L-jet ignition timing, Does retarded ignition raise oil temp? Options

[davesprinkle]

Everyone, I'm posting to inquire about your ignition timing experience. Here's the setup:

-- About 7 years ago or so, I had the 1.8 liter engine in my '74 rebuilt. Displacement is now 2056cc. I'm still running the stock L-jet system.
-- Fuel injection lines and vacuum lines have all been replaced in the last two years.
-- Wiring was rebuilt about 6 years ago. All fresh.
-- Running the stock points and distributor. Ignition timing set to factory specs (7.5 degrees BTDC at idle with vacuum line disconnected.)

Here are the symptoms: Above 50% throttle and above 3700 rpm, the engine rattles and pings, with accompanying torque fall-off and plumes of blue-white smoke. In the past few years, I've just driven around the problem, basically not going to full throttle or revving the engine.

Today, I pulled about 10 degrees of ignition timing out of the engine. (Hard to tell exactly how much, since there aren't any markings on the pulley.) (I'm about 1 1/3 fan blade away from the 7.5 degree mark. By my calculations, each blade is 7.5 degrees, so this should be about 10 degrees retarded from factory spec.)

Result: Engine now will accept full throttle to redline without complaint, rattle, or ping. Also, oil temp is about 80F higher than previous. (Previous oil temp was always very low at about 130F. Now runs at or above 210F.) Measured with a factory VDO sender and gauge.

Here's my question -- in your experience, does retarding the ignition timing lead to higher oil temperatures?

[ClayPerrine]

Did you increase the injector size when you increased the displacement? L-Jet pressure regulator can't be adjusted, so the only recourse you have is either to increase the injector size, or adjust the AFM. I recommend you get bigger injectors.

Use the ones from a 1980 Datsun/Nissan 280ZX. They are slightly larger than a 914 L-Jet injector, and will bolt right in.

Also check your advance on the distributor and make sure it is working correctly.

Clay

[jim_hoyland]

Dave” I had similar symptoms after going 2056, the 1-2-3 distributer cured all. Smoother acceleration through range of rpms, no pinging, no overheating. The only other mod I did was install the larger vanagon throttle body.
The 1-2-3 was my salvation.... (IMG:style_emoticons/default/smile.gif)

See: https://123ignition.com/product/porsche-4-r-v/

[davesprinkle]

Did you increase the injector size when you increased the displacement? L-Jet pressure regulator can't be adjusted, so the only recourse you have is either to increase the injector size, or adjust the AFM. I recommend you get bigger injectors.

Use the ones from a 1980 Datsun/Nissan 280ZX. They are slightly larger than a 914 L-Jet injector, and will bolt right in.

Also check your advance on the distributor and make sure it is working correctly.

Clay

Clay, thanks. I'm still running the factory injectors. I suppose it's possible I'm saturating the injectors under high load. Good advice. I'll check that. Also, I'll confirm the advance mechanism.

[davesprinkle]

Dave” I had similar symptoms after going 2056, the 1-2-3 distributer cured all. Smoother acceleration through range of rpms, no pinging, no overheating. The only other mod I did was install the larger vanagon throttle body.
The 1-2-3 was my salvation.... (IMG:style_emoticons/default/smile.gif)

See: https://123ignition.com/product/porsche-4-r-v/

Jim, I've been considering a 123 distribulator. Glad to hear first-hand positive experience. What ignition curve do you run?

[rbzymek]

Dave,
In general timing that is retarded from MBT (minimum spark timing for best torque or the spark timing for maximum brake torque) will generate more heat. The reason is that the maximum pressure does not occur at the optimum crank angle to extract the most work from the charge as the piston descends. Less work (torque) extracted means more heat rejected for a given fuel quantity burned. That is why old water pumpers overheated when the distributor failed in a retarded mode.

I am also running a 2056 L-Jet and had timing issues. Yes, you are supposed to set it to 7.5 Deg BTDC at 800/900 RPM (1.8L procedure). The problem is you do not know what advance your 50 year old mechanical advance distributor is providing at 3500 RPM. I recommend using the 2.0L procedure to achieve 27 Deg at 3500 RPM. If you are using the 1.8L fan, the timing mark is at 7.5 Deg BTDC. So set your timing light for 19.5 Deg and dial it in at 3500 RPM. Bingo, you have compensated for the advance mechanism in your distributor. The 1.8L distributor also has a vacuum retard hose which provides stability at idle if it is needed. It has no effect off idle.

Also make sure you are running at least 91 octane fuel. Good luck!
Ray

[rbzymek]

I agree wit Clay, use the Datsun injector. The equivalent can be purchased here:

https://www.amazon.com/Standard-Motor-Produ...r/dp/B000VB32IA

It is 188 cc/min at 2.5 Bar.

The one other critical component is the AFM (vane meter). I had a load of grief until I found a good one and dialed it in with an AFR meter.

[davesprinkle]

I agree wit Clay, use the Datsun injector. The equivalent can be purchased here:

https://www.amazon.com/Standard-Motor-Produ...r/dp/B000VB32IA

It is 188 cc/min at 2.5 Bar.

The one other critical component is the AFM (vane meter). I had a load of grief until I found a good one and dialed it in with an AFR meter.

