Zed Head

What is going on in this picture? It's not obvious (to me).

It's already been through BaT before. I almost asked why the guy was selling it if it was the "right" Z. But, not really my business. https://bringatrailer.com/listing/1973-datsun-240z-198/ This 1973 Datsun 240Z is said to have undergone refurbishments in 1985 and 2010, and it was purchased by the seller on BaT in July 2022. lucasphilips (The Seller) This author's likes: 8 Thank you all for viewing. I am offering this 1973 Datsun 240Z after owning it for two years, and getting a ton of enjoyment out of it. I spent about a year searching for the right 240Z. I bought this one because the color is so unique, and the meticulous documentation that came with the car indicated the prior owner had taken proper care of it.

Set the points gap by getting the points rubbing pad on the peak of one of the distributor cam lobes and setting the gap. Once the points gap is set it does not need to be touched again. You can rotate the engine and the distributor body wherever you want and the points gap will not need to be reset. Then find out where the rotor is pointing with the #1 piston at TDC, compression, +/- 0 to 10 degrees (use the timing mark on the damper pulley). Then set your #1 plug wire at whichever cap terminal the rotor is pointing at. It should be ready to start. If you get all of that done but cannnot use the screw in the pedestal to lock the distributor body down then you'll need to reset the oil pump. But you need to find out where the rotor points at TDC, +/- 0 to 10 degrees, advanced first. Setting points gap. Start at 1:00. https://youtu.be/BC3nmuXdEuI?feature=shared&t=61

I don't think that the points will open with the rotor between electrodes, if the parts are put together correctly. This is why all three things need to be done at the same time. If the rotor is between plugs it means that you need to rotate the distributor body. I don't think that you actually asked the question about the rotor between plugs. Which might be why no one answered.

This like the Adam Sandler movie "50 First Dates". Each day is like the one before never occurred. You have one of the three. Do the other two. Side note - I finally discovered how to do a multiquote from multiple pages.

Here's an old thread with good stuff in it. Excellent picture of lobes-up by Cliff/unseen. Just realized that I have no memory of the ignition timing mark on the damper pulley ever being mentioned by Mr. Vancouver. That's the other indicator of TDC. Get the cam lobes up, rotate the engine until the timing mark is at zero. The adventure is in trouble if TDC compression cannot be found with this information.

You're right. I thought the other lobe might not be visible behind the timing sprocket but lost track of the actual configuration, even though I had pasted the rusty cam picture earlier. I dug up an eBay picture for reference just now, pasted below. He wore me down, I should have checked. Not sure how two cam lobes sticking up can be misinterpreted. Still, all of the advice given by everybody in all of the numerous posts is good. He just needs to get some of it done. The picture below shows the #1 cam lobes. The piston is not at TDC on compression stroke.

They look up, so you're on compression stroke. but which spark plug electrode is the distributor rotor pointing at when you are at TDC on #1, and are the points close to opening, either about to open, open, or just closed. You need to get those three things happening at the same time so that spark will be correct for all of the cylinders as the engine turns. Compression stroke on #1, distributor rotor pointing at #1 electrode in the cap, points opening. If you can take a picture like the one above but with the distributor included, one with the cap on, one with the cap off, and with your plug wires identified in the cap that will tell a lot. We need to know where the rotor is pointing when #1 is at TDC on compression. And we need to know that the #1 plug wire is attached wherever it is pointing. And that the points are open. p.s get everything set up with the valve cover and the distributor cap removed. Rotate the engine by hand and watch the parts move. You'll be able to figure out for sure when the points open on the #1 compression stroke and place your dist. cap wires correctly. Then replace the valve cover and try to start.

Actually it can be off by quite a bit. It would probably start with initial timing set from -5 to 25. A range of 30 degrees. But there's a lot of other things that are unclear. You never answered the question about where you were spraying the starter fluid. You haven't removed a spark plug to see if it was wet. You haven't verified that the timing was close to correct, or if it's even set to the compression stroke. If you're firing on the exhaust stroke as, suggested by several, you probably won't hear a pop because the flame will just shoot out the open exhaust port. You're looking for a simple single answer but there are many things that have to be right at the same time. You need to create a check list then check each item. You got spark, which is something, and you installed different carbs. Lots left.

Yikes! https://bringatrailer.com/listing/1977-datsun-280z-109/

Rotating the distributor body will not affect the points gap. I talked about when the points should be open in Post #11. The points open and close each time the distributor cam lobes go by as described in the video I posted. They open and close about 15,000 times per minute at 5,000 RPM. Rotating the distributor body changes the time that the points open for each cylinder, in relation to the piston position as it moves up and down in the cylinder. Rotating the distributor body is called "setting the timing". The shaft with the lobes stays attached to the camshaft but the points move in relation to the distributor cam lobes because they are attached to the distributor body. Rotate the distributor body as you watch the points and lobes.

