HELP: Getting it going. Timing, Weber DCOE

[2002Scoob]

Because I'll eventually also be marching down this road with timing and tuning (once a settlement is reached with my hack-job mechanic), I've been paying attention to this thread.

 

the OP mentioned painting the OT line white on the flywheel, but elsewhere I see people recommending painting the BB thats pressed into the flywheel edge to do timing. Given those two things are a few degrees off, would that affect the OP's timing reading?

 

I'm learning here too

[Simeon]

25 degrees off to be exact (25 deg btdc). BMW chose this as a common point on all of their various distributor curves for given engine speed.  If the distributor has a different part number then the rest of the curve is likely to be different.  You could, however, guarantee that at either 1400 or 2400 (depending upon whether the car was carbed or injected) the car would be correctly timed at the ball. 

[2002Scoob]

11 minutes ago, Simeon said:

25 degrees off to be exact (25 deg btdc). BMW chose this as a common point on all of their various distributor curves for given engine speed.  If the distributor has a different part number then the rest of the curve is likely to be different.  You could, however, guarantee that at either 1400 or 2400 (depending upon whether the car was carbed or injected) the car would be correctly timed at the ball. 

So, in that respect, if you were to time off the ball, you'd actually want to just add an additional 7-9 degrees advance to reach the intended 32-34 at 3k rpm? Sorry to Hijack, OP!

 

You're free to just tell me to go back to google and YouTube and keep watching tutorials

Edited October 6, 2016 by 2002Scoob

[MildSeven]

1 hour ago, 2002Scoob said:

Because I'll eventually also be marching down this road with timing and tuning (once a settlement is reached with my hack-job mechanic), I've been paying attention to this thread.

 

the OP mentioned painting the OT line white on the flywheel, but elsewhere I see people recommending painting the BB thats pressed into the flywheel edge to do timing. Given those two things are a few degrees off, would that affect the OP's timing reading?

 

I'm learning here too

 

I pained both, the ball and the TDC (still very hard to see), given the angle and where I'd need to stick my light/head.

 

I assume the BB would work with a standard timing light, so you wouldn't need the advance function, simply time off the ball. I bought a timing light which has the advance function I'm going off TDC and using the advance function.

 

...at least that's my assumption from what I've learnt on here.

 

I'll be following around in the garage tomorrow, checking the crane optical light and the other suggestions you guys gave me.

 

PS: I've ordered a new rotor/ distributor cap (and since it wasn't much, that clear cap as well)... and some wires.

I've also been mulling over some Spanish 45DCOEs. since finding a match seems like it might be difficult.

 

Edited October 6, 2016 by MildSeven
PS:

[TobyB]

I dunno.  I have one Spanish DCOE and one Spanish rowboat anchor. 

The thing's just machined completely wrong.  (one main jet's 4mm lower than the other)

 

I don't think you should give up on yours just yet.

 

t

 

[Simeon]

3 hours ago, TobyB said:

 

I don't think you should give up on yours just yet.

 

t

 

 

You did say that these carbs had been running well in the past. If someone else can do it, so can you. 

[Chris_B]

Your progression holes are hugely different. Unless you are a racer and are going to drive this car only at WOT, this is problem. Under normal street driving, the transition circuit will control your mixture until the main jet kicks in (although the idle circuit also has a significant impact on mixture during transition). The ideal thing to do would be to pick up another DCOE 9 carb (perhaps not a very practical suggestion). You may be able to find a machinist who could drill out the transition weill and install a brass plug with correctly positioned holes.

[MildSeven]

I received and installed;

- new distributor cap (+ the clear distributor cap to test the spark)

- new rotor

- new spark plug wires.

 

So I'm a little fed up with this whole timing/tuning debacle... and I spent most of the time this weekend installing the hood and my aspx a/f gauge stopped working too, I tried re calibrating, so now I'm waiting for a reply from tech support.

 

 

Here are my new questions/headaches

 

- When I start the motor, it's revs super low. like 300rpm or something, so I adjust the idle screw higher to keep it from dying... but then once the engine warms up a little. The engine speed shoots up to like 2,000-2,500. :s

What causes this behavior?

 

- After receiving the clear distributor I popped it on and hooked up the timing light to plug #2, then I shinned the light on #2 distributor plug. The purpose of this is to see if the optical reader is aligned properly.

Most of the time it looks like it's pointing at #4 (maybe #1, but definitely to an adjacent spark), unless I rev the motor higher, when "rev'ing it" it looks properly aligned on #2.

