Clarification on ignition upgrades

FrayAdjacent911 · 10-30-2005, 11:41 AM

So I am buying a '69 Targa from a couple local enthusiasts, and will be transplanting the engine from my '70. They suggested that the CD ignition system in the '70 is different from the '69. I also figure, while I'm doing the transplant, might as well upgrade the ignition system.

I'm a little unclear about it all. I'm looking at a Crane optical unit, and the MSD units. From what I gather, the MSD only controls the spark and such, and the Crane unit replaces the points system to control timing. Is that correct? Would you have to use both units in order to get the point replacement, timing control and spark control, or will one or the other unit do it all?

Also, what are the differences between the '69 and '70 ignition systems (while we're at it)

dd74 · 10-30-2005, 11:44 AM

Subscribing out of interest. Good questions, Fray...

project 911 · project 911's Garage

Maybe this will help a little.

You can get just the Crane optical points replacement kit. I got mine from our host. It works with your stock ignition (CD box) and will work with your stock tach. Pretty painless to install and wire.

The MSD and Crane Fireball (and others) replace your stock CD box and controls your spark. There are different opinions on this, with some saying that the Bosch CD system is perfect the way it is. Others say that going with an MSD system improved performance.

Keep in mind that going to an MSD system may require a new coil, possibly new plug wires (they recommend spiral core), maybe a tach adapter, mounting the CD box, etc. I think 70-71 tachs are a problem with these systems. I never did get mine to work with the MSD.

Not sure about the differences between 69 & 70 systems.

FrayAdjacent911 · 10-30-2005, 07:49 PM

Steve, thanks, that helps a lot. I found a Crane Fireball XR700 kit on Ebay for a little over a C note, and figured I'd get it. With my engine having the wrong distributor on it (70 T engine with a 68 or 69 Bosch distributor with two part points. Maybe a PO had a Marelli and couldn't find parts, and only found the Bosch? Who knows?). Switching to a more modern ignition setup would be desireable for me.

Early_S_Man · 10-30-2005, 09:47 PM

The '68 and '69 911T engines [being a cost-reduced price leader model] had conventional battery-coil ignitions with condensers mounted on the distributor.

All 1970 model 911s had Bosch CDI ignition.

FrayAdjacent911 · 10-30-2005, 10:43 PM

S man, did the 69 and 70 use different coils? Pelican's parts listing shows the same coil for 69-73.

If I end up getting that Crane unit, and I have both distributors available to me (the one from the 70, which works, and the one from the 69, which hasn't run in about 15 years) which coil would I use with the unit?

911pcars · 10-30-2005, 10:53 PM

"I'm a little unclear about it all. I'm looking at a Crane optical unit, and the MSD units. From what I gather, the MSD only controls the spark and such, and the Crane unit replaces the points system to control timing. Is that correct? Would you have to use both units in order to get the point replacement, timing control and spark control, or will one or the other unit do it all? "

Crane, Pertronix, Accel and Mallory manufacture optical ignition triggers. They also make spark boxes, both inductive and CD types. Optical triggers work with their own control box as well as with higher output ignition boxes.

I use a Crane optical unit (XR700) along with their Hi-6S ignition box.

Sherwood
http://members.rennlist.org/911pcars

Early_S_Man · 10-31-2005, 03:32 AM

Fray,

The Pelican listing for '69 - '73 coils is for 911E and 911S models/engines only, as the 1969 911T did not have CDI, and would use a different coil!

My strong suggestion is to transplant the OEM Bosch CDI ignition along with the engine ... the wiring changes to the 1969 911T harness will be fairly trivial. Get the stock ignition working before you plan any great 'upgrades' that won't get you any additional power or reliability!

For the install ... you will need the Ballast Unit [a three-terminal resistive divider for the tach input circuit] and CDI unit from the 1970 electrical panel ... and the coil mounted on the fan housing of the '70 engine. The following is a shot of the 1970 relay/regulator panel where the #3 Ballast Unit, and #9 CDI unit reside:

Grady Clay · 10-31-2005, 06:46 AM

Matt,

I’m assuming this is a carbureted ’69 911T and a carbureted ’70 911T. Is the ’69 engine dead? Is the ’70 chassis in distress?

You will want to use the engine wiring harness from the ’69 engine. That will make the conversion easy (it has the three round connectors near the RR upper shock mount.) You should carry over the voltage regulator from the ’70. As Warren said you should carry over the Bosch CDI from the ‘70 and the little separate wiring harness for the Bosch CDI. The ’70 ignition transformer stays with the ’70 engine and Bosch CDI.

