Not sure where to progress from here.

Everything had been fine and dandy with my new project 240Z until I noticed that I had noticeable loss in power compared to the first few days I had it. I didnt really take much notice but found myself flooring it more frequently just to move at a reasonable pace. Soon this lack of power was joined by a stuttering that started out pretty light but then started to grow "heavier". At first it seemed like the carb was running a little lean and then it started to feel like the car would turn off and then roll start itself again. The car just turned off while I was driving twice (felt like someone turned the key while I was driving. I just unplugged the battery and sat there for ~10 mins before it would start again). On the way home I had to keep revving high just to keep the car on and kept backfiring. When I got it home the second time it could barely make it up my driveway:
http://www.youtube.com/watch?v=Ii9HIvUyf0A
Compared to when it was running well:
http://www.youtube.com/watch?v=GMQqmtpQ8-Y
http://www.youtube.com/watch?v=A5e6WSfFx3s

In my mind if the problem was the timing chain or sprocket, Id notice immediately. The gradually worsening of the problem seemed electrical to me so I started checking things out and noticed that my car would only run fully advanced with the spark plugs wired in the correct order with the 1 plug nearest to the driver(thats how I got the car and it was running great so I never checked it out). The car had a Holley 390cfm before but Im not familiar with them so I switched back to round top SU's and also put in new NKGs, new plug wires, and another 240Z distributor with the Crane XR700 conversion since I thought the problem was electrical. Fired it up and its running the same as before...

Not really sure where to go from here. Im notoriously bad at diagnosing my cars problems so I dont want to go crazy if theres something simple im overlooking. Heres a vid from one of the rare starts today. Getting lean pops for some reason even though im 3 turns out and the chokes are pulled.
http://www.youtube.com/watch?v=xe9Ohx4NyAM

Any ideas?

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71' 240Z: HLS3040666

It freaked me out to see you climb into the "right" side of the car, and to watch the SUs on the "right" side of the engine! Not sure how you managed to get a mirror image onto YouTube ~ that's the first time I ever saw that!

The flashing back thru the carbs is a timing problem (ignition or valves) or a faulty intake valve.

Cam timing, valve adjustment, carb adjustment, ignition timing, vacuum leaks. Plenty of hunting ground available for you to explore there.

1. Check the compression to see if it differs btwn cylinders (which would show if a valve was cracked or over tightened so it didn't seat).

2. Check the timing to prove to yrslf that your 240Z is the only one in the world which requires the #1 plug to start at the back of the distributor.

3. Open the throttles and spray some starting fluid into one SU and immediately try to start it. If it works, you're starving for fuel.

Somebody else get in here with some advice, plz.

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1970 240Z

Sounds like your timing order is off in the dist, and its over-advanced to compensate.

- with the engine off set the front balancer to 0 TDC.
- look in the oil filler hole and make sure the first 2 cam lobes are pointing up (11&1 oclock).
- Pop the dist cap and the rotor tip should be under or close to the #1 tower.

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Bryan Little
Datsunzgarage.com

1970 240Z - enhanced F54 L28 w/P90, Weber DCOEs, 4:11 R200, Nissan T5 5-speed

Bryan ~ his #1 spark plug wire comes from the BACK of the distributor, closest to the firewall. He says when he wires his dizzy the right way (#1 at the front) the car won't run. I think his distributor shaft is in 180* backwards.

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1970 240Z

If the distributer shaft is in backwards it will still run like normal if the wires are hooked up 180 degrees off. This is a picture of it correctly hooked up.


240z firing order by Rob Olejniczak, on Flickr

The firing order is 153624 counter clockwise on the distributer.

I was the one the sold Porkbun the carbs, distributer, xr700, and intake manifold. Basically I unbolted the intake manifold from the head and left everything attached to it. It was running great when I removed it from my car a few weeks ago.

I advised you not to touch any of the carb adjustments until you got everything else right first and the would then only need a fine tune. They are not the problem. You should reset the mixture nuts to 1 1/2 turns out and then figure out the problem. Fiddling with the carbs because of another problem will only make it worse.

Do what Bryan said and get the cam lobes for cylinder 1 pointed up and then see where the rotor is pointed in the distributer. That is cylinder 1 for you. Sounds like it is where 6 should be. Is that right?

Follow Bryan's advice for timing to 0 degrees. You need to get the engine back to baseline settings everywhere to figure out what is causing your problem.

I agree that by gradually starting to run poorly sounds electrical, but I would do a cold adjustments of the valves at this point. It can eliminate that and needs to be done anyway before you set the carbs when it does run right. If they are out of adjustment they can cause really bad running like you were experiencing.

You should remove the front inspection cover and see if the cam timing is off. If it's going to jump a tooth it would probably be on the cam sprocket and you would see it here. The chain could be loose too. You should look and see.

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Rob
1971 240z

Frank: I recorded the video on my laptop which usually flips things around. I watched the video again and it was pretty weird to see. The only time ive gotten flashing back like that on this car was when I tried to retard the timing with the Holley. On my 260Z with the round tops it happened when the car was running lean but at least it sounded like the same car. Im going to try and get over to Autozone to rent out a compression tester and a timing light today so I can start checking things out.

I tried starting the car up with the distributor fully retarded all the way to fully advanced and it would only start when fully advanced and with the spark plugs reversed.

