Centerline dizzy advance curve - Alfa Romeo Bulletin Board & Forums
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post #1 of 30 (permalink) Old 09-16-2009, 06:14 PM Thread Starter
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Centerline dizzy advance curve

Help! first off let me say the folks at Centerline have been helpful in that they did send me another one.
My problem is the advance curve, on both distributors the advance really doesn't come in until about 2200 or so rpm. Above that it works great. I can see it under the light, as I slowly rev the engine the mark does not move until you get some revs. Like I said above that it swings nicely on up. BUT get below that and anything above idle and it provides nada advance. This makes a smooth take off from a stop light a clutch slipping adventure and the driveability below 2500 rpm frankly sucks. Has anyone else experienced anything like this with their distributor and what fixed it?
I've had the stock Marelli distributor in this engine and a Bosch 006 and they both bring in advance right off idle and when rapping the throttle good responce is there.
Rap the throttle from idle with the Centerline distributor and the engine falls on its face.
Help!
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post #2 of 30 (permalink) Old 09-17-2009, 10:16 AM
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More details needed: what are you setting as max advance? What modifacations are done to the engine? Carburation or Spica? Porting, cams etc.

Normally a higher initial will give faster throttle response below 2500 rpm. Have you tried retarding the initial and driving the car up to 4/4500 rpm to see if there is a better throttle response in the rpm range you say is not responding?

If you give more details, then maybe I can reset the curves on my distributor machine to suit your application.

George Willet


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post #3 of 30 (permalink) Old 09-17-2009, 05:59 PM Thread Starter
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Thanks, 73 GTV, 10:1 pistons, spica performance cams set at 102, msd6al igintion, head and manifolds ported to Jim K's specs, set of old shankle headers. SPICA car.
Have run a Bosch 006 with a "hot spark" magnetic pickup module and the stock distributor and driviability is fine with both. With the Centerline distributor installed and all else the same is when the problem appears.
I am setting at "M" or a little beyond as max advance, tried several positions under the light. Have tried setting the idle advance at "P" and "F". In all instances with the Centerline distributor the car will fall on its face when given gas rapidly. When given gas slowly under no load (I'm using the timing light) the revs will slowly come up but the pointer stays right where it is at idle until the revs reach around 2000 rpm then the pointer moves, well it doesn't move but the marks on the pulley move (advance). When I have either the Marelli or the Bosch distributor installed the marks begin to move the moment you touch the throttle, they don't with the centerline.
I have three distributors, 4 actually if you count the dual point stock from the 77 spider but I've never used that one. I have noticed with the Bosch 006 there is slight resistance when rotating the rotor by hand then it gets stiffer as you rotate the rotor further.
Same with the Marelli. A little resistane at first then the springs get tighter.
With the Centerline distributor there is a significant amount of resistance to rotor rotation from the get go. This is leading me to believe that the idle speed of the motor is not enough to overcome this intial resistance and give me some imediate spark advance hence the motor falling on it's face when given gas rapidly from idle. It raps up fine when I have the Bosch or the Marelli distributor installed and set at the F or P mark. I'm not concerned with what happens above 2500 rpm, the motor runs fine with all three distributors in that range.
Hope this helps, if you need more info I will certainly provide it.
Many, Many thanks!
I've talked with the guys at Centerline and they say they've never seen this particular problem.

edit, the 77 spider engine is completly stock except for eairler 2 piece exhaust header, from the 73, I've run both the Marelli and bosch 006 in the 77 with good throttle response from idle as well. I'm going to put the Centerline distributor in the 77 tomorrow and see if I experience the same problem.
Also this is the second Centerline distributor I've used, the first one did the same thing.

another edit, I was provided this info regarding advace timing for motronic pistions
Here's the Ideal timing for the Motronics: RPM
800 2000 3000 4000 4200 These are approximate.

8 23 31 35 36-37

I can absoultly say with high confidence that I do not have 23 degrees of advance at 2000 rpm with the centerline distributor. Can anyone out there recurve at a reasonable price my Centerline distributor to the specs above?

Last edited by gigem75; 09-17-2009 at 06:37 PM.
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post #4 of 30 (permalink) Old 09-18-2009, 11:07 AM
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Quote:
Originally Posted by gigem75 View Post
I am setting at "M" or a little beyond as max advance, tried several positions under the light. Have tried setting the idle advance at "P" and "F".
Michael, First, I am sorry you are having this problem and as you know we will continue to work with you to get it figured out.

This is not typical - the distributor should feel much livelier than what you are seeing. We have used it in many engines with similar specs. to yours with good results.

A couple of thoughts/suggestions:

I suspect you don't have things advanced enough, here's why: As per the instructions, you need to use a timing light with adjustable advance and set for 36 degrees max, this should give you an initial setting of about 10 degrees BTDC. You really must set for max advance and not worry about where the initial advance falls, I think this may be where things are going wrong.

For comparison, the factory "F" mark (1974, US Spec.) is at 5/7 degrees ATDC and the max advance is 27/33 degrees. That is a big difference from where the ID405 likes to be.

So, if you are anywhere near the factory initial advance mark "F" at idle, the ID405 will very feel sluggish, since you are starting from a very retarded initial mark. This would explain your lack of low-rpm response.

The other wild variable here is the MSD box. Now, I really can't think of any reason why the ID405 would not be compatible with this unit, but we don't recommend it and have not tested it. Our usual set up is simply the ID405 and a Bosch Blue Coil, which works well.
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post #5 of 30 (permalink) Old 09-18-2009, 01:38 PM
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Joe: I think you are on to something there. I recall there is something about the MSD polarity, and if reversed might affect the timing, indicated versus actual.

