Help diagnosing timing issue
 

Good morning,

Having trouble setting the timing on my 1977S. It has been swapped to a 3 liter with Weber’s prior to my ownership.

I don’t have any info on the car other than what I have learned on my own.

I found that it seemed to missing or lurching in the mid rpm range. Carbs and accelerator pump seem satisfactory. So I moved on to checking ignition system. When hooked up to the timing light the timing at idle is sitting around at about 30-32 degrees advanced and I’m not sure how the car even runs. Just guessing at the degrees from the crank pulley marks. Just purchased this timing light and it is pretty basic. Hooked up as per Bentley manual with the spark plug clamp facing the correct direction.

The plugs, wires and coil(MSD) are new and I have since installed a new green coaxial wire from Porsche to the distributor. The ignition(Perma time)cap and rotor are not new. New cap and rotor on the way. Cleaned them up and find no cracks. The rotor measures just over 5k resistance. I believe this means it is a rev limiter type? I have ordered a conventional rotor.

The distributor has a vacuum advance which isn’t hooked up but I have confirmed is functioning. The distributor does not have points.

Any help/advice on this matter would be appreciated.

Thank you Steve Mc.

Blame Canada?

For what?

It’s a reference to South Park.

For a 3.0 distributor, idle timing should be about 5 degrees BTDC
You have about 20 degrees available from the dist centrifugal advance.
The vacuum pod will give you Several degrees more advance above 25 BTDC
If you’re showing 35 advance at idle you’re dist is possibly on the wrong drive cog and is against the locking stud and you’re not able to retard the idle
The lead point of the rotor should be just at the mark on the dist housing for #1. Rotation is CCW
The pod and vacuum advance would be gotten from the tapping of manifold 1 and 4 and running a vacuum line to the pod.
Any questions, PM me
Bruce

You may have the coaxial connections reversed.

Mysocal911. Thank you. The problem existed before replacing coaxial. Just discovered it was in very poor condition so thought it wise to replace. It has factory connectors so proper polarity should be maintained.

Bruce. Thank you. You are correct I am up against post with distributor adjustment. Fully CCW. I will try to see if I can correct this.

Also - check to see if you get more advance as you increase RPM. Some race cars lock the advance at full advance (35 deg) and it doesn't change with RPM. Your engine obviously has many modifications done to it, and now you have to try and unravel what someone else has done.

What you need to do to get the timing correct
Pulley on Z1 dist cap removed. You want your rotor Leading edge coming up to the mark On the dist base. If it’s not pull the dist about 1/2 way out and position the rotor to the right of the mark and seat the dist. You should be able to adjust the rotation of the dist so the rotor is coming to the mark.
You need to reconfirm firing order in the cap so you know you’re correct and you’re on the right #1 connection on cap.
Bruce

Thank you everyone. Timing locked in for racing was not the issue but a good thing to check.

Bruce had done what you said in your last post and now working correctly. Albeit sucking on the vacuum hose myself. Now I have to plumb that in and road test. See if my mid range problem is solved. If not I will probably turn to the carbs and rebuild them/accelerator pumps. Looked to me more like fuel pouring in rather than an atomized spray.

Thanks again everyone. Hope you all are keeping well.

Could be that the mechanical advance unit is frozen? Pull the cap and see if the rotor can move freeley a few degrees CCW and spring back.

Thanks Gordon.

Just checked and rotor moves freely and springs back.

Hello all,

Car has now developed a problem that I experienced previously but not as extreme. Previously felt like a miss or lurching above 3000 rpm with sputtering/popping at carbs.

Now the car is undriveable. Applying throttle nearing 3k and it violently bucks and lurches. RPms are all over the place.

Timing is close at idle but is not steady. Maybe a 2-4 degree swing. I have replaced the Bosch. Oil with a new MSD as I was also going to swap out the permatune for an MSD.

I didn’t fully tear down carb but took out idle jets and cleaned. Also took both accelerator pumps apart and all parts looked new. Diaphragms were not torn.

I’ve had dizzy out and it seems to be functioning. Vacuum advance is hooked up and functions.

So looking for ideas. I’m thinking permatune or dizzy are my problem.

Any help is always appreciated.

Should also mention it now has a new Porsche dizzy cap and rotor.

So what happens when you rev the motor with the timing light on? Is the advance working?

What about fuel flow? Bad pump or clogged filter?

I’m thinking it’s a fuel pump. I have a new one to swap in and am going to try that next. Thanks Gordon.

Still having issues. Bucks wildly around 3K. If I coax it slowly I can go a bit higher without the bucking and surging until close to 4K.

To recap what I have done and tried

-new plugs. Bosch factory spec.
-new wires. Clewitt.
-new cap and rotor. Porsche.
-new fuel lines. Len.
-PMO fuel block. Have installed a higher quality liquid filled gauge.
-tried 2 different pumps.
-jumpered fuel pump relay. Only with ignition in on position to check fuel pressure.
-3 different fuel filters.
-timing is now dialed in at idle. Am unable to check all in timing due to my issue above.
-with Bosch coil and MSD coil. Same issue.
-unable to increase fuel pressure above 3lbs. Was at 3.5 and has now slipped. Should also note tach swings wildly when bucking surging.

So your running MSD? Is it a digital 6al? Interference is an issue with them.. Also is the carb linkage loosening getting them out of sync? If running MSD then polarity is a real issue .

The CDI is still Permatune. Used MSD coil to trouble shoot. Carb linkages look to be adjusted well and in sync. Will double check them.

Thanks to everyone who has offered advice for troubleshooting.

I now have hooked the fuel pump up direct to battery and it has increased pressure to 3.5 which I believe is correct for Weber’s. I am unable to bring it higher than that. I have a 3rd pump which I will try to see if it changes. Part of me wants to be able to increase pressures to 4-4.5 and see if any changes occur.

Your symptoms sound a lot like a distributor which is either frozen or not advancing as it should. I had that happen to me once. But when I knew what to look (feel) for, it was obvious - the advance stuff in the distributor had gotten gunked up, and you couldn't turn the rotor easily by hand as you should be able to do.

You could try rotating the distributor (leave the nut loose) as you try to increase the RPMs to check higher RPM timing. If you can get it to work better that way, you might be onto something.

A dial back to zero timing light isn't all that expensive. Lets you use the quite visible Z1 mark and quantify things.