123 Install Today - GETTING CLOSER..., PROGRESS: BAD MPS Options

[FlacaProductions]

74 2.0 D-Jet

Heading to the garage now to start the install and my main, unresolved-in-my-brain question is if i need to hook up the vacuum line that is on my current stock distributor, on the 123.

[87m491]

74 2.0 D-Jet

Heading to the garage now to start the install and my main, unresolved-in-my-brain question is if i need to hook up the vacuum line that is on my current stock distributor, on the 123.

I'd think so if you ordered Porsche-4-R-V which is designed for a vacuum connection.

[rjames]

74 2.0 D-Jet

Heading to the garage now to start the install and my main, unresolved-in-my-brain question is if I need to hook up the vacuum line that is on my current stock distributor, on the 123.

Depends on what setting (or program if bluetooth) you're using on the distributor and what vacuum line you're talking about- retard or advance. In the distributor documentation, 'degrees negative vacuum' means to use the vacuum retard off the throttle body.
If you decide not to use vacuum with the distributor, make sure to plug the port on the throttle body. Do not plug the port on the distributor if you're not going to use vacuum.

I'm using setting 'B' so I've connected the retard vacuum line from the throttle body to the distributor. My throttle body does not have the advance vacuum port, but if it did I would plug it since it's not being used.
If I had used setting '2' I would've needed to connect an advance line off of the throttle body and plugged the throttle body's retard port.

[914_teener]

Why wouldn't you want to use it?

[FlacaProductions]

Ok. Will use the vac line from the throttle body to the distributor as it currently is. My throttle body does have an advance vacuum port is and has been plugged.

[emerygt350]

Ok. Will use the vac line from the throttle body to the distributor as it currently is. My throttle body does have an advance vacuum port is and has been plugged.

Be sure it's ported if in fact you set it for advance. I tried both retard and advance on mine since my TB has both ports. Both had interesting applications.

[technicalninja]

I'd hook that pup up to MANIFOLD vacuum only.
On my 123 distributor I'm sure the vacuum port leads to a MAP sensor.
Manifold Absolute Pressure...

Lots of stuff from the early 70s often had two "types" of vacuum.
Manifold and "ported".
Manifold is self-explanatory but ported is where it gets strange.

Posted vacuum comes from a vacuum port that is covered by the throttle blade at idle.
As you open the throttle the vacuum reading will increase sharply and tend to hold vacuum throughout most of the RPM range.
It's creating vacuum by the passage of air. The faster the air is passing the higher the value.

A little bit like blowing across a coke bottle. That weird noise is caused by differing vacuum at the entrance...

This was used MOSTLY for emission control as the old-school method of manifold vacuum to advance diaphragm would cause early burning of the fuel mixture in the combustion cycle and they were trying to INCREASE un-burned HC to the cat for early light off. The airpump was usually part of this operation to also increase O2 content.

They wanted FIRE in the exhaust manifold, and this proved to be the wrong way to go in the long run...

Hook that up to manifold vacuum ONLY. It has adjustable maps based off of this and you will drive yourself BAT-SHIT crazy trying to make adjustments if your running ported vacuum to it...

Hope this helps!

Where this gets really weird is at high RPM. Manifold vacuum is near ambient (high KPH 95 or better) and ported vacuum is pulling 20" (low KPH 30 or lower).

[DRPHIL914]

"Posted vacuum comes from a vacuum port that is covered by the throttle blade at idle.
As you open the throttle the vacuum reading will increase sharply and tend to hold vacuum throughout most of the RPM range.
It's creating vacuum by the passage of air. The faster the air is passing the higher the value."

i found that it just runs better with out using it even though i have thed-jet with vac unit. . my idle is better - been a while but i thing that i had too slow of idle with it hooked up , and i tried it every way, but dont use and and am using the curve that is ment for no vac, i think its "B" but i dont remember off the top of my head

[Lockwodo]

I'd hook that pup up to MANIFOLD vacuum only.
On my 123 distributor I'm sure the vacuum port leads to a MAP sensor.
Manifold Absolute Pressure...

