Guest bastaad525 Posted November 13, 2004 Share Posted November 13, 2004 Just curious about something. I'm running an '81 CAS setup, which also means I'm running the 'blank' distributor (it has no internal components when you remove the cap, just the rotor on the shaft). Now... on this setup, you adjust the ignition timing by adjusting the position of the CAS in relation to the crank pulley, unlike just about every other Z where you rotate the distributor itself to change the timing. So, why then, does the '81 'blank' distributor, also have the ability to be rotated around in the same way as any other distributor? It has the same two lock bolts holding it down, and they pass through two wide slots on the base of the dizzy... loosen them and you can rotate the whole thing quite a bit... I estimate at least 10-20 degrees. And yet... doing so seems to have no effect on the ignition timing at all. I can sweep it through it's entire range of movement with the car running and using a timing light to monitor and the timing stays still. But I figure... they wouldn't have cast the 'slots' into the distributor shaft/base where the bolts go through, if there was no purpose behind rotating it, instead they would have just made two bolt holes and left it un-rotatable. The casting for the for the 'blank' is one piece and specific to this model only, so it's not like that part of the dizzy is a universal part used on all models. So, can anyone tell me why they did this? Is there any point to rotating the dizzy one way or another? Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted November 14, 2004 Share Posted November 14, 2004 adjustment would allow for being able to line up the rotor with the contact in the distributor cap.this should be checked during engine assembly.i have a 81zxt in my 77.what i want to do is use the nissan cas to run an aftermarkit efi system. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 15, 2004 Share Posted November 15, 2004 so does it make sense that adjusting it seems to have no effect? or would it be having an effect more subtle than I would notice? I've adjusted it before... so I have no idea if it's lined up now. Quote Link to comment Share on other sites More sharing options...
drzed Posted November 17, 2004 Share Posted November 17, 2004 It probably won't make much difference at idle but maybe under high load / high RPM conditions it might. To adjust it properly I believe you insert a small rod (gas welding rod works well) into the #1 lead hole in the top of the cap and line this up with the hole in the rotor when the engine is at 20? degrees BTDC - I don't have a factory manual with me so I am fairly sure it is 20?? Quote Link to comment Share on other sites More sharing options...
technicalninja Posted November 17, 2004 Share Posted November 17, 2004 Your not changing ignition primary signal when you rotate the housing (primary signal being controlled by the CAS). You will not affect the timing. You may affect the rotor to cap post distance. A serious miss-alignment might cause some ignition power loss as the coil would have to strike an arc in both the cap and the plug. Imagine 30% of available ignition system power being used up in cap. Bad for performance and hard on ignition parts. This is why Nissan slotted. Adjusting housing so rotor points straight at post 20 degrees crankshaft advance will work fine. 1 time adjustment. Rick Quote Link to comment Share on other sites More sharing options...
drzed Posted November 17, 2004 Share Posted November 17, 2004 OOPS... After consulting my nissan bible (factory manual) I have confirmed that it is actually set at TDC (on compression stroke of coarse!). This all confirms that you are using factory cap and rotor - the aftermarket cap I used didn't have the hole. Had to use my old cap to set the distributor and then change caps. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 18, 2004 Share Posted November 18, 2004 so rotate engine to TDC, stick a small rod thru the hole (my cap does have a hole in it in #1 plug), and make sure it lines up with the cap? Quote Link to comment Share on other sites More sharing options...
drzed Posted November 19, 2004 Share Posted November 19, 2004 The rod will go thru the hole in the cap and also the hole in the rotor - then bolt down the distributor, pull out the rod and you are done. Quote Link to comment Share on other sites More sharing options...
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