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blu260z

280Zx Distributor Half Out?

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Hi guys

I havent searched for this as I dont even know how to explain it! So I hope this makes sense..

After searching for a missfiring/running issue on my L26 I set the engine to TDC and came across what seems to be a 280zx distributor that is half out on its firing sequence.

Is this something that can be fixed. I am pretty certain my oil pump shaft is set correctly and I purchased a complete 280zx distributor including base.

 

20160708_205248_zpsvltscqc2.jpg

 

20160708_205401_zps8stcjeh0.jpg

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Are you sure you are at TDC?

Piston 1 top so stroke and cam lobes both pointing up equally?

Jeff

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Why is the coil fitted onto the block. It may be getting too hot as excess heat soaks from the block. Should be mounted on the body.

Just a thought.

David.

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I searched through the attatchment jeff but couldnt find anything. I am wondering if possibly my crankshaft timing is out by 1 tooth on the sprocket. The coil is just a trial for now.

Chris

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if it is in fact TDC. then it is not critical so long as you mark that position for ref, and the corresponding lead goes to No1 cyl the engine timing will still be correct when adjusted. fix next time if you ever take off the oil pump it is pretty easy to sort out

Edited by Linton

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When you say half out does that mean 180* , if this is the case & your TDC & oil pump shaft are in proper alignment plus you have your leads in the correct sequence the only answer can be that the Distributor has been dismantled at some time or other  & when put back together the rotor cam has been put back the wrong way which will put the timing out 180* . Have experienced this myself when rebuilding my Dizzy but lucky enough I marked everything down on paper as a reference.

If this is the case all you have to do is unscrew the retaining screw in the rotor cam withdraw the cam unit & turn it 180* & place it back, not forgetting to replace the screw of course !!!.

                                                      Regards : Alan.

Edited by zeds4ever

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There are three sections in the manual concerning the distributor. One in the tuning one in the rebuild and the other in the electrical sections. I just walked to the shed and had a look and your rotor position looks the same as this one on one of my engines.

post-103565-0-79198200-1468020238_thumb.jpeg

Linton is correct you can start at any point as long as the sequence is correct around the cap.

Jeff

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Thanks linton the oil pump is set correct but the it still seems to fall half way between 2 leads. I have moved the oil pump in both directions and it still lands halfway between. So instead of firing on 1,5,3,6,2,4 the rotor falls on 1.5, 5.5, 3.5, 6.5, 2.5, 4.5. If this makes sense? So I can only get the engine to run on max advance as this would be closest point the ignition aligns.

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Did this situation occur thru it's own doing , if this is the case check that the adjustment plate screw under the dizzy housing hasn't come slightly loose allowing the dizzy unit to move slightly. The other could be that if you have just fitted the dizzy into the motor you might have the wrong mounting base IE an 260Z unit as the tab where the dizzy increment timing plate bolts down to is slightly offset to the 280ZX  tab unit which is virtually at right angles to the base unit.

 

                                                              Regards : Alan.

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the shaft looks to be in the correct position according to the fsm, you may have the wrong base for that distributor I also had that Problem. the zx dist is different at the base but as I said ,it doesnt matter, if you can set the correct timing and not foul on anything your good to go, dont forget to set the air gap.

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Ok guys I spent the day doing alot of head scratching. The ZX distributor was a complete unit and has the 90deg base and appears to have not been rebuilt as it still has its original paint marks on the bolts. I checked the timing today and all is 100% so its making me think I may have jumped the gun and blamed the distributor. The engine is running a 350cfm holley which I purchased second hand. It ran a little rought but has got worse now it has a larger camshaft, I am now thinking it could be a "Frankencarb" bits and pieces from all different carbs chucked together. So I will send it off to be tested on a bench test engine, hopefully this answers my issues.

 

Thanks for your help guys

Edited by blu260z

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Is your mechanical advance free and working. Sounds like it could be the cause if the drive spindle is set correctly.

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Is your mechanical advance free and working. Sounds like it could be the cause if the drive spindle is set correctly.

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