Lots of stuff from the early 70s often had two "types" of vacuum.
Manifold and "ported".
Manifold is self-explanatory but ported is where it gets strange.

Posted vacuum comes from a vacuum port that is covered by the throttle blade at idle.
As you open the throttle the vacuum reading will increase sharply and tend to hold vacuum throughout most of the RPM range.
It's creating vacuum by the passage of air. The faster the air is passing the higher the value.

A little bit like blowing across a coke bottle. That weird noise is caused by differing vacuum at the entrance...

This was used MOSTLY for emission control as the old-school method of manifold vacuum to advance diaphragm would cause early burning of the fuel mixture in the combustion cycle and they were trying to INCREASE un-burned HC to the cat for early light off. The airpump was usually part of this operation to also increase O2 content.

They wanted FIRE in the exhaust manifold, and this proved to be the wrong way to go in the long run...

Hook that up to manifold vacuum ONLY. It has adjustable maps based off of this and you will drive yourself BAT-SHIT crazy trying to make adjustments if your running ported vacuum to it...

Hope this helps!

Where this gets really weird is at high RPM. Manifold vacuum is near ambient (high KPH 95 or better) and ported vacuum is pulling 20" (low KPH 30 or lower).

On my '74 2.0 with 123 ignition, I've connected the disty to manifold (not ported) vacuum. But I've not been able to program a MAP curve into the 123 that works well (provides extra advance just when the engine is under load). If anyone has successfully done this, could you share the MAP curve set points you're using?

Gotta say though, car seems to run just fine without the vacuum line attached to the disty.

[FlacaProductions]

ok - it's in, got a green light, put the cap and wires on buttoned things up and had to call it a day.

Will start it, synchronize with the app and load in a curve tomorrow. Currently the vacuum is connected and we'll see how it goes from there. Will update tomorrow.

Big thanks - multiple, quick responses are really appreciated. this place is the best.

[technicalninja]

On my '74 2.0 with 123 ignition, I've connected the disty to manifold (not ported) vacuum. But I've not been able to program a MAP curve into the 123 that works well (provides extra advance just when the engine is under load). If anyone has successfully done this, could you share the MAP curve set points you're using?

Gotta say though, car seems to run just fine without the vacuum line attached to the disty.

And this is where it is counter-intuitive...

Distributor advance is MOSTLY a function of RPM. As the engine speed increases we need to "start the fire" earlier to achieve MBT (mean best torque-highest cylinder pressure) about 10 degrees AFTER top dead center. At a specific RPM advancing further is fruitless as the time available to complete the burn becomes too short.

So mechanical advance usually starts just off of idle (800-1200 rpm) and is "All In" by 3K-4K. This IS the reason that 914 balancers are marked at 37 degrees. You are setting "total" timing by hunting the 37 degrees mark at 3K RPM.

Load is also a factor with timing, but it is the OPPOSITE of RPM. As load goes UP timing should move down...

A timing curve that will make any gasoline-based engine function is as follows.

Mechanical advance 25 degrees total at 3.5K rpm.

Initial timing 10 degrees (I call this static timing) this is what will show with both the mechanical and the vacuum advance disabled. This is where MOST adjustable timing vehicles are timed with a light.

Vacuum advance 10-15 degrees at 17-20" of vacuum.

At idle this set up will show initial + vacuum and give you a sum of 20-25 degrees.
The engine will idle fine with just 10 (no vacuum) but if you add the vacuum, you will notice the engine is idling 400 rpm higher and is more stable requiring a reduction of both air and fuel to idle at the same rpm as the 10 degree set up.

At 4000 rpm WOT you will be at Initial+ Mechanical or a sum of 35 degrees and this works fine.

But at 4k rpm CRUISE you will have initial, mechanical, and vacuum (throttle blades will be at a low percentage and manifold vacuum will be high) for a sum of 45-50.

This "strangling" of the engine via the throttle blades produces an incomplete fill of the cylinder and is harder/slower to burn requiring additional timing to achieve MBT at 10 degrees ATDC.

