Installing rebuilt distributor - idle before after timing?

[larry_in_socal]

All,

 

Long read...

 

I'll looking to change over distributors on my car. To begin, this is a continuation from my post " Rough and surging idle - suggestions " over a year ago.. back then I had got my the engine running but had a difficult time timing the engine... several replies pointed towards the distributor. And the game plan back then was to have my distributor rebuilt. I was also in the process of selling my house and moving to a new one, now that I'm all settled in ( for now!!!!) I'm sort of ready to start wrenching again. I bit the bullet and had my distributor rebuilt at Advanced Distributors, and that the rebuild distributor sat in a sealed box for almost an entire year..

 

Well now I'm getting around to replacing the current distributor with the rebuilt one, and the reason for my post today is to get my thoughts straight on what I need to do to change over the distributor. I just want to put down on paper (and in this post) what I think I need to do to make the change over as smooth as possible, and I will be basically listing down from memory the steps that I think need to follow. Before I list the steps here are the specifics to my engine and distributor.

 

The car is a '75 BMW 2002, non-tii, but I installed a 1600 engine (1565171+ ) so it's not the original. The head is a 118 head, and I adjusted the valves as a place to start. I have a stock manifold with coolant running through it and a Weber 32/36 with the following Carburetor settings:

 

Primary Idle 60, Main 140, Air Correction Tube 145, and F50 Emulsion Tube

Secondary Idle 55, Main 135, Air Correction Tube 175,and F50 Emulsion Tube

 

I'm running a bone stock mechanical fuel pump with a brass float that was adjusted using a gauge made of paper. I don't think that the Carburetor is the issue at the moment, as I think that the distributor that is currently on the car is not allowing a good timing of the engine, so here is where we are...

 

The engine runs fairly good, but the idle is off but it does idle, and revs pretty good for such an old engine. When I say off, the timing marks are dancing and shaking like a Hawaiian hula doll figurine on a dashboard.. lol .. I want to change the distributor to make the engine and idle smooth so I can work on other items, the brakes, CV, all other components so I can get the car road worthy, and that is the goal.

 

The car currently has 0-231-176-059 with 7mm copper leads and stock points, rotor and rotor cap, all Bosch components, that are in great shape. The distributor that I had rebuilt is a 0-231-181-011, and this was the distributor that came with the 75' engine that is currently in boxes in my garage. Also the car has the “clear-resistor” wire so I have a Bosch 0.9ohm coil, the car runs so I know that I'm getting spark, so that is not the issue.
 

I'm getting ready to install the 011 Distributor and when I finally get to opening up the box, here are the instructions from AD, .. “12-15deg BTDC @ idle w/o Vac”, with these instructions here is my game plan to install the rebuilt distributor:  Note: I checked with the rebuilder and the dwell was set at time of rebuild.

 

1. Place car at TDC on the compression stroke

   1. Check Flywheel marks

   2. Check mark at cam gear and valve oiler tube.

   3. Check that both valves are closed

   4. Check that distributor rotor is pointed to number 1 wire on cap.

2. Remove cap from old distributor with wires attached.

3. Remove distributor.

4. Install New distributor, noting where gear “swing” will place rotor to point towards number 1.

5. Verify that distributor rotor is approximately where the old distributor rotor was at.

6. This will get me at base timing and at least enough to get the car started.

 

I should mention that I should have at least had the car running (with the old distributor) to the point that the car is at operating temperature and that the idle (with the old distributor) was good.

 

So now that I have the new distributor installed, here is where I sort of need guidance...

1. With the new distributor installed, I should only tighten the hold down enough so that it doesn't allow the distributor to move, but enough so that I can physically move the distributor.

2. Remove the vacuum line from the distributor and or do not install it at this time.

3. On my Innova timing light, I need to set the advance to somewhere between 12-15deg, then with the car idling, turn the distributor till I see the TO mark at the flywheel, and that should be it.

4. Tighten the distributor hold down.

5. Install the vacuum line at the distributor.

 

I'm leaving out the idle adjustment do I set the idle after I time the car, or before? Also I was told to ignore the “BB” on the flywheel as the rebuild distributor would work best at setting it at idle. I think I'm on the right track, just sort of hung up on the idle before or after timing, the way I see it is how can I set the idle if the timing is off, so I think that I should set the timing first, then the idle, but the instructions are saying to set the timing off idle, so should I just check the idle first get it at around 800 rpm, (somewhere between 700 and 900 rpm) then do the timing?

 

Sorry for rambling on....