Another.

This video might help. I copied from the "point" where he talks about the rotating shaft. Watch this video and others from the sidebar.

The stuff in Post #11 will answer the question about the oil pump. If you do the things and the rotor is pointing the wrong way then you'll know the oil pump is off. Still might not need to change anything. Just get the timing mark and the points opening and the rotor alligned with #1, then put the rest of the wires in. But #11 answers many questions. Do #11 (make sure the cam lobes are up), take pictures, come back. Worst case is the lock down screw won't have a hole to thread in to. Then it can be decided whether or not to reset the oil pump. Progress is slow but it is happening.

I wrote a bunch of stuff but will just say instead that idle and pressure tests in the driveway might not be replicating the loss conditions of driving. Loads and temperatures are different.

For where you're at right now I would do the above. Whenever you try to start the engine and nothing happens you suck raw fuel in to the cylinders. Do the above, pull a spark plug and make sure it's not soaked with gasoline, then try to start it with starting fluid if the plugs are dry. When you spray the fluid in to the carburetors make sure the carbs are open so that the starting fluid can get in to the intake manifolds and cylinders. Also consider the choke.

To put the second part above in to useful terms - Rotate the engine until the timing mark is at 10 degrees on the damper pulley, on the compression stroke. Then loosen the distributor clamp and rotate the distributor until the points are just about to open. Make sure that the rotor is pointing at the #1 position of the distributor cap. Clamp it down and try to start.

Yes. It's common to rotate the distributor while trying to start an engine with new parts, to get the ignition timing close enough to start. Unfortunately it's usually done by people with experience who understand ignition timing. Another thing that's often done is to watch the points as you slowly rotate the engine by hand to see where the timing mark on the damper pulley is when the points open. Spark happens when the points open. Rotate the distributor so that the points open at about 10 degress advance, and make sure that the rotor is pointing at the #1 cylinder electrode. This will get the igntion timing close enough to where the engine should start and run. Then you can set the timing correctly using a timing light after the engine is running. Spark plug wire order is 1-5-3-6-2-4, in counterclockwise rotation.

The original high miles engine in my car used to leak coolant from the right rear area of the head/block interface. It only leaked when cold and sealed up after the engine warmed up. Took me a while to figure out since there was no steam or odor from hot coolant boiling away. I noticed some staining from where it flowed after escaping. It was a bad headgasket but the bad part was only a coolant sealing area. The port to the heater core is back there also.

Where are you spraying the spray and what is it? Is it real starting fluid? Have you measured cylinder pressures? Compression. Have you pulled a spark plug and examined it? Maybe you flooded it.

You said old rebuild in your first post. Were you expecting better? Sounds like an old used 280Z engine. These engines will continue to run well even as they burn lots of oil. What are you trying to determine? I'd pull the valve cover and check the timing chain for wear (notch and groove), the oil spray bar for damage (if it has one), and the rocker arms and cam lobes for wear. While you're there check and adjust valve lash.

There were only two compression ratios for the NA L28's. 8.3 and 8.8. A stock N42 block should have either an N42 or N47 head. That would give the 8.3 CR. Your pressure numbers seem low but the adapters or length of the hose to the gauge can affect the ratio. More adapter or hose looks like more combustion chamber volume. What do you mean by "air flow meter at the intake"? Are you doing your measurements with the intake manifold removed?

Curious - are you getting new rocker arms? Word is if they have any wear you should get them resurfaced. The old wear won't match the new cam. New cam needs new wear pad. Again, just regurgitating...

Funny, looking at an actual rocker arm it seems almost reasonable to just use the base circle change directly. Because the contact pad is almost over the valve stem. And there is some room on each end of the wear pattern for error. Seems like you could take your 1.55 mm number and just fudge it based on the existing wear pattern, adding a little bit for the relatively small distance the lash pad is extended from the rubbing pad. OR you could just stick a 1.55 mm shim under the 300f base circle and take a measurement at the lash pad. Since it's getting bigger. Replicate the L490. One question for you would be whether or not the valve tips on your current setup have been ground in the past after a valve job. Apparently the good machinists do that so that all of the lash pads are the same size. From what I've read here on the old forum. So Diseazd's recommendations might not work well since it's probably based on standard valve sizes. Not an expert, I just like to talk about things.

You'll be walking in circles if you let your leg get pulled like that.