Timing 1973 2002A **Help Please**

[20db02]

Hello friends,

 

I’m looking for some technical support in timing a 2002A. The car runs well through most of its spectrum, but it's running a tad rich and occasionally stalls at idle. I don’t want to adjust the carburetor until I've verified the timing is correct. I’m getting conflicting information from the Haynes manual, which doesn’t mention the case of having a mechanical advance. Any help would be greatly appreciated.

 

Thank you all.

 

[TobyB]

Technically, I advise you to time to the ball using an inductive timing light, 

and whether you do it at 1400 or a different rpm depends on which distributor you have.

Which is determined originally by year of manufacture, but 50 years later,

is determined by the history of the car, and chaos.  And entropy.

 

And by what runs well.  Because almost all of these things are well past worn out by now.

 

All 2002s have a mechanical advance.  Not all 2002s have a working mechanical advance...

 

Most  2002s also have a vacuum advance.

 

Some 2002s have a vacuum retard.

 

A few have both advance and retard.

 

Some subset of the above have working vacuum pods.

 

But that doesn't much matter, as standard timing procedure is to disconnect the vacuum, time the car

at a set RPM, and off you go.

 

t

[20db02]

2 minutes ago, TobyB said:

Technically, I advise you to time to the ball using an inductive timing light, 

and whether you do it at 1400 or a different rpm depends on which distributor you have.

Which is determined originally by year of manufacture, but 50 years later,

is determined by the history of the car, and chaos.  And entropy.

 

And by what runs well.  Because almost all of these things are well past worn out by now.

 

All 2002s have a mechanical advance.  Not all 2002s have a working mechanical advance...

 

Most  2002s also have a vacuum advance.

 

Some 2002s have a vacuum retard.

 

A few have both advance and retard.

 

Some subset of the above have working vacuum pods.

 

But that doesn't much matter, as standard timing procedure is to disconnect the vacuum, time the car

at a set RPM, and off you go.

 

t

Thank you Toby, I should have clarified the distributor is vaccumless. No advance, no retard. The car is very original with low miles (very good receipt history) but still, a lot can happen in 50 years for sure. Thanks for the “dizzy”ing advice! Hah! 
 

[Mark92131]

1 hour ago, 20db02 said:

Thank you Toby, I should have clarified the distributor is vaccumless.

 

If you have a mechanical distributor on your automatic, it isn't original to your car.  What year is your automatic and what are the last three numbers on the distributor body.  That will get us closer the expected timing curve for the distributor you have.

 

Mark92131

[20db02]

3 hours ago, Mark92131 said:

 

If you have a mechanical distributor on your automatic, it isn't original to your car.  What year is your automatic and what are the last three numbers on the distributor body.  That will get us closer the expected timing curve for the distributor you have.

 

Mark92131

Hey Mark, thanks for the reply. I’ve collected a few photos that may lead us in a better direction. And while doing so, was hit in the face with a giant sticker I’d never noticed with some helpful info. It may also be helpful to mention it has a header. No other engine mods that I know of. 
 

 

Edited July 23 by 20db02

[visionaut]

That’s a ti/tii replacement dizzy…

 

Depending on the year of your 2002A, your curve would be different/very different from a ti:tii advance curve.

 

(simplified dizzy curves comparison pic)

[Mark92131]

Yeah, that Tii "002" distributor won't be ideal for your automatic.  The Tii distributors don't have enough total advance for your naturally asperated motor, tops out around 26 degrees.  You should be at the "Ball" (25 degrees BTDC) at 1500 RPM and max out around 33 degrees at 2500+ RPM.

 

Mark92131

[20db02]

So, would it be best to switch back to a standard distributor? I’ve got a 73’ parts car that should have one. 

[visionaut]

Ideally, Yes - like Mark said, the Auto

wants the vacuum advance.  But only if the other dizzy isn’t worn out… Check that it’s good, and report it’s dizzy number too. 

 

As a heads up, you may/may not be able to swap over your current cap/rotor/points to the other dizzy..

 

Re-hooking up the carb vacuum is straightforward. You should have a plugged vacuum takeoff by your carb, and you’ll need a new vacuum line.
 

Swapping distributors means you’ll be fully resetting your timing  from scratch/TDC..

 

 

FWIW, I have odd suspicions your M10 might have more than just a mech-only dizzy swap and headers…  Do you know what cam/pistons are in there? 😉

 

ps: the Service Repair Manual is a useful info resource:

https://www.bmw2002faq.com/articles/technical-articles/history-and-reference/bmw-2002-service-repair-manual-r247/

 

[Mark92131]

The Emissions sticker thinks its a 1973.  Does the VIN on the motor match the VIN on the chassis?  The switching out a standard distributor for a mechanical distributor from a Tii, (002 or 008) was a popular performance modification back in the day.  Unfortunately, it didn't help the performance in a positive way.

 

If the other Distributor is still good, no slop in the rotor shaft, vacuum plate is operational, you could clean it up, buy a new set of points, condenser, cap and rotor, run it and see what maximum advance it produces.

 

If it is the original motor, matching the car's VIN, and the head is original (Should be an E12 with a casting date between 72 and 73), then stock pistons would be the 8.1:1 or 8.3:1 "grand piano" style.  If the motor had a performance rebuild with the same E12 head, it could have 9:5:1 "grand piano" style pistons.  You can buy a cheap borescope attachment for your iPhone and stick it down the spark plug hole to confirm what pistons are in there.

 

Mark92131

[20db02]

@Visionaut and @Mark92131,

 

Interesting… I’ll lean into the possibility that someone was aiming for performance and didn’t just throw the car together haphazardly. Maybe there’s more to the engine than meets the eye.   I’ll stay optimistic until I can borescope it.
 

The motor VIN matches the chassis VIN, and it is a '73.

 

The car feels like it pulls pretty well and has very linear power through its range, even with the automatic transmission. The only issue I’m noticing is that the idle isn’t super smooth. I slightly turned the idle up to eliminate the random stalling for now, but I’ll continue investigating the timing and distributor situation. 
 

I’ve studied these cars for years but have only had this one for a couple of months (most of that time spent working on upholstery), so I’m still figuring out its quirks and learning some things.

 

Thank you both! 

[20db02]

Just got back from a nice little cruise.

[gambitpaul]

On 7/23/2024 at 8:24 PM, 20db02 said:

Just got back from a nice little cruise.

Great looking interior. How do you like those door handles? Billet ones from IE, right?

[20db02]

33 minutes ago, gambitpaul said:

Great looking interior. How do you like those door handles? Billet ones from IE, right?

They are the IE door handles. I love them but I had to make a small modification. They attach the door handle post via 4 Allen screws all pressing in on the hollow door handle post. I cut a small piece of metal rod to fit inside the post to keep it from collapsing under the force of the Allen screws and having the handle come loose. 
 

I love the simplistic look of the door cards but my wife might kill my if I don’t put the arm rests back on!