So, timing goes up with RPM and reduction of load...

A race car that is ON throttle most of the time does not need vacuum advance. This is why a lot of you say "works fine without vacuum" because it does, especially when the throttle is hammered which is how most folks "test" their performance.


A member on here (I think it was emerygt350) did some testing with a good cylinder head temp gauge and posted some very interesting data IMO.

When he added vacuum advance his head temps dropped dramatically!

Running too little advance means some of the charge has not be consumed in the cylinder and the burn continues into the exhaust system. This is HARD on head temps IMO and his testing showed how very easy it is to achieve cylinder head damaging temperatures.

Correct timing fixed his shit up fine...

To me his data ment...
Oh my god! an accurate cylinder head temp gauge is an ABSOLUTE must for tuning.
Be damn careful with the timing on these, even stock ones can suffer catastrophic destruction (over 425 temps) easily.

Running a vacuum-based timing curve will improve cruise to WOT acceleration, fuel economy, and keep cylinder head temperatures at bay. It will make idle more stable and (if you're a greenie!) it should reduce emissions...


Of note : Pretty much ALL ported vacuum is gone now. I cannot remember a modern car that uses ported vacuum for anything at all.

[FlacaProductions]

Had a little moment tonight and went back out and attempted to start. No joy. Fuel pump runs as normal, cranks fine but doesn't even act like it wants to catch. Rotated distributor slowly with no luck.

Plug wires are on in correct order.

New 123 coil installed as well. Large(ish) black wire to + and black/purple tach wire to - on the coil (as usual/before).

Red from 123 to + black to - blue to ground.

Yellow from 123 into left distributor connection/white into right - middle is open. (as looking into connector with "high point" of the female connector on top)

I get bluetooth connection to app.

Not sure what I don't have right but I'll maybe go back to green light setup point and double check that.

[FlacaProductions]

Still no luck.
I’ve basically redone the install.
My only real observation is that plug one location is now 180 from where it was before the 123. It’s now at 4 o’clock where it was at 10.

Plug wires in same correct order and I get a green light when setting up the 123 but the number 1 location is the only thing that looks odd. But according to the instructions, this is not out of the ordinary.

I’m stuck.

[914_teener]

Call them....you've done something wrong if it was running before.

MAKE SURE....you've hooked up everything correctly.

Check that you are getting 12v to the coil.


Run the VAC advance from ported vacuum (that's the atmosphere side) of the TB.

Set the static timing first...from the spec. Your idle should be around 600-800 RPM's with the stock cam.

The VE on a stock engine is optimized to the spec curve...you can't gain anything by changing it...unless it's not stock.

[FlacaProductions]

I did call and Ed was great. Confirmed all the wiring. The only thing I haven’t tried is a 12v line straight from the battery to the coil but I get 12v at the coil already and also just tried the old coil for fun.

Still no joy.
I’ve removed and done the whole thing over multiple times. It sputters. A little. Never fires. I rotate in small bumps each way. Neither seems better than the other.

I’m lost.

More:
just talked to Ed again and he said short of running a hot line straight from the battery to the + side of the coil to eliminate any resistance issues, I'm going to send it back let Ed see if it's just a bad unit. Stuff just doesn't arrive DOA much anymore but I guess I hope it is.

I've basically spun that distributor nearly 270 from its starting point and at no point does it act like it's close to starting. I've actually gotten some nasty kick-backs that don't excite me much as I hate fixing one thing only to create another issue.

I've confirmed spark by pulling the coil wire and holding it close to a ground point - i can hear the fuel pump run at key-on. I've confirmed over and over the firing order and plug wire order.

shrugs. I'm sure I'll get it but man...it's a head-scratcher right now.

