate tang to slot? Why would the didtributor shaft jump up and down?
...and it looks like the screen housing was ground down to fit the 28 pan.

In the 1929-36 oil pumps the 1936 is the only one that the tang that connects the dist. shaft to the oil pump (male end) is located on the end of the distributor.Also the oil pump shaft is larger,9/16"instead of 1/2 & set screw is 3/32" larger.The 1936 distributor and oil pump fit only a 1936 due to these changes.When Chevrolet made the gear type oil pumps to up date the 29-36 vane pumps there were five variations,604506 fit 29,604507 fit 30-32 & 33 & 34
Std.,604508 fit 33-34 except Std.,604509 fit 35 and 604510 fit 36.These were complete change over kits with all parts included to install..........The end of the dist. slips into the oil pump---no connectors-----on the 216 set up the slot in the oilpump engauges with the the pin thru the dist. gear.

Q&A

Chev Nut,

Your comments of Nov 15, 2002 06:28 are 100% correct and on target. More response later.

ChevyGuru,

Didn’t mean to get so uptight, but wanted the thread to stay as reasonably close to the original subject as possible.

MrMack,

My idea of replacing the oil pump with a gear pump is not at all original even if a vane pump were available. This has been done for years. However, I think your comment is a bit strong about the idea of maintaining originality. Unfortunately our history file on this site doesn’t go back far enough to include the farce I wrote on replacing components on a ”˜28 with S-10 items. Short story was that EVERY item was replaced except the Griffin Radiator Cap because I wanted to at least keep it ORIGINAL.

Chev Nut,

Your posts of Nov 18, 2002, 19:16 and Nov 19, 2002, 16:25. All of the data you have posted is extremely informative. That is an excellent summary of the original oil pumps and the updating of all the early vane pumps by a gear pump. Obviously Chevrolet felt the gear type pump was superior to the original vane type. The 64-dollar question: Why did I choose a ’36 pump? Because that one was in stock. Any gear pump of the period would have been acceptable. In my application, either the entire shaft could have been replaced or since I did not have a piece of round stock of the proper size on hand it was easier to cut, thread and extend.

MrMack,

Your posts of Nov 18, 2002, 19:51 and Nov 18, 2002, 21:09. All of these oil pumps can be easily identified by the part number, which is on the shaft and repeated on the pump cover. If you go back to the second picture in the post on the oil pump you will notice that there is an indention on the slot to ”˜capture’ the distributor. The only thing that holds the distributor in the engine is a single screw which is spring loaded. With a slot and a tang mating the distributor will be mobile as the cam gear is forcing the distributor in two directions simultaneously. Therefore the slit is modified to ”˜hold’ the distributor shaft. Other modifications were made to the installation to provide for ”˜fit’. And finally, the model number that I used was 604510.

Okay students, I promise that the next class will be on the installation of the crank. Class dismissed.

Ok, that splains my question satisfactorially, and I did remember your comment about the S-10, I have no problem useing a modifed pump in order to complete an engine and get the car onto the road, I just wouldn't see why it would be done to increase the oil pressure. but to do it because an original pump is not available at a reasonable price sounds like a good idea, otherwise someone that hordes a few original items can hold you up ,pricewise, and it happens too often, IMHO

Class is in session. Please take your seats.

We have just a few more loose ends to tie up before we “lay that crank”. While the crank is out of the block is a good time to make the final installation of the oil distributor assembly with pipes.



This is one of the attachment points in the block to secure two of the pipes. Notice that this is a through hole in the block. Any time you have a hole that goes through the block you have an excellent chance for an oil leak.

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On the left are the two brackets that secure the pipes on each end. Notice there is a bolt, a lock washer, and a copper sealing washer. In the center of the picture is the bracket that holds the spark rod as it goes through the engine block between #2 and #3 cylinders. To the right is another copper sealing washer and finally the fittings that go through the block to attach the distributor.

[IMG]
One of the items we all have sitting on the shelf in the shop is a can of gas tank sealer. This is the old formula that was yellow and was named “yellow snot”. It is no longer used to seal the tanks as it was not resistant to alcohol and has been replaced by the ”˜white snot’. The company that never did get their engine colors correct, but that’s another story made this stuff. The reason we didn’t throw away the yellow stuff is that it makes an excellent sealer. By using this stuff it is safe to reuse the copper seal. The seal has been dipped into the sealer and is now ready to be assembled.