I don't get how the light would shine when the rotor isn't pointing at #2 because I thought the rotor controlled the light. so my question is, what was I on?

 

 

my garage does smell very rich when the cars running.

 

 

 

 

[TobyB]

Wow.  That sounds like the internal timing in the distributor's way off- if you run it in the dark, is there a lightning storm inside your cap???

 

After all of this,  I'd almost recommend spending the $100 on a Pertronix, just to rule out the Crane box.

 

As to the idle, that sounds like one of a few things- an air leak, a leaky choke (s) (really a variant on air leak, but could be a fuel leak)

or something messed up with the mechanical advance in the distributor.  Or the above Crane trouble, I guess.

 

I once had a Volvo 142 (parts car for the 122, go figure) that had very loose, sloppy springs in the distributor.

On the choke, it would warm up at 1500.  But then it'd idle at 500 warm.  But THEN, if you tried bumping the twin SU's up to, say, 800,

it would shoot to 2k or more.  Watching the timing light explained this one- at about 700, the mechanical advance would kick in

rapidly, and the advanced timing would run the idle revs up.

 

fwiw,

 

t

 

[MildSeven]

30 minutes ago, TobyB said:

Wow.  That sounds like the internal timing in the distributor's way off- if you run it in the dark, is there a lightning storm inside your cap???

 

After all of this,  I'd almost recommend spending the $100 on a Pertronix, just to rule out the Crane box.

 

As to the idle, that sounds like one of a few things- an air leak, a leaky choke (s) (really a variant on air leak, but could be a fuel leak)

or something messed up with the mechanical advance in the distributor.  Or the above Crane trouble, I guess.

 

I once had a Volvo 142 (parts car for the 122, go figure) that had very loose, sloppy springs in the distributor.

On the choke, it would warm up at 1500.  But then it'd idle at 500 warm.  But THEN, if you tried bumping the twin SU's up to, say, 800,

it would shoot to 2k or more.  Watching the timing light explained this one- at about 700, the mechanical advance would kick in

rapidly, and the advanced timing would run the idle revs up.

 

fwiw,

 

t

 

 

Toby, thanks for answering!

 

Engine idle speed... I have noticed some fuel around the choke cover (cold start unit) which I replaced with a block off plate. I keep reading things on google about vacuum leaks, but on my setup I think the only place I could have a leak would be on the manifold, carbs themselves, or brake booster hose/booster, am I correct in assuming that?

 

 

[Hans]

On the idle front, you could check the distributor to make sure the advance weights are free, springs in place , etc. I think a timing light would show an erratic distributor. 

[TobyB]

If you're running the vibration isolation mounts, they can leak.  And they can leak dynamically-

as in, if they're loose, have loose o- rings, a split, whatever, at certain revs they can open up.

 

Me and my propane torch found that one afternoon when I was just frustrated

silly as to why the race car had a flat spot at a particular rev range but only when I was part throttle.

Tightened the mounts a bit, solved the problem.

 

Does your block off plate hold the warmup plungers down?   The stock linkage

does, and they need to be seated down to keep them from bouncing around.

Personally, I have never used the warmup circuit, but it's a neat feature...

I've always left the lever assembly intact, and jus made sure that the levers stayed in the closed position.

 

hth

 

t

 

[Hans]

Good suggestions from Toby. Those O ring mounts are a pain if not torqued evenly (good luck with the lower nuts) and mine all split after a few years. I also wired the cold start levers shut.

[MildSeven]

thanks guys. gonna do some more checks on the weekend, including bench testing the O2 sensor, re-checking the phasing of the crane/distributor with timing light, and checking blot torque on the carbs to intake manifold (anti-vib mounts).

 

The block off plate is a flat plate which simply covers the opening and I have seen some very slight wetness around it.

Edited October 19, 2016 by MildSeven

[TobyB]

Whoah, wait- 

 

the 'warmup' circuit on a DCOE has a plunger per bore, and the plungers are basically poppet throttles.

Those throttles are usually positively held down by the 'warmup' (choke, although it's NOT a choke)

lever, and there are springs in the works.

I THINK the springs are above the plungers. But the plungers often stick, leak, etc, and this makes tuning a real pain in the kiester.

 

Ya gotta make sure they're sealing.  And the block off plate thing scares me.  Because it means the plungers are no longer

being positively held down, just hoping that the springs are doing their best.

 

http://www.rx7club.com/1st-generation-specific-1979-1985-18/45-dcoe-info-references-882842/

has some pix robbed from the Weber manual I can't find right now.

 

It's (54- plunger) and (55-spring) in the below diagram.

 

hth

 

t