TR6 69 TR6 distributor/vacuum advance/retard help

[ichthos]

Since I was getting off the subject of tuning in my last post, I decided to just zero in on the the distributor and vacuum unit. So, I have a few questions. 1)Does the cam in the middle of distributer that controls the opening and closing of points ever wear out or wear unevenly? 2)Is this easily reapaired? 3) The vacuum unit itself seems to be very loose to me - is this normal? 4)How can you tell if the vacuum advance and vacuum retard are working? 5) How easy is this unit to repair? 6) If the vacuum unit is not working, do you normally just buy a whole new distributor or get it rebuilt? Any help would greatly be appreciated.
Kevin

 

[Tinster]

Kevin,

I had my dizzy rebuilt by Jeff Schlemmer
jschlemmer1@mn.rr.com

Jeff did an excellent job. My vacuum ears are
both "loose" and wiggle also. I think this must
be normal.

You could e-mail jeff and I'm sure he'd be glad to
help you out with questions.

I still do not know which dizzy ear is retard and
which is advance.

tin

 

[vettedog72]

1)Does the cam in the middle of distributor that controls the opening and closing of points ever wear out or wear unevenly?

Not likely but the screw head in the middle of that cam needs a drop of oil when ever you change the engine oil (its the lube system for the advance)

2)Is this easily repaired?
I have not seen a cam for sale but it would be easy to replace I DOUBT IT IS NECESSARY though


3) The vacuum unit itself seems to be very loose to me - is this normal?

Not on my '74TR6 but i cannot remember how it fastens to the dizzy body; some one else may help you with the looseness.

4)How can you tell if the vacuum advance and vacuum retard are working?

with the motor running (idle) just pull the vacuum hose off and cover the end that goes to the manifold. The motor should significantly slow down may even stall. When the vacuum line is reconnected the motor will speed up.

6) If the vacuum unit is not working, do you normally just buy a whole new distributor or get it rebuilt?

NO. You can replace the dashpot.

 

[TR3driver]

1)Does the cam in the middle of distributer that controls the opening and closing of points ever wear out or wear unevenly?

It's worth checking the peaks of the lobes, where the rubbing block rides. If it's worn, you'll see a ridge since the rubbing block doesn't cover the entire face of the lobe. But it's very rare to have significant wear here. A slightly more common (but still very rare) form of damage is rust pits on the lobe, which will wear the rubbing block quickly (requiring frequent readjustment of the points).

2)Is this easily reapaired?

I don't know of anyone supplying replacement cams; but changing the cam is not too difficult if you can source one (from another distributor perhaps). <div class="ubbcode-block"><div class="ubbcode-header">Quote:]3) The vacuum unit itself seems to be very loose to me - is this normal?[/QUOTE]The 69 arrangement is rather unique as I recall; the distributor was originally designed to have a vernier adjustment on the vacuum advance, but adding the retard required removing the vernier. As a result, the vacuum units are a bit loose. <div class="ubbcode-block"><div class="ubbcode-header">Quote:]4)How can you tell if the vacuum advance and vacuum retard are working?[/QUOTE]If the retard is working, you can pull it's vacuum line off at idle and see/hear the engine rpm increase. If the rpm doesn't change, put your finger over the line to see if vacuum is being supplied. If vacuum is present but the rpm doesn't change, likely the retard capsule is bad.
The vacuum advance does nothing at idle, so it's a bit harder to test. Connecting the retard line to it is one easy test; the engine rpm should increase sharply. But it's best to test it with an outside source of vacuum, like one of these :
https://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92474<div class="ubbcode-block"><div class="ubbcode-header">Quote:] 5) How easy is this unit to repair? [/QUOTE]The vacuum units are basically not repairable by a DIY.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] 6) If the vacuum unit is not working, do you normally just buy a whole new distributor or get it rebuilt?[/QUOTE]Sometimes the vacuum units are available separately; but a quick check of Moss' website shows only the advance unit, not the retard. However, my FLAPS can send them out to be repaired.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Any help would greatly be appreciated.[/QUOTE]IMO, the retard is fairly non-essential. If it doesn't work, you can opt to just leave it not working, and use the "static" timing figure when setting the ignition timing. You'll also need to adjust the idle rpm.

The engine will actually run just fine without either of the vacuum modules working; so if you are working on operational problems, this is probably not the right place to look. The vacuum retard's only purpose is to reduce emissions at idle; and the vacuum advance was actually deleted from later US-spec TR6. All the advance does is give you better gas mileage and slightly improved part-throttle response.

 

[TR3driver]

I still do not know which dizzy ear is retard and which is advance.

TR6 dizzy turns counter-clockwise, right ? That would mean that, with the modules on the side towards you, the advance is on the left and the retard is on the right.

But it should be trivial to supply vacuum to one and see what effect it has on engine rpm. If supplying vacuum slows the engine, that's the retard. If supplying vacuum speeds the engine, that's the advance.