Project Mickey Mouse - Build thread of 79 SC I bought on eBay

[Alan L]

Ouch. Good find. Justifies pulling the engine.
Cam timing OK to check in car - but adjusting is way harder.
Makes sense to check while you have it out. 2 steps foward - i backwards.
Sounds like a lot or P stories/rebuilds. Including my own. At times I swear it was 3 steps backwards.
But you plug on and eventually the reward is there.
Alan

[Focker]

Thanks everyone for the support. Was feeling pretty discouraged before, but I think I'm on the right track now. I picked up some beefier 10ga wire to feed the ignition system

[Mr Beau]

The ring gear may have been a good fuse.

Might also want to double check that you don't have one of the cams 180* out, not that your symptoms indicate such an issue.

[Alan L]

I bought my 930 over a live Yahoo auction in Japan. I am in New Zealand. Bottom of the world. Hard to get parts.
The car was advertised as good to go with freshly rebuilt engine. Perfect.
When it arrived it took me about 2 months to get the engine to fire. Hrs of diagnostics - jumped relays, burnt wiring under the dash, etc etc. Finally had to pull the engine - clutch was stuffed, no synchros in g/box. Turns out during a teardown, I discovered the rebuilt engine consisted of a 2nd hand P/C and about half a pound of RTV. Rust in part of the body - filled out with a recent edition of some Japanese newspaper and freshly painted over. Every job I went to tackle just identified more undiscovered issues. 3 steps backwards.
Lost count of how many times I pulled the engine out .
15 yrs on would not trade it for any $s now. Drive it like I stole it. Just back from 2 days racing this arvo. There was a time I wondered if I should just sell it for parts - could not see how I could get myself out of the hole I had dug.
Alan

[Focker]

The only thing that makes me question or second guess cam timing is that I have a rothsport crank pulley and the markings are kind of crappy.

[Alan L]

You only need a TDC mark for cam timing.
Is that not clear on the pulley? If not, you can make your own mark - once you find TDC with a dial gauge. Not hard, with the engine out. Maybe worth doing anyway - put your own marks on while you have access. You can make 10-20 deg marks etc if you need.
Alan

[Long Nose]

I recently had a very similar issue. Had the gearbox rebuilt (was a 901 Gearbox) and installed a high torque starter, and got this:

Maybe those high torque starters are hard on the Porsche ring gear...

[Jonny042]

Bump for updates!

[Focker]

Not a ton to report - I did get the clutch back in after replacing the starter ring.

Kids sports and June filing deadlines are pushing back the completion date, but still hoping to at least get a few miles in this year. Hope to make some progress next week.

OH! I did run a fresh 10AWG wire from the starter directly to the relays for the ignition in case the hard starting was voltage drop.

[911 SLANT]

Know what you mean. Feel for you. No rush buddy. At least you own a classic Porsche. Like a fine wine. It takes time to get there. Enjoy the journey!

[Focker]

Carved out a few hours for myself today and got the motor back in the car.

Engine cranks like a champ, great oil pressure, no funny noises.

I removed and cleaned all 12 plugs with the lower plugs looking a bit sooty.

I had run new power wires to the relays for the coils. The engine wants to start with some cough and stumbles but no start.

All 6 of the header tunes get warm, so no dead cylinders, but unfortunately no start.

Next thing I'm going to try is a more robust ground wire for the electromotive coils.

I get the odd pop back through the carbs, so it must be spark problems, right?

One thing that seems odd is that the engine has a harder time cranking with the throttle wide open. That's weird, right?

Anyway, back to work and kids until the end of the month.

Wish me luck, and let me know if you have any advice!

Maybe I should video it trying to start next weekend.

[Uwon]

Just came across this thread and finished reading it. Great build by a fellow Canuck!
Looking forward to your updates.
Cheers,
Johan

[Jonny042]

Originally Posted by Focker

Carved out a few hours for myself today and got the motor back in the car.

Engine cranks like a champ, great oil pressure, no funny noises.

Yay for that!!!!

Originally Posted by Focker

I removed and cleaned all 12 plugs with the lower plugs looking a bit sooty.

I wouldn't read anything into the plug condition at this point. However, what plugs are you using and what are they gapped at?

Originally Posted by Focker

I had run new power wires to the relays for the coils. The engine wants to start with some cough and stumbles but no start.

All 6 of the header tunes get warm, so no dead cylinders, but unfortunately no start.

Next thing I'm going to try is a more robust ground wire for the electromotive coils.

As long as the ground is short and to the motor you probably aren't going to gain anything here.

Originally Posted by Focker

I get the odd pop back through the carbs, so it must be spark problems, right?

Nope, that's going to happen, especially with carbs, and tends to happen even at idle when they are cold and can indicate a lean misfire I think - at least it means your getting some spark and isn't a cause for concern in itself. BUT it COULD indicate ill-timed or erratic sparks, or a spark timing isssue.

Originally Posted by Focker

One thing that seems odd is that the engine has a harder time cranking with the throttle wide open. That's weird, right?

Normal, but only as long as it's not severe. More air getting into motor and takes more work to turn over. But is it possible your battery is getting low from all this cranking? It could still crank over but the voltage could drop to some pretty low level.

