Vacuum capsule on distributor question...

[RoadRacer]

I noticed on my car the vacuum line going to the capsule is blocked off with a screw and not being used. What is the function of the capsule and should I reconnect it? The car runs very good the way it is. Why is it blocked off?

[danaspider]

That is the vacume advance and contrary to some thoughts it is not "just for emissions" It advances the timing during acceleration and provides over all improvement in performance and operation. So yes it should be hooked up. Why was it disconnected? Probably the vacume disk is cracked and instead of replacing the vacume advance, someone plugged the vacume line to prevent a leak.

First check, hook a vacume hose to the advance and suck on it and see if it draws very easy. If easy then the rubber insert is leaking.

If holds pressure then you will see the little linkage move and the rotor advancing.

A new one is about $35 or so. Held on by 3 screws onto the bottom of the Distibutor. A bit of a pain to remove, but can be done with out removing dizzy. Just use the same screws, as if you loose longer than normal they will drag on the inside parts of the dizzy. I used allen head screw on mine, becuase I got tired of trying to find the flat head while working upside down in the mirror.

Once repaired reset / check timing.

Hope this helps

[ga.spyder]

I replaced mine not long ago and there was a noticeable difference in acceleration,although not drastic.I tried to do it w/o removing the dizzy,but it didnt work for me.The dizz was easy to remove and only took 1 hour or less to complete.I was a little confused by the timing,it should be +10 deg. Check your manual to be sure you are setting to the right mark.
Craig

[RoadRacer]

Thanks, I will check the vacuum and then replace hose. I really appreciate the help I get on this forum.

[racydave]

It should be -10 degrees (BTDC), and you shouldnt have vacume at idle for the advance, only when throttle is opened!

[So Cal Mark]

10btdc is correct, but what's up with the -? In my world, - would mean atdc

[RoadRacer]

I checked the vacuum and it is only 5 psi. I guess I have to replace the capsule. If I take the dizz out and put it back exactly as I took it out I think it will work...... I will still check the timing out, I have an old sears light that works great.
Thanks for the help.

[racydave]

The engine makes the vaccum, the advance unit reacts to it. Does the unit hold suction, and move when applied?

[TJC]

That is the vacume advance and contrary to some thoughts it is not "just for emissions" It advances the timing during acceleration and provides over all improvement in performance and operation.

Although correct, it is indeed not quite an emissions device, it is not used during acceleration and, therefore not used for performance. Quite the opposite, actually. It uses a type of vacuum signal called "ported" vac from a special port on the carb (just above the throttle plate).

It is meant to bump up the advance of your ignition timing during light load (i.e., part throttle) operation such as highway driving in order to increase the engine's efficiency and thereby increasing fuel economy. However, due to knock concerns, it is not employed at higher loads.

[RoadRacer]

Unit does not hold suction, I pump it up and only goes to 0-5 psi. If it holds at 5 is it good?? After I replace it,
how can I check timing? Does the water neck need to be removed? What do I need to do to be able to see timing marks?

[danaspider]

If you pull a vacume on the vacume advance and it holds, then the diaphram is ok. If it does not hold vacume, then it is bad and needs to be replaced.

Not sure of the amount of vacume, never actually measured it. Are you saying that if pull more than 5psi it leaks down?

To check timing will need a timing light. No removal of parts required.

[mdrburchette]

Your timing marks are three raised lines on the timing cover. You may have to clean a bit of road grime off but they should be visible:

[RoadRacer]

I do not have three little marks on my timing cover.
My timing cover is gray and has no raised marks like picture shown.
Are the 82 different?

[So Cal Mark]

82s have the timing pointer on the opposite side of the engine, on a tab rather than the cover

[RoadRacer]

I bought a workshop manual from international and it it s not too helpful. For the price you would think..... The pictures are dark with not much detail. Any good manuals out there? This manual has nothing helpful as to where to look. I am looking for a tab on the other side and see nothing with numbers. Any suggestions?