Timing with Electronic Ignition, How many degrees before TDC? Options

[Ken6432]

I have a '74 914 with dual Weber 44s and a Pertronix Ignitor distributor, with no vacuum advance on it (or mechanical as far as I can tell). Pertronix says that there is no dwell setting for their distributors. They said I would be fine using a static timing technique, but I would be more comfortable using a timing light.

My question is, how many degrees before TDC to I set the timing? Or, am I missing something? It seems I need to know this in order to set the timing correctly.

Thanks for the help.

Ken

[mskala]

I have a '74 914 with dual Weber 44s and a Pertronix Ignitor distributor, with no vacuum advance on it (or mechanical as far as I can tell). Pertronix says that there is no dwell setting for their distributors. They said I would be fine using a static timing technique, but I would be more comfortable using a timing light.

My question is, how many degrees before TDC to I set the timing? Or, am I missing something? It seems I need to know this in order to set the timing correctly.

Thanks for the help.

Ken

The Pertronix Igniter is only an electronic version of the points. It changes nothing
about the ignition system other than 1) points are gone and will not need adjustment
due to wear, and 2) dwell is no longer important, do not bother measuring.

Other than that, follow the same procedure you always have. It's been a long time
since I owned a -4, but on 1.7 and 2.0 you are supposed to check for a 27 degrees
advance at 3500 RPM with vacuum disconnected, which is usually done with the
mark on the fan. If marks are missing or not known to be the right ones, you can
use the TDC mark and a timing light with programmable advance.

If your distributor is not stock, as your message implies, then also it may or may
not have the correct advance curve. Checking that would be something for the
professionals, though.

[Java2570]

(IMG:style_emoticons/default/agree.gif) 27 BTDC @ 3500 rpm. As far as I know, you can't static time Pertronix
like you can with points....maybe they just meant you could eyeball it to get it
running before using a timing light. I always thought that these Pertronix distributor
setups were more for Type 1 engines and the advance curves wouldn't be the best
for Type 4's. It's probably a lot like a 009 dizzy so you'll likely have to play around to get a good driveablity with it. Anyway.... (IMG:style_emoticons/default/welcome.png)

[Cap'n Krusty]

If it's like an 009, you're gonna have about 17 degrees of total advance, meaning your static timing is gonna be around 12 degrees BTDC, meaning you're gonna have to adjust the idle down from where it wants to be running that much advance. The high idle speed may cause the distributor to begin advancing on its own, causing further problems. See what "upgrades" not well thought out can get you?

The Cap'n

[SLITS]

Get a 1.8L dizzy and maybe have it re-curved.

Static timing is for getting the engine to start. Then the timing is set to the correct value with a light.

Mechanical advance is built into most all distributors and consists of weights and springs that you can't see until you remove the breaker plate. You will have mechanical even if it's an 009. Vacuum advance is for emissions and fuel mileage.

[Dave_Darling]

There pretty much has to be some sort of mechanical advance. If not, the car would be very sluggish at higher revs.

There has to be some point when the advance is "all in". Find that point. Hook up your timing light, and look at the fan. Rev the motor and watch the fan under the timing light, when it stops moving with higher revs the centrifugal advance is all in.

Set that to be "about" 30 degrees BTDC. The stock D-jet (1.7, 2.0) setting was 27 deg BTDC, while I think the L-jet 1.8 was more like 30+ at high revs. You will probably have to experiment to find the best setting for your particular setup.

--DD

[stugray]

I agree with Daves 30 degrees.

I set mine at 34 degees because I am at high altitude and thats what the race types in this area suggest.
I havent driven it long enough to know if I have a heat issue yet.
If I am running hot, I will back it off.

And use a variable timing light and screw the stupid timing marks on the fan.
Push the rear engine tin up about 1/4 inch and it will pop back.
Then you can see the zero degree mark on the flywheel.
It is MUCH easier to time that way than trying to see down the hole to the marks on the fan (if you even HAVE a zero degree mark on the fan).

[Ken6432]

Thanks everyone for you help. I think I got it timed pretty close and I will adjust it from here.

Ken