Ray, can you elaborate on the need for different injectors? The AFM, ECU, and injectors are a matched set. And they don't care about engine displacement, only airflow. Seems that you would only need bigger injectors if your larger engine flows enough air to saturate either the AFM or the injectors.

[rbzymek]

Dave,
I went with the Datsun injectors based on Clay’s advice plus they were used on the 912 L-jet system. You are correct, the 1.8 injectors will work but the vane meter could hit the stop before the bigger motor hits maximum airflow. By using a bigger injector and putting more tension in the AFM spring you of course will increase the upper airfow capability. If it did hit the stop you would go lean which could destroy the engine. I do not have engine airflow data or an AFM calibration curve but that’s the idea behind using larger injectors.

[rbzymek]

Dave,
I would also recommend that you buy or borrow a wide band AFR meter to protect your 2056 investment. Otherwise you are flying blind. You want around 13:1 AFR in normal operation and about 12:1 during heavy acceleration. The richer mixture has an engine cooling effect through evaporation of the unburned fuel (because it is too rich to burn completely). But if you operate way rich you can wash the oil off the bores and cause scoring. If you run way lean you can burn the engine up. AEM makes a good AFR meter.

I went through three AFM's until I found one that was not defective and could be adjusted. The first was "certified rebuilt" from a familiar vendor. I wasted a lot of time because I did not suspect a "good" part.

[ClayPerrine]

Dave,
I would also recommend that you buy or borrow a wide band AFR meter to protect your 2056 investment. Otherwise you are flying blind. You want around 13:1 AFR in normal operation and about 12:1 during heavy acceleration. The richer mixture has an engine cooling effect through evaporation of the unburned fuel (because it is too rich to burn completely). But if you operate way rich you can wash the oil off the bores and cause scoring. If you run way lean you can burn the engine up. AEM makes a good AFR meter.

I went through three AFM's until I found one that was not defective and could be adjusted. The first was "certified rebuilt" from a familiar vendor. I wasted a lot of time because I did not suspect a "good" part.

(IMG:style_emoticons/default/agree.gif)

I use an LM1 to tune the injection. Just using the default settings can cause issues. The 2056 will move more air than the stock 1800, and the AFM can get pegged out.

I would also recommend the vanagon throttle body conversion. It woke up the motor in Betty's 914 when I put it in. More air in = more performance.


Clay

[jim_hoyland]

Dave,
It’s set to curve 2 or 3.
I would recommend the Blue/Tooth enabled unit. You can store 2 curves on the iPhone and select from the phone; plus, the Distributer can be disabled via Blue-Tooth.
Previously,I ran the Mallory Unilite, which was atop up from the stock units; the 1-2-3 is the next step up.

[Mark Henry]

More than a few times I've sorted engines with either way too much CR or to little, I you're building an engine you have to do the CR math. No excuses, with the CB (etc) engine calculator it's easy work.

May or may not be relevant to the OP's issue, but the engine must be mechanically sound first to have a good outcome.

[pete000]

I went with the blue toot 123 and it was a fantastic improvement on my 74 2.0

[Porschef]

Dave” I had similar symptoms after going 2056, the 1-2-3 distributer cured all. Smoother acceleration through range of rpms, no pinging, no overheating. The only other mod I did was install the larger vanagon throttle body.
The 1-2-3 was my salvation.... (IMG:style_emoticons/default/smile.gif)

See: https://123ignition.com/product/porsche-4-r-v/

I did the same thing as Jim; larger throttle body and the Einz Zwei Drei distributor.

Made all the difference, including a much improved cold start.

[djway]

I agree wit Clay, use the Datsun injector. The equivalent can be purchased here:

https://www.amazon.com/Standard-Motor-Produ...r/dp/B000VB32IA

It is 188 cc/min at 2.5 Bar.

The one other critical component is the AFM (vane meter). I had a load of grief until I found a good one and dialed it in with an AFR meter.

Stock L-Jet injectors are 190.2 cc/min
Turbo Z 190
NA Z 170
912 I believe was 200, I don't have that chart right now.
My pressure regulator runs around 38 non idle.
Are you sure the Z helps?
I start tuning my car on the road in the next day or two using afm.

[ClayPerrine]

I agree wit Clay, use the Datsun injector. The equivalent can be purchased here:

https://www.amazon.com/Standard-Motor-Produ...r/dp/B000VB32IA

It is 188 cc/min at 2.5 Bar.

The one other critical component is the AFM (vane meter). I had a load of grief until I found a good one and dialed it in with an AFR meter.

Stock L-Jet injectors are 190.2 cc/min
Turbo Z 190
NA Z 170
912 I believe was 200, I don't have that chart right now.
My pressure regulator runs around 38 non idle.
Are you sure the Z helps?
I start tuning my car on the road in the next day or two using afm.

The injector listed in PET For the 1.8 L-Jet is not the one delivered from the factory when the car was new. It has been superseded in the parts catalog by a later injector. The one for the Z car is the same as the 912E, and works better than the stock injector.

This is not hearsay on my part. This comes from years of experience.

Clay

[Porschef]

Ahh, yes, I may have left that out, I also have 912 injectors. I messed with the vane spring to allow more fuel under acceleration, and also with the static adjuster, as seen on the Itinerant Air site. It’s a fine line, having a wide band AFR meter helped tremendously, it’s pretty much a necessity. (IMG:style_emoticons/default/beerchug.gif)