This is the return fitting from the oil filter and also has a copper washer for sealing purposes. It has also been dipped in the gas tank sealer and is ready for assembly.



This is one side of the oil distributor and shows two of the pipes. Notice the special bracket with the through bolt and the square nut. This bolt, copper washer and nut were also dipped in the sealer before assembly. The other two pipes are held on the other side of the engine by the same type bracket, bolt, washer, and nut. The fitting you see in the picture is for the connection to the oil pump and is the feed line.

In preparation to lay the crank it is still squeaky clean from the hot tank and the polishing procedure. The ½ shells have been laid in the block in their assigned spots and are also clean and dry. Very carefully the crank is laid into position. When the engine was disassembled note was made of any and all shims used in each main bearing and their location. As the engine obviously has seen many hours of operation, shims are removed arbitrarily for the first test fitting. One method of checking the oil clearance in a bearing is the use of PLASTIGAGE. This is a wax like material that is shaped in a string and has an exact size. This string is placed between the bearing and the crank, the other ½ of the bearing is installed, the bolts are torqued to specifications and then the caps are removed and the displacement of the plastigage is measured with a scale provided. This tells how much clearance exists. Plastigage is available in three sizes. The green package is for measuring clearances from .001 to .003, the red is used for .002 to .006 and the blue is used for .004 to .009.



This is the rear main. I have laid the plastigage diagonally across the crank in order to measure some width along with the length. Actually, the crank should be measured at two different locations. With the crank at top dead center and at a 90 degree location. This is to check for egg shaped crank. Most wear on the crank would be at the top or bottom of the piston travel. All shims were removed from the rear main. It appears that my oil clearance is about .002. The repair manual does not specify a clearance for oil, however it does caution against having them too tight. This would cause heat that could easily melt the thin coat of babbit. I am satisfied with the .002, but realize the next time the engine is repaired it will be necessary for new mains as there are no more shims to remove.



This is the center main. The reading here is also about .002+ and all shims have been removed here also. The center main serves as the thrust bearing in the 4-cylinder motor. When you push in on the clutch you are shoving the crank up against one side of the center main. The clearance for the center main thrust is .004 to .006. This clearance can be measured with a dial gage or by use of feeler gages.



This is the front main. The reading here is also about .002+. This bearing still has a number of shims left on each side. However, because the center and rear are out of shims the next disassembly will call for a complete rebuild.

Now that all the bearings have been measured we can get ready to ”˜button up’ the crank. All traces of the plastigage must be removed from the crank and bearing shells. The crank should be removed for the final time. Each bearing ½ must be liberally oiled with assembly lubrication. The crank should also get a good coat at all the bearing surfaces. Starting with the center main each bearing cap should be torqued to specifications. After tightening each bearing the crank should be turned to insure it still turns easily. The assembly lubrication makes the crank harder to turn than when it was dry. When all bolts are tight the locking tabs should be engaged on each cap bolt.

Now that we have ”˜laid the crank’ we will work on the front of the engine next session. Class dismissed.

Student with hand waving in back of the room.
Hey Teach, I have a few questions.

Do you recommend rotating the shaft on dry bearings? Is it only for shafts that have been polished and checked for straightness? How is straightness checked?

Was the thrust 0.004-0.006" as measured in places around the shaft and bearing? Of were you just giving us the specification range?

Student now standing on desk to get better view of engine and as a result of excitement.

If the thrust is in specifications aren't you really lucky as most of the engines that I have measured have over specification thrust when there are still shims in the main bearings. I think it may be from people riding the clutch or holding the clutch pedal in while stopped for long periods.

Did you do any checks for the intregrety of the babbitt? If so what were they? If not how do you tell if the babbitt is not getting oxidized and brittle? If brittle then it will come loose from the shell and all hell will break loose (pun intended).

Ok, I will let other students have a chance. Sorry but I get excited when we get to the putting back together stage.

So, you were able to tell that the thrust wear was at the forward side of the bearing flange? is there a thrust wear shim for the bearing flange, or must it be replaced when the thrust wear exceeds specs? I suppose there is also other damage internally to an engine from riding the clutch, and not just to the clutch itself, very interesting! Charlie Chip Chan.....

