Vacuum advance question

[dcraigbrown]

I have a 73 240z that I've been trying to get road worthy. After inspecting the ignition components I discovered the vacuum advance isn't working. After pulling it and giving it the suck test its not leaking but I can't come close to moving it with just lung power. The spring on the arm is so stout I don't know how the diaprham could ever move it. Is this normal? Hope its not trash because these things seem to be a bugger to find.

Any help would be much appreciated.

[Nissanman]

The vacuum motor may operate to mouth suction if it is serviceable, but it depends how good you are at sucking.

You can dismount the motor from the distributor and test it separately for correct operation.

If you have one, use a vacuum pump which will not only test the advance plate for full operation but it will also check if the vacuum motor can keep, or is losing, vacuum.

My guess is that the advance plate, which is supposed to run on small ball bearings, has seized.

This may just be due to a buildup of crud and such but it may also be because the "ball" bearings are now "cube" bearings:rolleyes:

You will probably need to dismantle the plates, clean and re-lube everything and maybe renew your balls:eek:

There is a small wire circlip under the points plate which holds it all together.

Once you remove that, BEWARE, bits might go everywhere:angry:

You will probably find grooves cut in the relative plates by the balls and rough, if not zero, movement of the sliding mechanism.

[justinr54321]

Dcraig, are you concerned about keeping it original and taking it to car shows? Because if not, a good upgrade would be to go with a dizzy from a 1979 280zx. It is electronic, and the number on the ignition box is E12-80, and is a very good upgrade, for you don't have any floating of the points at higher RPM's. Just my .02.

Justin

[xray]

If the diaphragm holds vacuum, then the problem may lie in gummed up/stuck/deteriorated roller bearings that sit under the vacuum advance plate. Mine was a little hard to move as well. Take off the points, disconnect the vacuum mechanism, and then remove the plate. Mine had a lot of debris between its plates , and after new lubrication of the bearings moves very easily....

Sorry I don't have pics at the moment.

[dcraigbrown]

Justinr,

I plan on going to electronic ignition eventually but trying to save money for the more serious problems at the moment. Do you know anything about the XR-700™ ELECTRONIC IGNITION SYSTEM? Its in the Motosport Auto catalog, PN 12-4001. It seems like a good deal at $120.

[justinr54321]

Justinr,

I plan on going to electronic ignition eventually but trying to save money for the more serious problems at the moment. Do you know anything about the XR-700â„¢ ELECTRONIC IGNITION SYSTEM? Its in the Motosport Auto catalog, PN 12-4001. It seems like a good deal at $120.

Dcraig, unfortunately, I know very little about it. However, I do know more about the MSD systems. I know I plan on getting the MSD 6AL electronic ignition system. It goes for over $200, but it has a rev limiter, and is multiple sparking at RPMs 3000 and lower to ensure complete combustion of the air fuel mixture, and one big powerful spark above 3000 RPM's. I do know that both igniton systems hook into your dizzy for reference for timing and what not.

MSD was one of the first to come out with electronic ignition systems, and has been doing it for a long time. Crane cams is just that, they make cams. In my honest opinion, I'd go with an MSD ignition system when you get the money because of this reason.

However, for the dizzy from the 280ZX, you can get one from a pull a part for like 40 to 50 bucks when you're ready with that also. I know I'm going with that dizzy and the MSD 6AL because I'm tired of my points floating at the higher RPMs.

I hope this helps.

Justin

[beandip]

I am running a '79zx Dist on my engine. I bought a second one at the bone yard for $25.00 from a '80 ZX . It was in great shape, Arne has it now on his Z. I am going to pick another when I come by one. All the ZX dist are the same accept for the turbo ones. It's the little black box , module, on the side that is different. So If you do find a dist on a '81-'83 pick it up and then find the 12-80 module and you are good to go. Be sure to get the mount the dist connects to that bolts to the engine block. your old part looks the same but it is not. Gary

[Curtis240Z]

I have the Crane XR-700 on both my wife's and daughter's Zs. It is definitely better than stock points and you can install it in your 240Z distributor. It does not have a rev limiter function. The Crane HI-6 has a rev limiter, but that is more money.