I have used the Centerline distributor in many engine combinations and have not experienced any performance difficulties or driveability issues. I have never used a MSD ignition though. Michael, try just a coil instead of the MSD unit.

George Willet


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Last edited by George Willet; 09-18-2009 at 01:43 PM.
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post #6 of 30 (permalink) Old 09-18-2009, 05:25 PM
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I am running an MSD 6AL with a 123 distributor with no problems, even though the 123 folks say it won't work. The MSD input just needs 12V on one wire and a timed closure to ground on the other. Any distributor that will fire a coil should fire an MSD.

Ed Prytherch
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76 Suzuki GT500
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post #7 of 30 (permalink) Old 09-18-2009, 06:29 PM Thread Starter
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I did that ran it with a coil and points on the 77 same thing, but my big question now is why is there only one advance spring in the distributor?

Last edited by gigem75; 09-18-2009 at 06:31 PM.
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post #8 of 30 (permalink) Old 09-18-2009, 07:15 PM Thread Starter
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Also I have run a bosch 006 with a magnetic pickup similiar to the pertronix ignitor that is in the Centerline distributor with the msd unit with no problems. I was under the impression that having two springs in the distributor would allow some quick intial advance to get off idle and then the other spring combined with the other longer spring would provide the curve on up to max advance. A distributor with just one spring would not be able to do this, at least I can't see how it would. Anyway I have reassembled the distributor with two springs using the lightest spring from the two spring kits I had purchased and can feel slight resistance to give the initial advance for good throttle response and then both springs come into play to work on the weights as the speed increases. Will road test tomorrow and let the world know the results.
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post #9 of 30 (permalink) Old 09-19-2009, 08:10 AM Thread Starter
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Inconclusive.... good driveability but too much tension on the second spring which allows a good max advance just past the "M" mark with intital set just past "P" but not quick enough, similiar to the curve of the 006 Bosch. Got one more spring to try.
My kingdom for an old Sun Distributor Machine!
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post #10 of 30 (permalink) Old 09-19-2009, 08:20 AM
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123---solution

123ignition electronic ignition systems for classic cars
Save yourselves a headache and install one of these.
There is a curve to cater for most requirements+the great spark balancing on idle. Reputedly F1 technology!
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post #11 of 30 (permalink) Old 09-19-2009, 07:17 PM Thread Starter
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I looked at that and trusted the Centerline folks had a good product. They do, it took some fiddeling to fit my set up but it works fine and I am happy with it. I'm glad I've got it in there. BTW I think it's safe to say that the MSD6AL works fine with the 405.
Just makes me wonder how fast the car would be if I had the 455 gears in the rear cause it will scoot pretty quick accerlation wise now. The 410 gears sure are nice on the highway and it will out drag race my 70 911T 2.2 so I'm a happy camper.
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post #12 of 30 (permalink) Old 09-20-2009, 10:51 AM
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Hi gigem75,
thanks for this thread, I tought I'm alone with my problems. I observed the same behaviour with my centerline distributor as you described. The advance starts only at 2400 rpm and causes a lot of misfiring and bucking, very bad rev until about 3000 rpm, from this point the cars rans very well. I cross-checked with stock distributor, starting at 1800 rpm, having a much better performance.

My question: how did you get the centerline distributor working?

My setup: Alfetta GTV 2000, 10.5:1 pistons, 297 degree cams with 11.6mm lift, two 40DCOE, jetting checked with a lambda-meter and seems to be pretty good.
Many thanks ind advance.
Ralf
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post #13 of 30 (permalink) Old 09-20-2009, 06:34 PM Thread Starter
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Thanks for your reply. It got me to dig a little deeper. My car is similiar to yours except for the spica and MSD6aL. I got decent driveability by doing what they said dial in 10deg BTDC timing at idle. Yep that fixed that all right and it was pretty late last night so I buttoned it up and did some other stuff around the house today, like put the single point Marrelli in my 77 Spider and took a long nice Sunday drive. Got back and saw your post so I thought maybe I'd better take the GTV out for one final check. Sure enough I had good driveability but out on a back country road when the tach hit about 6000rpm it sounded like someone threw a bunch of marbles into the engine. MAJOR DETONATION! I could pull 7000 rpm with the Marelli and the engine was happy doing it. I got the crap scared out of me going to 6500 with the Centerline distributor. Looks like you can have it one of two ways but not both. I'm sending it back tomorrow and they can do the right thing, either way this distributor is not the one for me. It might work fine for most but apparently not all. I put my Bosch 006 back in the GTV which has a "hot spark" magnetic pickup in it. It's not as good a curve as the Marelli and I might switch them back and put the 006 in the spider and the Marelli back in the GTV but at this point I'm going to give it a couple of days to let my frustration level come back down.
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post #14 of 30 (permalink) Old 09-20-2009, 07:26 PM
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The Bosch 006 is a very slow curve. I played around with the different advance curves in the 123. The 006 gave a nice slow idle but the pick up at low-mid rpm was not so good and it definitely gave poor mpg. The Bosch 045 is a good curve, well suited to a well tuned 2L.

Ed Prytherch
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2011 Jaguar XKR

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post #15 of 30 (permalink) Old 09-20-2009, 07:29 PM Thread Starter
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Where can I get an 045? thanks!
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