The electric panel on the ’69 has a mounting cut-out for the #3 “RPM Sensor“ in Warren’s image. (That image is for a ’72 but is very similar to your ’70.) The “RPM Sensor” is also known as “Switching SCR” and “Intermediate Unit” and is only on ‘70s (not ‘71s) and ’69 E & S. It should not be confused with the “RPM Transducer” that is part of the MFI system.

With the clutch, you have two choices: First you can swap the smaller 215 mm clutch and flywheel from the ’69 onto the ’70 engine. The second option would be to also swap the ’70 transmission into the ’69 which would allow you to keep the larger 225 mm clutch of the ’70. That includes the clutch cable and possibly the pedal assembly. The axles, shift linkage, etc. will fit without change.

You should carefully inspect the carburetors. It may be desirable to swap the Weber carburetors with the Zenith carbs that came on the ’70. The same may be the case with the ’69 Bosch distributor and the ’70 Marelli. Don’t do this until after the swap is up and running properly.

If the ’69 has been sitting, it would be a good idea to pull the fuel sender and inspect the bottom of the fuel tank.

If you plan any maintenance or upgrades to the ’70 engine; do them first and get everything well sorted out. It isn’t any fun to be trouble shooting five things simultaneously.

Depending on what you want to do, I have more questions.

Best,
Grady

FrayAdjacent911 · 10-31-2005, 08:12 AM

Grady, thanks for the advice.

As far as the engine in the 69, water got into the engine via the carburettors, and it's pretty much toast. I am buying the car from a couple other local enthusiasts who found it and intended to part it all out and then sell me the tub so I could cut/patch areas of my coupe that need it. However, the 69 Targa was so complete, and the tub is in great condition, we all thought the same thing - it will be easier for me to get it up and working than my coupe.

The guys that bought it did take a few things out of it already (jpnovak from this board, and another local guy with a 912 are the guys that found it and got it) The carburettors on the 69 were Webers that were in decent condition, but they have already sold those.

My '70 is pretty much a stock 2.2l T engine with Zenith carbs. The only upgrade I can tell has been done are the Carrera chain tensioners, and the distributor not being the correct Bosch unit for that year.

I will have all of the wiring available for the engine swap, so if the wiring conversion is easy, then that will be of great help.

Also, we'll likely be trying to use my transmission. I have a brand new clutch in it, and will also pull the new clutch cable from the coupe. I do have the axles from both cars, but if the ones from the '70 will work, then it will be easy to make a decisin (whichever two look the best!)

The thing that Jamie was worried about was the front end of the transmission in the '70, since it was bulked up a bit, might not fit in the '69, due to the 'hump' between the rear seats not being big enough. Do you think this will be an issue?

As far as maintenance on the '70 engine, it needs a good cleaning. It's filthy. The carburettors could use cleaning, too. Then I have some leaks to chase down. It runs good, is very smooth in the 1500-3500rpm range, but starts to feel a little vibration above 4000rpm. Doesn't seem to burn off much oil, as I did a 700+ mile round trip, and didn't see much in the way of oil loss according to the dipstick. It does smoke a little bit, and backfires through the exhaust when decelerating, but seems to be pretty normal.

Grady Clay · 10-31-2005, 08:41 AM

Matt,

Take the pedal assembly from the ’70 and rebuild it. There is some discussion about the clutch arm ratio different in ’70-’71. Let me know when you do this, I’d like you to measure the two back-to-back.

Also consider which car has the best (least rust) oil tank and fuel tank.

The transmission is an easy swap and it fits perfectly (it’s the ’72 -> 915 that has the fit issue.)

Looks like you are headed for an open 911. I wouldn’t part with your ’70 for a while after the ’69 is up an running. You may find other things you want to swap (vented brakes?)

Best,
Grady

FrayAdjacent911 · 10-31-2005, 09:26 AM

Grady,

I'll pull the pedal assembly from the coupe... it may be rusted in there, and might be a little bit of a pain in the butt to get out.

The gas tank from the Targa was toast. There was a big hole near the front, and the back seam was looking really bad. The tank in my coupe is in much better shape. I plan on getting it flushed and sealed soon, and then I'll refinish the exterior and get some undercoating on the bottomside. (I read that Wurth SKS matches the original finish of the tank perfectly)

Glad to hear the transmission will fit, that's one less obstacle out of the way.

The oil tank in the Targa should be good. When they drained the oil, they said it came out looking OK.

