Tune Sequence

[Peter Coomaraswamy]

Now that my project is "home" I need to give her some tuning up. I got the technical info, but was wondering if someone(s) would chime in regarding the proper sequence of doing a complete tune up. Plugs and wires have been replaced, all original spec parts, nothing fancy, Bosch parts. I'm running points now, but I could use some help on where and what to connect the vacuum advance/retard, and basically what works best for the folks who have done this before. If there is a recommended post on this please point it out to me. I also have dual Webers and she's a 74 auto with the 5 speed conversion done. 93K on the clock and otherwise pretty much stock.

Thanks,

 

[Stevehose]

I am a big fan of the Pertronix electronic ignition so I'd reccomend replacing the points with that, you'll never worry about wear or adjusting them again. Carl N sells them at a good price and can reccomend the right model for your car.

Bosch W7DC or Beru BP6ES plugs gapped at .028-.030 with Pertronix

Leave the retard port disconnected at the distributor, this was used for emmissions and it increases idle temperature. Cap off any and all manifold vacuum ports on the webers and intake manifolds. You can connect the manifold ports together with a hose for smoother idling.

Run a ported vacuum hose from a weber to the advance port on the distributor, cap the other weber port. Disconnect and plug all the other emissions stuff. Check for vacuum leaks.

The difference between ported and manifold vacuum is manifold vacuum is suppied below the level of the throttle plate, ported is above it. So manifold vacuum is high at idle and drops off as throttle is opened, vice versa for ported vacuum. Some people use manifold vacuum for distributor advance (myself included) but this is a personal choice based on this debate. Stock is ported vacuum source.

Set the timimg per the manual with the advance vacuum plugged.

Here's a thread on tuning and synching the carbs (applicable to webers):

http://www.e9coupe.com/forum/showthread.php?t=10942

 

[Peter Coomaraswamy]

Pretty much exactly what I was looking for, I'll do a little cut and paste so I have everything in one spot. Thanks and I'll post any interesting results. BTW, I did a compression test when I first bought the car and it was even across all 6. I forgot what my reading was so I ask, what would be a good/fair/poor reading? I just want to start at the very beginning and document everything.

Thanks!

 

[Stevehose]

It's good that all are even, for a stock engine I'd guess anywhere from 140-155 or so but others here would know more than I. Test with engine warm, all plugs out and throttles wide open when cranking.

Here's the thread on manifold balance tubes:

http://www.e9coupe.com/forum/showthread.php?t=10477

Pretty much exactly what I was looking for, I'll do a little cut and paste so I have everything in one spot. Thanks and I'll post any interesting results. BTW, I did a compression test when I first bought the car and it was even across all 6. I forgot what my reading was so I ask, what would be a good/fair/poor reading? I just want to start at the very beginning and document everything.

Thanks!

 

[Peter Coomaraswamy]

Results

Cold compression test- I know it's supposed to be warm- but needed to get a base line and she wasn't running; have 120-125 across all 6 cold. braker gap at .015, dwell at 34, RPM's at 1700 (now warm) strobing the bellhousing I can see a "Z" at 1700 RPM's, what does that indicate, I did the 5 speed conversion so maybe I got an "alpha flywheel" or could have been manufactured in ancient Greece? Seems to run good (in the garage)- I need to do some minor things before really test driving her. Please let me know if the Z means anything to anyone-

Thanks,

 

[David]

It's good that all are even, for a stock engine I'd guess anywhere from 140-155 or so but others here would know more than I. Test with engine warm, all plugs out and throttles wide open when cranking.

Here's the thread on manifold balance tubes:

http://www.e9coupe.com/forum/showthread.php?t=10477

I wanted to try the manifold balance tube, but I don't have any of the EGR parts and neither Carl, Peter or Jim have the manifold plugs anymore. With a thread of M10 x 1.0 has any one found a part that will thread in ? I tried plumbing stores, but no luck.

 

[DerSchwede]

Cold compression test- I know it's supposed to be warm- but needed to get a base line and she wasn't running; have 120-125 across all 6 cold. braker gap at .015, dwell at 34, RPM's at 1700 (now warm) strobing the bellhousing I can see a "Z" at 1700 RPM's, what does that indicate, I did the 5 speed conversion so maybe I got an "alpha flywheel" or could have been manufactured in ancient Greece? Seems to run good (in the garage)- I need to do some minor things before really test driving her. Please let me know if the Z means anything to anyone-

Thanks,

Z = Zündung, the german word for ignition.

 

[Stevehose]

The Z ball is what you use for advance timing, so your timing is correct.

Cold compression test- I know it's supposed to be warm- but needed to get a base line and she wasn't running; have 120-125 across all 6 cold. braker gap at .015, dwell at 34, RPM's at 1700 (now warm) strobing the bellhousing I can see a "Z" at 1700 RPM's, what does that indicate, I did the 5 speed conversion so maybe I got an "alpha flywheel" or could have been manufactured in ancient Greece? Seems to run good (in the garage)- I need to do some minor things before really test driving her. Please let me know if the Z means anything to anyone-

Thanks,

 

[Stevehose]

Are you looking to cap the ends of the fittings for the old metal EGR pipe used to connect to the underside of the manifolds or are your fittings missing and there's just a hole in the manifold? The fitting appears as #11 (11641257252) in the diagram.

I wanted to try the manifold balance tube, but I don't have any of the EGR parts and neither Carl, Peter or Jim have the manifold plugs anymore. With a thread of M10 x 1.0 has any one found a part that will thread in ? I tried plumbing stores, but no luck.