Originally Posted by Focker

Anyway, back to work and kids until the end of the month.

Wish me luck, and let me know if you have any advice!

Maybe I should video it trying to start next weekend.

I would check, double check, and triple check that the spark plug wires go to the right cylinders, assuming you have triple coils with wasted spark, Cylinder 1 should be paired with 4, 6 with 3, and 2 with 5?

Also, check, double check, and triple check your spark timing with a good old fashioned "DUMB" timing light. A dial type thinks too much and will give erroneous readings due to the wasted "extra" spark.

I suppose if you have top and bottom plugs that the two systems are essentially redundant, it might be easier to fire up on just the top set of plugs for now - fewer parts and fewer variables.

[Jonny042]

PS - sorry for the weird post if you subscribe to this thread!

Last thing - PMO's have no cold start enrichment at all, correct? You are going to have to pump the accelerator like crazy to get that thing to start!!! I suppose some starting fluid might be fun to play with but is a last resort I'd say and isn't going to fix anything.

[Jonny042]

Last, but not least, welcome back!!! Hope things start (no pun intended) to go better. Something tells me that with a little forward progress you'll find it easier to carve out more time for the car.

All the best, Jon

[Focker]

Thanks so much for the advice!

I'll recheck the spark plug wires and try running just one set of plugs.

Plugs are NGK BR6EK. Chose those based on a post from Paul at performance oriented. Plugs are gapped at .035.

I don't have a timing light, was unsure what to get. Just buy the cheap non adjustable ones since it's wasted spark?

It's crossed my mind to switch to stock Bosch plugs just to get the car running.

[Mr Beau]

Pop back through the carbs is lean, or ignition timing that is way off. Through exhaust is rich.

If you have a distributor with points, you could put crank pulley to 10* BTDC on #1 compression, pull #1 ignition wire and install a plug on the end, then move the distributor back and forth until you see a spark at this crank position. Not sure if there's an equivalent method with Electromotive.

But a standard timing light can be used to do the same. Disconnect all the spark plugs and verify #1 is firing near 10* BTDC while cranking. Might want to pull all the plugs to reduce load on the rod bearings and starter.

[Jonny042]

Originally Posted by Focker

Thanks so much for the advice!

I'll recheck the spark plug wires and try running just one set of plugs.

Plugs are NGK BR6EK. Chose those based on a post from Paul at performance oriented. Plugs are gapped at .035.

I don't have a timing light, was unsure what to get. Just buy the cheap non adjustable ones since it's wasted spark?

It's crossed my mind to switch to stock Bosch plugs just to get the car running.

It's possible the manual for the system gives a firing order for a straight 6 or something in which case it would be wrong in the manual. Also then I assume maybe you have to program the electromotive system for firing order so double check that too? The default could be for a straight six or something.

Those are some kind weird plug that I've never heard of. Paul knows his stuff so he's maybe not wrong about them. BR6EK sounds like a non-projected tip to me (the "P" in BPR6EIX which I use) and the pics I found seemed like they are some sort of multi-ground electrode plug?

So the funny multi-ground electrode is good but I think the coil pack fires one plug at opposite polarity to the other (usually the centre is positive). From the NGK website:

Wasted spark ignition systems are a type of DIS, which uses one coil for every two cylinders. The coil provides the spark for one of the paired cylinders on the compression stroke and to the other on the exhaust stroke. Because the coil fires the spark plug on the exhaust stroke as well, it is appropriately named 'wasted spark ignition'. In effect, the spark plugs fire simultaneously and twice as often.

Ignition CoilOne of the two paired spark plugs is always negative polarity while the other spark plug is always positive polarity. Negative polarity means the spark plug's center electrode is negatively charged and its ground electrode is positively charged. Positive polarity is the opposite. Each time the plug fires, a rapid exchange of the protons and electrons occurs, called ionization.

The negatively charged electrons will be attracted to whichever side of the spark plug that is positively charged. The positively charged protons have much more mass than electrons, and thus cause more wear on the electrode they collide with. Hence, one plug will exhibit more wear on its ground electrode, while the other plug will experience more wear on its center electrode. If a spark plug with a precious metal on only the center electrode were to be used with this type of ignition system, there would be uneven wear on half the plugs. Although single precious metal or standard nickel plugs will still allow the engine to run, plug life will be greatly reduced.

Therefore, if a vehicle was originally equipped with dual precious metal spark plugs, replacement with a single precious metal or standard nickel plug may reduce plug life and engine performance.

So I think you need to delve into spark plug choice, find one with precious metal on the centre AND the ground. Bosch does 'em, no idea what the right number would be.

Last, but not least, how do you know what your timing is set at right now, if you don't have a timing light? When you do get one, it would be an idea to make sure the timing on 1 and 4 match and happen at the right time, 6 and 3 happen 120 degrees after (on the crank pulley) and then 2 and 5 120 after that.

THEN you'll have no doubt about the timing, and the firing order.

Hope that helps!

[Focker]

I'll double check the plugs, I likely misspoke as they are a single ground strap plug.

Wish me luck!

[Focker]

Jon are you using Iridium plugs?