I'll be hanging on to the coupe for a while. Gonna start parting it out early next year when I get a place with a garage. I am swapping the brakes over from the coupe since I rebuilt them last year. The front rotors are just about at the minimum thickness, so I ordered a new pair of vented rotors. Also have all new front bearings incoming.

Thanks for the information! You help make this place the best place to come for Porsche knowledge!

Grady Clay · 10-31-2005, 10:28 AM

Matt,

Since the Targa isn’t running (yet) take the oil tank out for cleaning & inspection. One of the insidious things with nice old 911s is the oil tank can rust – from the inside. There isn’t any filter or screen between the tank and all the important stuff. All the rust flakes go into the engine. While the bearings can absorb just so much, I have seen a flake plug a cam oiling hole and loose a cam lobe and rocker arm.

If the Targa’s gas tank was rusty, what is the condition of the front pan?

While the pedal assembly may be a pita to get out, it is worth the effort.

Is the ’69 trans still in the Targa? Is it aluminum case or mag case? Is it for sale?

Good that you are going to take your time parting the coupe. All the best of two cars and then some can go to the Targa. How is the Targa top and seals?

Best,
Grady

FrayAdjacent911 · 10-31-2005, 10:48 AM

Grady,

The front pan in the Targa had been replaced at some point, and it was a very professional job. The welds look very nice. There's a little surface corrosion on the top under where the tank was. Not bad at all. A little treatment and some POR 15, and it will be fine. The undercarriage is nice and solid. In a couple areas on the floor pans, the undercoating has worn off, and there is some surface corrosion, but again, not deep and not bad. It will treat easily. My short term plans include getting the car up in the summer, and stripping the undercoating off then recoating.

I will go ahead and pull the oil tank and clean it up. I'd much rather side with caution.

The trans from the '69 is sitting in Morrie's garage. You can inquire with Pelican member JPNovak about the transmission. I believe they will sell it since I likely won't need it.

The targa top is actually in really good condition. It's a bit dirty, but it works, and will look good with a little cleaning. The seals on the window and targa bar, unfortunately, are pretty much shot.

Overall, I'm gonna like the Targa more than the coupe. I have no intention of tracking it, or making it super duper fast or anything. I just want a nice classic Porsche for a weekend driver and for fun.

FrayAdjacent911 · 10-31-2005, 12:59 PM

Anyone got a good scan of the 69 and 70 wiring diagrams?

I've heard that the Haynes manual has good diagrams. I have the manual, so I'll check it. I was just wondering if anyone had any scans (preferrably in color) that I can look over online. I'll have to wait until Friday to go get the book.

And Grady, I'll see about extracting both of the pedal clusters and will compare them and let you know what I find.

911pcars · 10-31-2005, 08:40 PM

Matt,
I scanned some early wiring diagrams here:

http://members.rennlist.org/911pcars/WiringDiag.htm

Sherwood

FrayAdjacent911 · 10-31-2005, 08:53 PM

Sherwood, NICE!! Thanks for the link!

I have some wiring diagram, but I'm not sure which specific year it's from. I'll look at the ones you've got up there. Probably end up putting some on a disk and going to Kinkos for some hard copies.

Thanks!

911pcars · 10-31-2005, 09:31 PM

Matt,
I use the number of fuses to ID the correct wiring diagram. Still, there are some items not accounted for.

Hope this helps,
Sherwood

Early_S_Man · 11-01-2005, 07:45 AM

Matt,

For some strange reason ... there isn't a diagram for the '69 'T' in the factory service manual. The fact that there was an 'E' and 'S' specific diagram, i.e., the SL33 diagram on Sherwood's site ... would imply that there should have been a 911T-specific diagram, but that job must have fallen through the cracks for the newhire engineers that year.

Use the SL33 diagram as a guide as to what you want the wiring after the transplant to look like regarding CDI, Ballast Unit [intermediate unit, etc.], tach, coil, and distributor ...

The SL35 diagram is mislabeled on Sherwood's site ... it is only a 1970-specific diagram, and doesn't refer to any '69 model, easily verified by the existence of the unique group of four six-pin bulkhead wiring connectors on the '69 models, and not present in 1970 model wiring ... superceded by the two 14-pin connectors on the electrical relay/fuse/regulator panel!

FrayAdjacent911 · 11-01-2005, 12:14 PM

Thanks Warren. Thinking about it is starting to make my head spin!! I'm wondering if it will be easier to get the Crane unit to control the spark and replace the points system, and rig it into the 69's wiring, and just use the coil from the '70. Then all I have to make sure works is the blower and indicators. (right?)

Here's a picture of the victim, I mean, project: