Distributor mod for mechanical advance?
 

is there a modification to make a vacuum advance distributor mechanical only advance?

Ummm, disconnect/plug the vacuum line? ;)

lol oh yeah

There is a little switch underneath the impulse-plug on the side for "Vacuum or Mechanical". Just flick it. :D

Don't tell us what kind of 911, or distributor, you have. :rolleyes:

For Mechanical advance only, the vac pod is removed, the advance plate is locked, the springs may be changed and the weights might be ground a bit to change centrifugal properties.

The distributor has to come apart for each manipulation, then checked on a special machine or installed on the engine (Stroboscope) and checked for the correct curve for your CR, octane and general air temps.
Cost to do this is about $3-400
Quite involved and not to be taken lightly. SmileWavy

Isn't it actually a vac retard rather than an advance.

The car has been sitting in storage in Nebraska for 3 years. I have forgotten a lot of things about it that I used to know pretty well. I believe the dizzy is off a 2.4

+1 on Gunter's post.

It would be helpful if you would let us know more about what size of motor, type of fuel delivery (ie. Carbs, MFI, CIS, etc.) and is the original dizzy or a replacement?

My question is why would you want to back convert to a mechanical advance?

its a 2.2 rebuilt in a 7R case. Just got PMO carbs getting ready to install them. I think the distributor came off a 2.4 or something. I bought it used.

I had Jerry Woods do mine. Re-built and re-curved for early E-cams at same time so all slop etc. was taken care of. Think it was in the neighborhood of 3-400 bones. Good work, no more wandering in the timing.

its not a DIY thing then. Thanks all for your posts and help.. I will either have it worked on by Jerry Woods company or someone or I will just get the electronic ignition from clewett

For a recurve, you'll have to supply details about your engine like CR etc.
If you go with electronic ignition, a correct setting is still required. SmileWavy

Detonation is the enemy. :(

I want to say this dizzy has a vac retard on it. Once I get back to Neb. in 2 weeks and I can actually look at it again it will be much easier to ask these questions.

If it is from a 2.4 ltr, it will have the vacuum pot on it. The PMO intake manifolds have provisions for the vacuum lines so I would just have the dizzy recurved for your motor's specs and retain the vacuum set-up. The bushings and everything are normally replaced during the rebuild so it will work really well when you get it back. BTW, if you replace the points with an optical system you wont regret it. You probably can have this done by Jerry or by whom ever you get to do this work.

The electronic ignition is good but it will be more expensive and will require more modifications to the car (clearancing the case to accept the trigger pully and modifying the wiring of the car). Additionally, you will need to change your spark plug wires to ones that are more compatable with the crank fire set-up.

A question you should ask yourself is...How long am I going to live with the engine set-up that I am going with now. If it is going to be a while I would just get the dizzy re-curved. If you are expecting to change the engine by punching it out, increasing CR, changing cams etc. Then it may be worth while to just convert to the crank fire set up now. If you are planning on racing or autocrossing the crank fire set-up may bump you into a different class (just something else to consider).

Don't the 2.4 and 2.7 L dizzies have vac retard only?

I think if you apply suction to the line and the revs fall it's a retard. If they rise, an advance.