Datsun Z Garage: Im going to pull the radiator so I can finally get access all the stuff I need to turn the crank by hand.

rob240z: Im thinking the distributor shaft is backwards but im not sure if that would be the reason its no longer running. Looking at that diagram, my #1 plug starts in the 3 spot. Heres a of the setup the week I got the car:
https://picasaweb.google.com/flyingaero ... 0590848546


You did advise me not to touch anything until everything else was right but ont of the studs on my intake manifold was short/broken off and a carb couldnt bolt on. I ordered an intake manifold gasket and while I was waiting for it to arrive I decided to give everything a clean up. I now know the carbs arent the problem because they came off of your running car and on my car its running the same as it used to. I turned the mixture to 3 turns because Ive always seen the starting point as 2 1/2 and I was getting intake backfires so I richened the mixture a bit to see if that would solve the problem. Since the ignition and the fuel delivery werent the cause of the problem like I had originally anticipated, it has to be something else.

Ive gotten a few suggestions but where should I start? Id like to go from simplest to most difficult so I dont have to tear apart the engine if I dont have to. Im going to pull the radiator today and see if I can get the cam to TDC. I also think its time to get my hands on a good book to help me learn more about the L engines. The FSM sort of assumes the reader is already a mechanic.

Heres an album of what I did yesterday: https://picasaweb.google.com/flyingaero ... TZ5dXWkgE#

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71' 240Z: HLS3040666

Hey Porkbun,

The picture I linked is a generic 6 cylinder engine that shows the firing order. I should have said this before, in that picture the distributer is turned more counterclockwise than the L6. Number one post on the distributer is usually closer to where number 4 is on the picture, but the order is the same.

In the picture you linked with the Holley still on it, it looks like number one plug is in the correct place on the distributer and the shaft is not backwards.

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Rob
1971 240z

I think after looking at your original holley picture your wires are hooked up incorrectly and your distributer shaft is installed correctly. This is a picture of them hooked up correctly on a good running 240z.


DSCF4275a by Rob Olejniczak, on Flickr

Try to hook them up like this picture and then set the distributer neither advanced or retarded and then see what happens.

It seems like you have the plugs 180 degrees off and then another spot off clockwise.

If that doesn't work get the cam lobes pointed up on cylinder 1 and then see which distributer post the rotor is pointing to. That post is cylinder 1 for you regardless. That is what I would do if I was working on engine if someone took all the plugs off and couldn't remember where number one is. If you do that and it still runs poorly than you can rule out the ignition timing because it has been set correctly after that and it must be something else causing the poor running issue.

My guess is that is what will happen. You said this just started gradually happening when the distributer was hooked up in the referenced holley photos. So you can almost definitely rule out that that was the problem before. Wires don't just change their positions on the cap by themselves. You can probably rule out the carbs because the problem hasn't changed with changing to a known working setup. Maybe after you switched the carbs you installed the plugs incorrectly.

When you changed the carbs did you ever try to start it in with the wires hooked up exactly like this?

https://picasaweb.google.com/flyingaero ... 0590848546

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Rob
1971 240z

Oh man, you had me wondering if I had been counting the spark plugs/cylinders incorrectly the entire time. When I first got the carbs+distributor on, I tried wiring it the correct way and starting from fully retarded all the way to fully advanced and it wouldnt start. Did the same thing wired up 180 degrees off like usual and it would only start when completely advanced. Changed the plugs to NGK BPR5ES gapped to .40
(even though the boxes were marked 6) while the Holley was on the car and it didnt make much of a difference.

Just got back from autozone with a timing light and a compression tester. Im going to go out now to drop the radiator.

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71' 240Z: HLS3040666

What are you taking the radiator out for? If it's to turn the engine over there is far easier ways, even though taking the radiator out isn't that hard, just unnecessary.

If you detach the coil wire (the one that goes from the coil to the middle of the distributer) you can just bump the ignition over to line the cam up where you need it. That is what I do when adjusting my valves. You only need to take the valve cover off. If you need to fine tune the cam position use a monkey wrench on the cam to turn it.

That is the way I have always done it. Just make sure the car is in neutral first.

At this point the most important step is to get number 1 cylinder cam lobes pointed up and then see where the distributer rotor is pointing. That is easy and will tell you a lot.

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Rob
1971 240z

I dont really understand the process you described but ive already got the radiator and valve cover off. Could I have just turned this?

And by pointing up do you mean pointed up at 11 and 1 o'clock?

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71' 240Z: HLS3040666

No that is not where I was talking about. In your picture below the yellow circle is where I turn the cam with a monkey/pipe wrench. The red circles show the 2 cam lobes for cylinder 1. You want them pointed at 11:00 and 1:00 up if straight up was 12:00. That means cylinder 1 is in it's compression stroke with both valves closed. That is when the spark is fired on that cylinder and why in that position the rotor in the distributer has to be lined up with #1 wire on the distributer.


Screen Shot 2013-06-30 at Sunday, June 30, 2013 by Rob Olejniczak, on Flickr

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Rob
1971 240z

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71' 240Z: HLS3040666

in you top picture of you last post the cam lobes are almost in the right position. The cam needs to spin about 15 more degrees counterclockwise looking from the front of the car for the lobes to both be pointing up equally.

Another thing that makes the engine turn over easy is to remove the spark plugs so there is no compression resistance.

After you turn it a little more it looks like it will be pointing to the correct position 1. Where it should be and where it was in the picture of when you had the holley installed.

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Rob
1971 240z

Looks like I keep editing posts as youre writing a response. When I turn the crank pulley the side im cranking it towards becomes much tighter than the other and the other side becomes very loose. Is this normal? At first I thought I snapped the chain.

Two questions for rob240z that I thought up after that distributor picture: Did you run a voltage regulator with the crane? I also just realized that theres a dangling wire that went to the side of the points distributor. Looking at the electrical wiring diagram, it looks like its supposed to go to the negative terminal of the coil. Do you remember what you did with this wire or is it incorporated to the plug? Dont think this will get it running again but just curious

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71' 240Z: HLS3040666