 

[Peter Coomaraswamy]

Thanks guys, with timing and dwell correct and all vacuum hoses connected and or plugged I seem to be getting allot of "popping" and a high idle,

When cold starting, the chokes started her at around 1900-2000 RPM, then she settled down to about 1200, performance was good then by the time I drove one mile the popping started and the idle lifted and basically I got her to work and let her sit. I ordered the Petronix from Ben @ La Jolla which should arrive mid week. I suspect carburetor issues, but I think you all would probably suggest waiting for the electronic ignition parts before jacking with the carbs?

But of course if I'm missing the big red button that says "run perfectly" please let me know where to find it

1974, 93K mi. dual Webers-5 Speed and "simplified exhaust".

 

[Stevehose]

Popping sounds to me like an air leak causing a lean condition, have you checked all hose fittings and capped all unused ones? Checked old EGR fittings under the manifolds for leaks? Carb to manifold and manifold to head gaskets all ok? You can spray starting fluid or carb cleaner around these to see if idle changes, if it does, you have a leak.

Thanks guys, with timing and dwell correct and all vacuum hoses connected and or plugged I seem to be getting allot of "popping" and a high idle,

When cold starting, the chokes started her at around 1900-2000 RPM, then she settled down to about 1200, performance was good then by the time I drove one mile the popping started and the idle lifted and basically I got her to work and let her sit. I ordered the Petronix from Ben @ La Jolla which should arrive mid week. I suspect carburetor issues, but I think you all would probably suggest waiting for the electronic ignition parts before jacking with the carbs?

But of course if I'm missing the big red button that says "run perfectly" please let me know where to find it

1974, 93K mi. dual Webers-5 Speed and "simplified exhaust".

 

[Peter Coomaraswamy]

Right on Steve, I'll inspect and test. I wish I could help with the issue you are having, sorry- I just don't know enough or have enough experience to add anything but I really hope you find the problem and it's a simple one.

 

[Stevehose]

Thanks, I am going at this Tony Montana style - taking out anything that might be a possibility :razz: and whatever survives will go in the spare kit.

Right on Steve, I'll inspect and test. I wish I could help with the issue you are having, sorry- I just don't know enough or have enough experience to add anything but I really hope you find the problem and it's a simple one.

 

[David]

Are you looking to cap the ends of the fittings for the old metal EGR pipe used to connect to the underside of the manifolds or are your fittings missing and there's just a hole in the manifold? The fitting appears as #11 (11641257252) in the diagram.

Yep, that's it--the #11 fittings. I have plugs in the holes from Carl right now. #11 is listed as NLA and everyone I asks says they tossed theirs when removing the smog.

 

[David]

Leave the retard port disconnected at the distributor, this was used for emmissions and it increases idle temperature. Cap off any and all manifold vacuum ports on the webers and intake manifolds. You can connect the manifold ports together with a hose for smoother idling.

Run a ported vacuum hose from a weber to the advance port on the distributor, cap the other weber port. Disconnect and plug all the other emissions stuff. Check for vacuum leaks.

Set the timimg per the manual with the advance vacuum plugged.

I'm a little confused. Are you saying to disconnect and plug the advance side of the distributor during timing or to leave it connected to the carb ?

Also, should the retard be disconnected and plugged at the distributor and manifold ? ( to set the timing )

 

[Stevehose]

disconnect and plug (I use a golf tee) any vacuum line(s) attached at the distributor when setting the timing. Then reattach when finished. The idea is to take away any action of the advance mechanism of the distributor and it can't hurt to disable retard if hooked up too even though it is not present when revved that high.

I'm a little confused. Are you saying to disconnect and plug the advance side of the distributor during timing or to leave it connected to the carb ?

Also, should the retard be disconnected and plugged at the distributor and manifold ? ( to set the timing )

 

[David]

disconnect and plug (I use a golf tee) any vacuum line(s) attached at the distributor when setting the timing. Then reattach when finished. The idea is to take away any action of the advance mechanism of the distributor and it can't hurt to disable retard if hooked up too even though it is not present when revved that high.

Thanks. I did as suggested and reset the timing. I still don't think I have the infamous timing "ball", but I do have an adjustable strobe and used the OT mark and 22 degrees. Car doesn't diesel anymore, but still runs too rough. Ive been reading through older posts from you, 61Porsche, sfdon and others. If Im reading this right, I should also use a vacuum gauge while setting the timing. Would this gauge work for that ?

http://compare.ebay.com/like/111075369320

 

[Stevehose]

Yes the gauge is fine, some people use a gauge to time to highest idle manifold vacuum but this technique is debatable for our cars (I didn't feel comfortable with it) and can result in too much advance, I would time it per the manual like you did, if it is still not running smoothly then it's time to look for other causes like ignition/fuel delivery, carb balancing, or vacuum leaks.

2 gauges can be used (one on each carb), to assist with balancing, but the Carbmate is better because the big fluctuations in the vacuum gauge readings makes it difficult to fine tune. I am working on fitting some kind of damper to both of mine to reduce the flutter and will report if it works.

Thanks. I did as suggested and reset the timing. I still don't think I have the infamous timing "ball", but I do have an adjustable strobe and used the OT mark and 22 degrees. Car doesn't diesel anymore, but still runs too rough. Ive been reading through older posts from you, 61Porsche, sfdon and others. If Im reading this right, I should also use a vacuum gauge while setting the timing. Would this gauge work for that ?

http://compare.ebay.com/like/111075369320