The Chevy 4 was a common engine to modify for racing.What did they do for lubrication???With the mains depending on oil thrown up by the rods it must have taken forever for the mains to recieve oil ...especially in cold weather.It would take a bit of plumbing but piping oil up to the mains as in '29-'31 would sure help.At 50 MPH 3.82 gears and tall tires the engine must be turning over at about 2100 RPM which must be the limit for a stock engine.

ChevyChip,

Q:

Student with hand waving in back of the room.
Hey Teach, I have a few questions.

Do you recommend rotating the shaft on dry bearings? Is it only for shafts that have been polished and checked for straightness? How is straightness checked?

A: The reason I wanted the crank and bearings dry is to get a more accurate measurement. With a polished crank and seated bearings the chance for damage is small. When the crank was in the lathe for polishing the straightness was checked and found to be satisfactory. The limit is within .002 of perfect.

Q:

Was the thrust 0.004-0.006" as measured in places around the shaft and bearing? Of were you just giving us the specification range?

A: The figures given were the specifications. Actual measurements were pass on a .006 feeler gage and lock on a .007. On the outside of specifications but still acceptable. If the engine has a detectable knock this figure could enter into the diagnosis.

Comment:

Student now standing on desk to get better view of engine and as a result of excitement.

Response: Please get off the top of the desk. If you were to fall your parents would hold me responsible.

Q:
If the thrust is in specifications aren't you really lucky as most of the engines that I have measured have over specification thrust when there are still shims in the main bearings. I think it may be from people riding the clutch or holding the clutch pedal in while stopped for long periods.

A: As I constantly recommend against prolonged idle, this is another no no. If it is apparent that the clutch must be depressed for a sustained period the transmission should be shifted into neutral and the clutch released. The center thrust bearing is a more durable material than the bearing, however it is commonly worn badly on most disassemblies.

Q:

Did you do any checks for the integrity of the babbitt? If so what were they? If not how do you tell if the babbitt is not getting oxidized and brittle? If brittle then it will come loose from the shell and all hell will break loose (pun intended).

A; Each of the 6 ½ bearings were removed from their seats and shells and inspected. The mating edges were filed where the babbit had drifted to the mating edges. None of the bearings showed any signs of cracking or gouges. Some discoloring was observed, but in the end all bearings were found to be serviceable.

Comment:

Ok, I will let other students have a chance. Sorry but I get excited when we get to the putting back together stage.

Response: The most exciting part is the first firing of the engine after installation.

MrMack,

The wear on the thrust bearing is on the back side of the bearing. The crank is thrust forward against the back side of the bearing. There are no shims associated with the thrust bearing and if out of specifications must be replaced.

Chev Nut,

I do not agree that it takes a long time to splash oil on the main bearings. Unless the engine has been idle for a considerable time period there would still be residual oil in each of the reservoirs. As soon as the engine was started the bearings would receive some direct splash and the reservoirs would fill quickly. In modifying the 4-cylinder engine for race use the most critical lubrication issue would be an oil pump that had sufficient capacity to keep the 4 troughs full at all times. While on the National Pre-29 Meet it is not unusual to find most cars capable of sustained speeds at or in excess of 40 MPH. I estimate that I was doing in excess of 50 MPH in my ”˜25 when I blew the timing gear in Durango, CO.

OK, I see what you mean by the wear on the rear flange by the crank being thrust FORWARD, I was 180* off I reckon, that was what I was wanting to know, And I agree with Chip that the splash and dip system should provide instant lubrication to the lower engine parts, except maybe the timeing gears. I believe the main addition to a higher volume and pressure gear pump , for racing engines, the main modification was a large volume pan to give a large volume of engine oil for additional cooling and as a hedge against oil consumption

The main bearing thrust problem is not only on stick shift cars.With an aotomatic trans. this can be a problem too.Under constant heavy loads,most common in trucks,the torque converter can exert pressure on the thrust bearing also......Also have seen it mentioned in older manuals that if there is still too much end play in the crankshaft due to wear the new bearing can be built-up with solder to take up clearence..........Also glad to hear MrMack admit he is a little off :confused: like the rest of us old car nuts.

Gotta quit making my posts after midnight.

In addition to replacing the center main/thrust bearing, the crank can be welded and turned to fit the current bearing. That would have been an option in my case. This solution can generate more work however. After the welding and turning the crank, it will be necessary to check the straightness again as the heat from the welding could affect it.

