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Finding TDC and Installing KA24E Oil Pump


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In the middle of my L20b cleanup/upgrade before dropping the engine into the 510 and of course I run into areas I haven't had experience with. For example, I already had my Mallory distributor out and was cleaning it up and decided that it would be a good idea to also upgrade the stock oil pump to the higher volume KA24E pump. Had seen another post on here where someone recommend using pliers to hold the oil pump shaft in place up at the distributor and then drop the oil pump and install the new one. Working great until my wife called me and I stepped out of the garage for 30 seconds and came back to the pliers on the ground and shaft there as well. In reading the How to Rebuild Nissan/Datsun book, it instructs that you get the engine to TDC and then install the shaft/pump. Well since my timing marker was removed for painting and this idiot painted over the TDC mark on the crank pulley I had no idea where TDC was (I used to know this stuff when I was 17!). Searching on google/ratsun I followed the following steps:

  1. Pulled spark plug #1 to view the piston
  2. Pulled valve cover to see camshaft
  3. Rotated crank until piston was at the top of the cycle
  4. Ensured that the intake and exhaust lobes were pointing at 10 and 2
  5. Looked through the cylinder head at intake and exhaust valves and both looked to be closed.

My questions on finding TDC are:

  • At the top of the stroke I could still move the crank forward or backwards slightly the piston really didn't move up or down. Normal?
  • Am I missing anything else that I should check to make sure I'm at TDC (some pics below)

Assuming I was at TDC I did a dry install of the new oil pump. Can someone look at the tang position and let me know if it looks ok? Much appreciated as always!

 

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If the timing mark on the pulley has been painted, UNPAINT it, you should find a notch, mark it w.white out or a paint pen.

 

To verify the cam timing, look thru the big holes in the cam gear and look at the position of the relationship of the notch in the gear and the scribe mark on the thrust plate, the gear notch should be over lapped to the right of the make.  As mentioned, your tang orientation is spot-on.

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Distribuitor alignment looks correct. As Doctor510 said unpaint it or not as the notches should be visable. If so simply paint white the TDC notch then use a dial back timing light. When I built my last L engine, an LZ2.2 I physically checked the tdc mark and found it off by 2 degs,,,,2 degs. So I painted the factory marks black and filed a new tdc notch and painted it white. When I rebuild my SR I'll be checking tdc marking but I'm sure it'll be spot on.

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It is certainly close enough for instaling the distributor, more than enough.

 

If you need a good TDC for ignition timing it's only close but at near TDC the piston moves very little but the crank moves a lot so it could be way out. Only way to know for sure is pull the plugs so compression isn't a problem. Get a bright light (LED) and see if you can see the piston top. Maybe a pencil or something touching it? Bump it back and forth through TDC and watch for movement.

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Man I really have to take the time and understand the timing of these cars. I know it's so simple but just haven't had to deal with non-ECU cars for so long now. Well thanks to you guys I have my oil pump installed (see build thread), found the notch on the crank pulley (now marked in white) and am 99% sure I'm at 100% TDC. 

 

Loosely installed the distributor mount which I never detached from the distributor. Remember nothing was supposed to move until the shaft came out and I had to crank the motor around to TDC. Since I know the motor was running perfect before as this I wanted to just ensure it was at the same timing before it was removed by the previous owner and picked up by me. 

 

Can you guys take a look and see it anything is off? Thought that at TDC the distributor rotor should be pointing at #1 but I am pretty sure it pointing at #4. I can take more pics if it is helpful. 

 

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The mark is at TDC right now on the crank and based on everything else I see with the motor (front valves closed, cam lobes pointing at 10 and 2, piston at the top of the cycle) I'm sure that that is accurate. 

 

I don't want to force anything in for sure. The distributor is installed correctly based on being lined up with the tang correctly. I guess I can move around the wires but don't want to do that unless it is absolutely necessary. 

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You could be at 180 deg TDC. Remember this is a 4 stroke engine so the pointer will indicate TDC for both the # 1 and #4 cylinders. The best way to be sure is to have the valve cover off and look at the cam lobes on the #1 cylinder. They should be pointing up in a V pattern, not down putting pressure on the rockers.

 

Also, from what you said, it sounds like you "verified TDC" by finding the pointer and marking it. That's not how you verify TDC. You verify TDC by turning the motor until the #1 piston comes up to it's full height, as measured either by sticking a long screwdriver in the #1 spark plug hole, or by dial indicator with the head off. I usually "zero in" on TDC by rocking it back and forth between 5 deg BTDC and 5 deg ATDC.

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You could be at 180 deg TDC. Remember this is a 4 stroke engine so the pointer will indicate TDC for both the # 1 and #4 cylinders. The best way to be sure is to have the valve cover off and look at the cam lobes on the #1 cylinder. They should be pointing up in a V pattern, not down putting pressure on the rockers.

 

Also, from what you said, it sounds like you "verified TDC" by finding the pointer and marking it. That's not how you verify TDC. You verify TDC by turning the motor until the #1 piston comes up to it's full height, as measured either by sticking a long screwdriver in the #1 spark plug hole, or by dial indicator with the head off. I usually "zero in" on TDC by rocking it back and forth between 5 deg BTDC and 5 deg ATDC.

 

In all due respect, if you were able to read my other comments you can see that I followed several methods to find TDC including the ones you mentioned. You can see the pics of the cam lobes above. The notch in the pulley just verified everything that I was seeing visually. 

 

It's really the shape of the tang that I am matching up the bottom of the distributor to which is making the rotor point to #4. 

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Pull the #1 wire and put in the #4 spot on the cap. Arrainge the others 3, 4,2 counter clockwise and you're good to go. If you are 180 out this will fix it. The point is is doesn't matter where the distributor ends up as long as it's under one of the wires... this then becomes the new #1.

 

 

We try to keep all the distributor spindles installed the same as this makes distributor and rotor pointing directions and comparisons between them the same. Everyone on the same page.

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Found a gasket to work and here are multiple pics of the engine at what I believe is TDC. Again all signs point to TDC but it would be great if these pics would show it as well. I don't believe my cam sprocket looks like the ones I see with the V notch because it doesn't have it. 

 

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OK, so this is an L20b, so first I would ask if there is a reason you are using #1 dowel hole/mark for the cam gear, normally the L20b uses #2 dowel hole/mark.

Have you turned the engine since you installed the distributor drive shaft and oil pump?

As Dmike said, as long as the lobes are at 10am/2pm, and the crank is at TDC, where ever the rotor is pointed will be number 1 spark plug wire, your rotor doesn't seem to be pointed where I would expect it to be pointed, that is why I asked if you have moved/turned the crank for any reason since installing the dist. drive shaft/oil pump drive shaft.

I personally have never looked for the notch that the folks here are asking about, I just set it up by eye, as I know what it is supposed to look like, but everything has to be right for it to start, oil, gas, power to good coil, wires in the correct places, and power to the coil when turning it over.

The lobes look close, don't see a crank photo, and I am used to seeing the rotor pointed at 4pm looking at it from the side, like when you look down the dist. hole to see it pointing at 11:30.

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Found a gasket to work and here are multiple pics of the engine at what I believe is TDC. Again all signs point to TDC but it would be great if these pics would show it as well. I don't believe my cam sprocket looks like the ones I see with the V notch because it doesn't have it. 

 

zD4qx9wl.jpg

6bAwMVWl.jpgRMpr38fl.jpggbK4Yddl.jpgoD6eS2ml.jpg

You have   "U" shaped notch.  Looks close, use a very bright flashlight and look through the hole in the cam gear to verify the notch/ mark on the cam tower plate is correct.

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