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Distributor question/issues


ElCimino

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Ill start with some info about the car then my question. '73 240z L24, round top su carbs, 4speed transmission, headers, electronic ignition. Now to my question/problem. With a timing light connected to #1 cylinder wire and the car at idle the tab shows slightly below -7. I could be wrong on this but from what I've read the marks are from low to high -5, 0, 5, 10, and 15. Please correct me if I'm wrong on this but regardless the timing was showing below the lowest mark. This is only achieved by having the distributor turned as far advanced as possible. Any turn to retard the timing would cause the car to idle roughly and die. I found some pictures while searching that showed my plugs were in the right order but were one plug off to the left if you are looking at the distributor from the drivers side of the car. So I moved them forward one each and the retarded the timing to compensate for the change. The car would run with this change but only if I now turn the timing all the way to retard. The timing marks at this setting shows a little above the +15. When I advance the timing the car idles rough and the dies. I wouldn't really care if it ran fine but it sounds like it just needs a little more advance or retard in either configuration to run smoothly. From what I can tell the po installed a reman distributor (card one?) and added a pertronix electronic ignition module. The coil doesn't have a name it's just black. There is a ballast resistor. Everything functions it just doesn't seem right. Any info is welcome. I can take pictures this evening of anything you need.

Thanks,

Chris

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Set engine at top dead center then check to see if the timing mark is at "0" as a first step (bottom right corner of big photo below).

Then lift distributor and look a the end of the spindle that drives the distributor for the 11:30 angle with the smaller 1/2 facing forward. (first photo below)

Once your timing mark and distributor are verified (mechanical timing) then move to electrical timing (plug order and distributor rotation)

IMG_9916.jpg

Ztiming.jpg

Edited by Blue
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Thanks for the reply Blue. I will check that this evening. From memory I don't think my rotor is in the position that your second picture shows. Ill double check this. To check the timing chain ill need to pull the valve cover and get a new gasket?

I just saw your post with the timing marks so I'm either just below zero or above the +20 depending on the configuration of the spark plug wires connected to the distributor.

Thanks

Chris

Edited by ElCimino
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No need to pull the valve cover. We'll assume the chain is ok.

Just get the piston #1 at the front of the motor in it's highest point (remove plugs and turn crank with a 27mm socket by hand)

Once at Top Dead Center, confirm the timing mark is at 0 on the damper pulley and that the distributor driving spindle end is at 11:30

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Here's what I have. All pics taken with #1 TDC. The key for the distributor looks like its running parallel to the engine. Not sure why all the pics are on their side.

post-29173-14150824814768_thumb.jpg

post-29173-14150824813433_thumb.jpg

post-29173-14150824814188_thumb.jpg

Edited by ElCimino
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Great photos. The crank-driven-spindle that connects the oil pump to the distributor is clearly retarded thus your -7 degrees.

You can correct this by dropping the oil pump and rotating the shaft. The pump has 4 bolts that hold it to the timing cover. sometimes the sway bar may be in the way so you may have to move it.

Another way is to manipulate the plate under the distributor by drilling new holes and oval-ing existing ones or by changing the bracket that holds the distributor.

I recommend just dropping the pump and spindle with the engine at TDC and follow the procedure that i will post in the next message as an attachment.

The bottom line is that your electrical timing is retarded so you need to advance your timing.

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Thanks Blue! This explains a lot. I will adjust this ASAP. (Probably Tuesday) Thanks for all the pictures and information. I'll post results once the adjustment is complete. I got my car as a toy/project in February and the ignition has never seemed right. Just because I'm curious is this something caused by human error or is it something that changes over time from engine wear? Knowing the po of my car I'm guessing human error.

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No worries... these are tough cars and have sustained worse abuse than a mis-clocked distributor! You will enjoy more power after tuesday!

btw when your distributor is at its correct advance, your car will idle faster so you will have to reduce idle speed at the carbs.

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We dropped the fuel pump out and rotated the distributor shaft to how the service manual shows. I've got the car running however i still have to have the distributor pushed as far advance as possible. In this position the timing light shows about +7 at idle (700rpm). Would tuning the carbs effect this at all or should I just be happy that it's running again?

I have watched the ztherapy carb tune video twice through. I don't know if he mentioned and I forgot but I would like to clarify turning the screws that adjust the air mixture clockwise (tightening) is more air and counterclockwise (loosening) is less air? Right now when I lift the piston in the carb the rpm's go down. When I put the unisyn on the rpm's go up. Does this mean i'm too lean? If this is true then it feels a lot like the last time I tried to tune. I had to have the jet nozzles 4-5 turns open to get everything to work. This takes me to my next question. I installed a clear wix filter before the fuel pump. When the car is running there is very little fuel flowing through it. After I've turned the car off it will slowly fill back up. Is this normal?

Edited by ElCimino
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