 

Larry_in_socal

[Stevenc22]

If the car currently runs, you can just use a sharpie or tape to mark where the rotor in the old distributor is pointing (in relation to the distributor body), then pull the old distributor, stab the new distributor such that the rotor points the same as the old distributor, put the cap back on and the car will fire up. Then you can fine tune it with a timing light.

Edited April 9 by Stevenc22

[OldRoller]

Get her idling 700-800, dial the Innova to 12-15 degrees, turn the distributor until you see the O/T just touching the driver's side of the hole. Dial the Innova to 25 degrees, increase throttle to 1500 and see if the O/T is centered more or less. 

Then adjust your idle, 700-800 at 1 to 1.5 turns out on idle air screw, or to best idle. 

The numbers might be a bit off, not familiar with the 1600, but it should put you in the ballpark.

BUT! I am always ready to be corrected...😎

Edited April 10 by OldRoller
Guided by wisdom of the Gurus

[Son of Marty]

If the car can hit the points in Oldrollers post relatively smoothly plug the vacuum line to the manifold and set the timing, reconnect the vacuum line then tune the carb for best over all power and you're good, what you don't want to do is screw with the timing and carb at the same time.

.

Edited April 9 by Son of Marty

['76mintgrün'02]

Jeff's suggestion to set the timing at idle is based on the new curve.  The rebuilt distributors I've spun on the Sun did not start giving more advance until around 1900 rpm, so it isn't necessary to get the idle just right to set the timing.

 

On old worn distributors the timing can vary a lot with changes in idle speed, so there are better ways to set the timing.

 

You can go back and forth between adjusting timing and the idle speed, but you're right about the sequence being 'timing first and then fuel' when it comes to adjusting the idle mixture screw.

 

Did Jeff give you any advice about which vacuum source to use?

 

Manifold vacuum will add an additional 12 degrees or so at idle, whereas ported won't add any.  So, M-vacuum works better with long-curve distributors and P-vacuum with short ones.  Here's a current discussion on that topic -- https://www.bmw2002faq.com/forums/topic/335822-weber-3236-vacuum-advance-question

 

 

I'm guessing Jeff expects you to use ported vacuum, since manifold vacuum will bump your 12-15 degrees up to 24-27 degrees at idle.

 

Set the light to 12 degrees of advance and rotate the distributor with the engine idling so that the OT line on the flywheel aligns with the driver's side of the oval viewing hole.  

 

The BB is at 25 degrees before TDC (OT line) so you can do a little simple math to use it for total advance measurements.  If you left the light set at 12 degrees and spun the engine up to where the distributor was all-in and saw the BB in the window, you'd have 37 degrees of total advance.  If it's not in the window, bump the timing light up and down until it is and then add that number to 25 for your total.  I find that easier than bumping the light up thirty-whatever degrees to look for the OT line.

 

Steven is correct about the importance of having the rotor pointing to the same place on the body when swapping distributors.  As long as that's the same as it was, you can rotate the distributor body to any position (or swap to a different distributor).  There's no need to go through the #1 at TDC as long as it was done right to begin with.

 

Tom

Edited April 10 by '76mintgrün'02

[John76]

Larry,

If your '75 has all the smog stuff (except the Weber and the 1600 engine transplant) then it is identical to a '76 California car.

Your "old" 231-176-059 distributor has both vacuum advance and retard pods, If the Black electro-valve, EGR relay and the T2 coolant switch (underside of the intake manifold) are still on your car and plumbed, the vacuum advance will be turned OFF when the engine reaches normal operating temperature. The vacuum retard will be activated.

Check to see what kind of vacuum pod is on "new rebuilt" 231-181-011 dizzy. 

Ideal spark setting is to have about 3-4 degrees static advance for starting, then add 10 degrees of vacuum advance at idle (total 13-14 degrees BTDC). This can be achieved only if the advance pod is connected to manifold vacuum.

 

21 hours ago, larry_in_socal said:

the instructions from AD, .. “12-15deg BTDC @ idle w/o Vac”

This sounds correct for a vacuum RETARD distributor.

['76mintgrün'02]

From a 2009 FAQ post

 

0 231 181 011 Bosch

It is a good number for an original BMW 2002 distributor, but was used only for one month of production, and was discontinued long ago.

 

So it was used on a standard 2002 only November 1974, then Bosch's catalog says "Superseded by 0 231 176 059" which is now noted as "Article to be discontinued."

 

 

[larry_in_socal]

Tom,

no Jeff didn't tell me which port to use, I assumed that it would be manifold port. I was told to set at idle between 12 and 15 degrees and there would be no need to time to the BB, he said that is not needed.

