Yep, looks like the cap is missing the carbon button. If it's missing then it's time to replace the cap. I would replace the rotor too as it may have been spark jumping

The terminals inside the cap look fine. That's normal condition after it runs a while

The rust particles inside the cap (and on the rotor) look suspicious, but can be cleaned off with soap & water


with that type of distributor cap (screw down) it can be put on crooked, so visually check the fit before tightening the screws

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Quote:Yes, small amount up-and-down shaft play is normal.

But there should be no side-to-side play. Because if there is, the air gap might get too small, with metal-to-metal contact. In my experience it will still run fine even so. But Rallywtit's experience was:
Quote:The trigger is the star-shaped wheel attached to the shaft

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Due note mine started missing around 4500 it would rev with a steadily increasing miss and wouldn't go beyond 7200.

By contrast when the dizzy is in good nick the motor will rev to 8600. When the A12 was in the car on occasion it would see 9100 rpms, this was with a stock un-modded matchbox style distributor.

I ran a track day in May and the car developed a very very slight miss toward the end of the day. The vacuum advance pull rod screw was loosening up. This mounts to the plate that acts as the upper bushing, this was enough to cause an issue. My semi solid motor mounts and a constant diet of 5000-8100 rpms comspiires to buzz bits loose. Loctite, safety wire, lock washers and nylock nuts are the order of the day.

Tom

ill check the vacuum tonight, i love to give my little ute a hard time also, didn't even think about it shaking and rattling things loose

so im up for a new cap and a new rotor? is it easier to replace the whole dizzy?

thanks for the help guys, ive learnt a lot hey :)

I see no reason to replace the whole distributor
* If the rotor button is missing, I would replace the cap & rotor
* If the button is still there, I would instead clean the cap & rotor in the kitchen sink with dish soap & water, then let dry overnight


Also, check the timing so you can see if it is correct. No tools are required to check this. If it's too far advanced, the engine won't be able to rev very high under load


Vacuum is not the what rallywit was talking about. He said:
Quote:If either screw is missing it will cause highly erratic spark timing

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problem solved!!! I tried to buy a new dizzy cap but i couldn't get one over the weekend (c22 vanette screw type) i brought a generic one from supercheap and simply pulled the button out of the new one and put it into mine and hey presto I have top end power again :) :) cheers for the help guys hope this thread helps anyone else having dramas