Various Early 911 Questions

[domtoni]

1. Will an MSD ignition make a 2.0 911E run better below 3500 RPM? Can I expect significantly better fuel burning? My CDI is 30 years old, but it still works.

2. The car's muffler is also 37 years old, and done 66K miles. Could it produce alot of back pressure and should it be replaced?
If so, what is the M & K unit like, and how loud (in Db)? If it worth installing, can I expect improved peformance? Here in the UK, we are limited to 98 Db on the track, and I don't think I could get away with more than that on the street.

Thanks
Dom

PS, see my car on the 911E.org registry.

[silverc4s]

Dom,
Sorry; you are actually required to post a picture HERE to get answers to these kinds of questions..

Welcome to the best 911 websource anywhere.

[svandamme]

Originally posted by silverc4s
Dom,
Sorry; you are actually required to post a picture HERE to get answers to these kinds of questions..

Welcome to the best 911 websource anywhere.

just a pic of the car warrants one easy question answered
for full service a pic of said car , with a chick on top should be fine... we're not picky , any chick as long as it doesn't have feathers or wrinkles...

[randywebb]

- keep you stock CDI box; you could always buy and 'test' a MSD box if you wanted - the cost to run that experiment is a few hundred bux...

- it is unlikely that the muffler is now too restrictive. Is it the stock Porsche muffler, or some aftermarket item? I would replace it maybe if it is the latter, otherwise not.

Finally - it sounds like you would like to spend some money on the car! Don't worry, you'll be "able" to do that soon enuff.

If you want to spend $$ now, then look at the long term and neglected maintenance thread I started - things that will likely make the car more fun and safer include:
- replace rubber brake hoses
- replace every piece of rubber in the suspension
- replace trans. oil; and "tune" the shifter & coupler with new plastic pieces.

[targa911S]

Randy...come on we wanted chick pictures.

[svandamme]

he ruined it for the rest of us... i bet he doesn't drive a Targa either...
party poopers generally don't...

[randywebb]

yo! what about the poor guy with the questions??

besides - in his gratitude he may well post more pics than he would have otherwise

BTW - I have driven a targa - I admired the flexibility of it!

Now, would I own one? Sure - right after I get that NART spyder...

[svandamme]

Randy, the lad is from England, he'd do it to us just the same
besides, plenty of Essex girls around , they love to drape themselves over a car bonnet after a pint or 2... standard operational procedure over there.

[silverc4s]

Here's Dom's car. looks pretty nice to me - I love the yello/black combo on the early bodystyle..

[silverc4s]

[targa911S]

Too bad he had to tape those headlights on. Screws must be stripped out.

[jluetjen]

Originally posted by domtoni
1. Will an MSD ignition make a 2.0 911E run better below 3500 RPM? Can I expect significantly better fuel burning? My CDI is 30 years old, but it still works.

2. The car's muffler is also 37 years old, and done 66K miles. Could it produce alot of back pressure and should it be replaced?

I can conclusively say that the answer to your first question is YES. A multi-spark system will significantly clean up the driveability below 3000 RPM. Especially in the case of my 69E which has 2.0S pistons that exaserbate(?) the combustion issues with the 2.0 heads due to their steep valve angles.

As far as your second question, if your muffler is of the factory design, I doubt that age will increase the back pressure. I would expect age to rust a hole in it, but barring any holes, I would suspect that it works about as well as it always did.

[targa911S]

Originally posted by jluetjen
I can conclusively say that the answer to your first question is YES. A multi-spark system will significantly clean up the driveability below 3000 RPM. Especially in the case of my 69E which has 2.0S pistons that exaserbate(?) the combustion issues with the 2.0 heads due to their steep valve angles.

As far as your second question, if your muffler is of the factory design, I doubt that age will increase the back pressure. I would expect age to rust a hole in it, but barring any holes, I would suspect that it works about as well as it always did.

I agree...totally.

[domtoni]

Thanks Willi for posting the pictures.

I am not sure if the car is well set up (I bought the 911S front end back in 1975 and it was a race type front suspension), or I am not going fast enough.

Once I get the details sorted, then back to the track!!!

Thanks for the kind remarks. I am replacing the oil tank to sump hoses, the brake hoses (now with SS but 20 years old), a rusted brake tube that will fail.

I just want to get the car running good again. Read my history and the car's on the 911E.org web site.

Best
Dom

[domtoni]

Thanks guys for all the info.

1. I think Svan should put some of those hot Veronica girls over his car. The Dutch girls are far better than those from Essex !!!

2. I think I will keep the standard CDI for the time being.

3. Better yet, I will save the muffler as well.

The chappie fixing the car suggested that the low speed performance would be improved with the multi spark discharge, and the muffler is on its last legs. The muffler is quiet, and doesn't have any holes. Just a big dent from when I tested the world famous Porsche throttle off over-steer.

Thanks again guys and C2S for posting the pictures.

Dom

[jpnovak]

Welcome to Pelican. Great car and even better... Great location! On the track where it should be.

I too agree with what has been said above. A multi-spark ignition will help low speed issues but I would not bother if the current CDI is working properly. If it ever has issues that would be the time to consider one.

[Grady Clay]

Dom,

The place to apply some lube (money) is to establish a baseline for all the things that affect the performance of the MFI. If your only complaint is slight misbehavior at part throttle and 3500 rpm, it may be right on the lean limit. That’s OK.

Your question about the CDI is a good one. The Bosch CDI is very good at getting sparkplugs to fire in potential fouling conditions; too cold plugs, too rich, light driving, cold weather, etc. This is because the system has a very short risetime of the spark.

It’s not as good as some later systems in getting a lean, low pressure mixture to consistently fire; light throttle, 3500 rpm. This results in the too common surge at 3500 and light throttle. The “fat” spark from a regular Kettering ignition system is actually better in these conditions.

The current generation of very powerful ignition systems have the best of both worlds; they can fire almost fowled plugs, have a long duration spark for light throttle lean mixtures, and are very good at high rpm and cylinder pressures.

If you change ignition systems, be sure and keep all the original components carefully stored so they can be refitted.


Do some Pelican searches on MFI, CMA, CMA2, and more. Collect all available information. Start yourself your own MFI book for both you and your mechanic.

Here is Check Measure Adjust (CMA)to get you started.

What degree of familiarity does your mechanic have with Porsche MFI? You (and he) want to become world class experts. We can help.

BTW, welcome to the Forum. You will find this an indispensable addition to be the caretaker of and enjoy your ‘69E.

Best,
Grady

[randywebb]

Kettering ignition system = regular ol' electric ignition w/o electronics but with a coil...

[domtoni]

Guys,

Thanks for all of your comments and assistance.

I got the car back yesterday, and the technical chap doing the job did a great job, and the car runs like a fast moving freight train.

More more shuddering (no longer too lean), and the engine sounds like it should !!!

Now, I can get on with all the other projects !!!

Ciao
Dom

[silverc4s]

Dom,
Glad to hear it ! ! Shoot some more pics the next time you are at the track and keep us posted..