 

John76, I have all of the smog stuff disconnected, I have a straight vacuum line from manifold to distributor as shown below:

 

Port at manifold with vacuum line going to distributor.

 

Line from above port going to old distributor.

\

 

Picture of new distributor with retard port blocked off, vacuum port used.

 

 

I'm going to only use the vacuum port and not the retard port. That was probably used when all the smog stuff was hooked up to regulate spark and keep emissions low, but that is no longer needed, and I will use only the vacuum port.

 

So here is the plan:  with the car at operating temp...find TDC, drop in distributor, start engine, set the Innova Timing at 12 deg, slowly move distributor to see the TO at the straight mark on flywheel peek hole, tighten distributor. Plug in vacuum line as shown above, and this should be all that I need to do. The instructions were to set the distributor in and time at 12-15deg, at idle with vacuum disconnected. I was told no need to time to the BB.

So I would assume that once the vacuum is connected, the mechanical weights and vacuum port would work in sync and basically would do their "magic" and operate the car based on the curve set by the rebuilder. Since the car is starting and idling on its own, I don't think that there would be much tweaking to get to the final idle speed, as I think I'm already in the "idle speed ballpark" so to speak.

 

My plan is to get this in the car by the weekend, and I'll keep you posted on the outcome.

 

larry_in_socal

Edited April 10 by larry_in_socal

[Mark92131]

9 minutes ago, larry_in_socal said:

Port at manifold with vacuum line going to distributor.

 

Everything you are planning seems correct, but if that connection on the carb is above the throttle plates, it is ported vacuum, which is what you need for your setup (no vacuum at idle).  If it is below the throttle plates, it should be manifold vacuum.  If you were using manifold vacuum, (below the carb throttle plates or a vacuum connection directly on the manifold), then you would need a smaller static idle timing setting without vacuum (3-4 degrees) and then connect the manifold vacuum to bring your idle advance to 12ish degrees total.

 

Easy to check, set your 12 degrees of timing at idle with the line capped at the carb and disconnected from the distributor, then reattach the vacuum line at the carb and distributor and measure the advance at idle.  If ported vacuum, it should be still at 12 degrees, if manifold vacuum, it should be higher.

 

Mark92131

['76mintgrün'02]

There's really no need to mess with getting it to TDC to swap distributors.  Just use a piece of tape or sharpie to mark the top edge of the distributor body where it aligns with the rotor tip.  Then put a piece of tape on the new distributor in the same place and align the rotor there when it's installed.  You can clock the distributor wherever you want as long as the rotor and body relationship stay the same.

 

I thought it'd be cool to clock mine so the advance pod was on the carburetor side, but then learned that that orientation puts the points back where they're hard to adjust, so I spun it back around, putting the pod on the exhaust side.  I also like it when the distributor number faces forward.

 

You'll need to align the rotor around ten degrees counter clockwise from where you want it to land, due to the skewed gear spinning it as it drops in.

 

If you pull that vacuum line off with the engine running at idle and it's sucking like crazy, that's manifold vacuum.  Ported vacuum will not be sucking at all while idling, except while it is warming up and it's idling higher than normal.

 

Manifold vacuum would have been my preference with the original curve, but with Jeff's you'll need to use ported.  Otherwise you'll have too much advance at idle.  

 

The problem I had using ported vacuum was that I was getting pinging between 2-3K rpm when I gave it gas while under load.  So, listen carefully while out on your test drives.

Tom

[larry_in_socal]

After reading some of the replies, it got me thinking, what port do I have the distributor hooked up on. so I took a picture of the carb really good and here is what I found:

 

 

I only have one vacuum port on the carb, as shown above, the other port is actually on the manifold, and while I was checking this out tonight, I discovered that the rubber plug on the manifold port has a crack in it, so that will definitely be replaced, I have a vacuum gauge and I will be checking to see if the port that I currently have the distributor hooked up to is a ported "port" but I will look into it when I start wrenching on this in a few days... these are the only two ports that I see on or near the carb, one on the carb and one on the manifold as shown. I'm sure glad that I checked this out else I may have missed the cracked plug. This carb only has one vacuum port, and without testing it I really don't know if it is "ported" or "non-ported" I'll need to figure that out.

 

larry_in_socal

['76mintgrün'02]

They only put one on the carb in that location and that is the ported vacuum nipple.

 

This is a great example of why it's so helpful to post photos!  I've also discovered things when sharing photos on the site.

 

Post some more!   

Tom