Attention students, class is in session again.

This session continues the study of the oil flow. The picture is of the front of the engine. This is before the gear cover plate is installed. You can see the front end of the crank in the lower right side of the picture. The large hole in the upper left is the front cam bearing.



If you look directly above the crank you will observe two holes close together. These holes go through to the inside of the block. These two holes are the main entry for oil into this cavity. The single hole marked with chalk in the lower left is the return hole back to the pan/sump. In the extreme upper right of the picture is an entrance hole from the outside of the block. This hole is where the end of the draft tube from the carburetor is attached. More on this tube later, but this is where the burned gasses are scavenged and directed back into the intake through the carburetor. In the lower left corner marked by chalk is the location of one motor mount bolt. This is a through bolt. That is, it is threaded into this cavity. If you have an oil leak at the front of the engine that is driving you crazy, remove this bolt, coat with the gas tank sealer (yellow snot) and replace. Notice that at about 4:30 on the cam bearing is an oil grove. Splash oil from inside the engine and from the reservoir above the cam bearing can traverse this grove and will end up past the gear cover plate to lubricate the cam gears. Other than the small amount of oil that gets by the front main bearing this is the only means of lubrication for the cam gears.

Class dismissed. More study on the system to lubricate the cam bearings and other locations to leak oil in the next session.

Since tomorrow is Turkey Day the class will be short so you can get ready.

This picture shows the block upside down and is the passenger’s side.



The locations marked 1, 2, & 3 in chalk are soft plug locations. However, water is not behind them. These are the access holes that are drilled from the outside through the cam bearings and all the way into the reservoirs for each cam bearing. It is necessary to remove these soft plugs before the block is hot tanked. In the cleaning process a wire brush can be inserted all the way into the reservoirs for a good thorough cleaning.

When we have finished assembling the block the new soft plugs will be installed and as usual sealed with a liberal application of “yellow snot“.

Note the two holes between #1 and #2 on the photo. They are indicated by the two arrows in chalk. These are through holes used to mount the oil filter and coil mounting bracket. So, since they are through holes, what do we do with them students? Correct, a liberal coating of the “yellow snot” on the threads of the two mounting screws.

Directly to the left of the #2 is the setscrew and locking nut for mounting the oil pump.

Class dismissed. Don’t overeat on the turkey and be back in class for the next project, the timing gears and cam installation.

Students if you are not too full of turkey and vittles we will continue with the study of the 1928 4-cylinder engine.

The next step in the assembly is the camshaft.



Notice the plate behind the cam gear with two holes in it. That is the camshaft thrust plate. This plate is installed on the cam first followed by the cam gear. The cam gear is pressed on to a clearance of free to .001.

Initially when the cam was removed and before cleanup it was decided to reuse the cam as removed. After cleaning it up it was decided that although not absolutely necessary it would be best to have it reground.



This is what you expect to see a cam lobe look like. A nice clearly defined point. In most 4-cylinder engines all the lobes look like this one. However, in the 1928 engine this lobe is only used for the exhaust valves.



This is the shape of the intake valve lobes. Notice that this lobe is almost completely flat on the top. This configuration holds the intake valve open longer allowing a greater charge of the air fuel mixture.



The lifters were changed on the 1928 engine to the flat bottom type, which are the preferred type, and are used in later Chevrolet engines. The lifter on the right is the ’28 lifter and the one on the left was used on most of the early engines. The early lifter had a slightly rounded end, and as a result wore a saddle in the lobes of the early camshafts, because of this configuration. Much less wear, and therefore extended life, is experienced on the ”˜28 camshaft.



After a good coating of both the camshaft and the bearing surfaces in the block with assembly lubrication, the cam is inserted into the block. This application uses a metal crank gear and a fiber cam gear.

In 1927 Chevrolet reversed the normal composition of the crank and cam gears in the engines. For ’27 the cam gear was metal and the crank gear was fiber. Another confusing issue was the use of a different number of teeth in each gear. For 1927 ONLY, the tooth count was 46 cam and 23 crank. All other gear sets were 52 cam and 26 crank. The ’27 gear sets may be used in the ’26 and ’28 engines IF USED AS A SET ONLY.


Here is where we start getting in trouble. The mating mark on the cam gear is on a TOOTH. The mating mark on the crank gear of course is on the valley or between two teeth. IF YOU HAVE THE AA-AB CHEVROLET REPAIR MANUAL EFFECTIVE FEBRUARY 1ST, 1928, GO IMMEDIATELY TO PAGE 42 AND CORRECT FIGURE 42 FOR THE SERIES AB. The assembly marks are backward.

To make matters worse, and has been pointed out in this Chevy Chatter before, many aftermarket fiber cam gears are mismarked. If you have an OEM gear to copy the mark from, use it.



If you don’t have an OEM gear you can construct a line through the center of the cam gear and in line with the keyway. Then count 15 teeth counterclockwise to locate the mating mark on the cam gear.

Enough for this lesson as I can see several of you nodding off as a result of overeating. Next class will cover the widely held misconception of the relationship between the assembly marks on the cam and crank gear and TDC (top dead center).

(Loud banging on the desk in an attempt to get the attention of the students).

In our dialog on cam gears we failed to mention the difference in width of the gears. The F, G, 490, Superior and U all used a cam gear that was 5/8 inches thick. The C (”˜27) and N (”˜28) used a 13/16-inch thick gear. Although the later (13/16) gear could be used on the earlier models in most cases there was not enough room under the cam gear cover for clearance. Extra gaskets and physically deforming the cam cover has been attempted in order to make it work. Some have attempted to shave off a portion of the gear. I can attest to the results of this scheme. I had shaved a gear that I used in my ”˜25 and experienced a complete destruction of the gear in Durango, CO. I believe that the removal of the hardened surface of the gear weakened it sufficiently that it failed.

For your viewing pleasure.



1927 Capital 13/16 steel cam gear part number 346875. This gear is for use with the fiber crank gear part number 346874.



This is a 13/16 fiber gear part number 348590 and is used with the steel crank gear part number 348591.



This is an after market fiber 13/16 gear for use with the steel crank gear in either the ”˜27 or ”˜28 if used with the steel gear. This gear was NOT mismarked. It wasn’t marked at all. The mark you see added was based on a transfer from an OEM gear.



Study this picture closely. You will see that the marks on the cam and crank gear are ”˜mated’. Now look at the location of the crankshaft. Notice that the lobes are not vertical. The point I am making is that this is not the TDC (top dead center) that would be used for the installation and registration of the distributor. For years it has been difficult to convince people that the mating marks are FOR ASSEMBLY ONLY and have absolutely no relation to the TIMING of the engine. It is easy to see from the picture that if you looked through the hole in the flywheel cover you would NOT see the timing mark. After the timing gear cover is installed, so you can’t see the marks, is the time to place #1 cylinder at TDC, with both valves closed, and then install and time the distributor.

Class dismissed. Please place your chairs under the table, and don’t forget to take your books with you. And would someone please erase the blackboard and dust the erasers? Thanks.

Thank you so much for the very informative lesson, Sir, however I would ask that you not bang on the desk quite so loud next class. You caused me to awaken so suddenly, I fell out of my chair and struck my head on JYD's steel toed boot. This in turn startled him causeing him to bite my right forearm. After class I had to go the hospital for rabies testing and because we were not able to catch the mangy curr, (he was chasing Elvira and hasn't been seen since). I forced to spend about eight hours in the hospital to clean the wounds he inflicted and to get about 156 stitches. I have also had to endure a series of immunizations. (ya just never know where those Junkyard Dogs have been.)

Now, does the assembly procedure you just described apply to the Six as well?

Dan.

Dan,
In a few words, basically yes!

Dan, It seems that the "Six' that you need working is a .45 Colt Sixshooter! from all the problems you have with those slightly "Green Broke" Timber wolves going around acting like Junkyard dawgs!

Great post Dan! :p :p

Ya, I thought so too!

Although I didn't see you mention that you installed a new timing gear I assume that you did (at least the fiber) as I feel that this is weak link in the chain.

Very fascinating, this fiber gear on crank, steel on cam or steel on crank and fiber on cam. I wonder why they insisted on using fiber at all ? What would be wrong with steel to steel ? I have noticed that the later truck sixes used steel and aluminum, again why no steel to steel ?

I agree with Chev Nut, fiber is the weak link. I had one go on a 235 one time and never forgot that happening!

It's a noise factor.