[Rob-O]

The whole TDC is now 180 off is a red flag. Either the distributor was 180 before but the wires were rerouted so the firing order was correct…or the distributor is now 180 degrees off. If the plug wires didn’t change when the distributor position did it won’t run. When you look in the cavity that the distributor sits, the dizzy drive gear that the distributor fits in looks symmetrical but is not. So, just to get it all correct set TDC using the flywheel, then make sure the distributor drive gear is positioned correctly (you can easily find pics online). Then install the distributor (again, the ‘key’ and gear are offset to one side so if the distributor isn’t engaging check that the key on the dizzy is positioned correctly to engage the dizzy drive gear in the engine). Wire up the dizzy, install plug wires to correct cylinders. Car should start. Then you can adjust advance via the app (if you have Bluetooth version) or choose your program if you have the old type 123.

[FlacaProductions]

Yeah @Rob-O - it's 180 "out" and my head is so messed up right now.

Plug wires are in the same order - just now, #1 is at 4 o'clock where it used to be at 10.

Is it as simple or am I going to hurt anything by rotating every plug wire by two spots and get them back where they started - even tho when set to TDC (off the white mark on the fan - not the red mark) the rotor points to 4 o'clock (which is where I have #1 wire)

and I know what you're talking about with the key - threw me off a bit on the initial install as the distributor wasn't sitting all the way down. Rotated the whole unit and felt it go in and that's where we are now. I'll check for pictures of the distributor drive gear now...

[Front yard mechanic]

I’m no expert on the 123 but icarr on the pelican site is. The install I did recently I remember a few things 1 bring engine to tdc with the old distributor 2 mark the rotor location should be at #1. 3 install the new distributor and hookup the wires but not the black. Go to your Bluetooth on your phone and open the app & turn power on and turn till the light comes on. the location of the rotor is your new #1 the follow firing order based on rotation. Now the last thing is hookup the black wire. Fingers crossed and fire it up. The position of the distributor on install doesn’t matter just locate it where you like for easy / clean install

[FlacaProductions]

RESOLVED.
IT WAS 180 OUT.
I didn't think you could actually get the distributer to seat all the way down if it was 180 out - due to the offset key.
Boy was I wrong. I guess.
Your post @Rob-O got me thinking and after I thought i was done for the day, went back out, pulled the distributor, looked at the key which appeared to be correct after finding a pic in the Haynes manual, spun the distributor shaft 180 and it dropped right in!

Did the green light orientation, hooked up the black wire to the coil, key on, remote button and it started right up. First try.

Now the morning should be quick work of dialing it in and then some fine tuning.

I KNEW it had to be me but there just wasn't enough wiring to screw up. The indexing of the distributor was the one thing I kept repeating incorrectly since I thought it would only fit the "right" way and wouldn't seat all the way down if it were anywhere but correct.

Wow.
Thanks for ALL the input from the best board in the world.
And to be clear - it's NOT a 123 issue - and Ed was great fielding two of my calls today and setting up my returning it to have it checked out.

All's well that ends....I just hope I didn’t hurt anything. Had a couple nasty backfires and bucks along the way…

[porschetub]

RESOLVED.
IT WAS 180 OUT.
I didn't think you could actually get the distributer to seat all the way down if it was 180 out - due to the offset key.
Boy was I wrong. I guess.
Your post @Rob-O got me thinking and after I thought i was done for the day, went back out, pulled the distributor, looked at the key which appeared to be correct after finding a pic in the Haynes manual, spun the distributor shaft 180 and it dropped right in!

Did the green light orientation, hooked up the black wire to the coil, key on, remote button and it started right up. First try.

Now the morning should be quick work of dialing it in and then some fine tuning.

I KNEW it had to be me but there just wasn't enough wiring to screw up. The indexing of the distributor was the one thing I kept repeating incorrectly since I thought it would only fit the "right" way and wouldn't seat all the way down if it were anywhere but correct.

Wow.
Thanks for ALL the input from the best board in the world.
And to be clear - it's NOT a 123 issue - and Ed was great fielding two of my calls today and setting up my returning it to have it checked out.

All's well that ends....

Don't beat yourself up on this ,many on here have done the same with a stock systems
,good result hope you get it dialed in 100% , (IMG:style_emoticons/default/beer.gif)