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Discussion Starter #1
I have searched the forums and can't seem to find this addressed directly.

Will a Centerline ID405 Distributor work well in a 1600 motor? I have a '66 duetto and am looking to ditch the points. The Centerline distributor looks like a simple option and many people appear happy with it. I have also read that the 1600 motor wants something like 39 to 40 degrees of advance and the centerline distributor only offers 34 degrees. The nice people at centerline say that it will work "fine". So is "fine" good or only o.k.?

I'm a bit of a hack when it comes to these details so any help you all can give would be great.

Thanks,

Ron
 

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It will work better than the stock one. Unleaded fuel burns faster than the unleaded that the early distributor was designed for, so unleaded fuel needs less advance. You should also get some more torque and economy with the lower advance, the unleaded fuel will burn more efficiently.
 

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I am certainly not trying to knock the Centerline dizzy but: compare the factory advance curves of 1600 and 2L motors before you make your decision. The 1600 Veloce, SS and GTZ had static at 4/6 BTDC and max at 43/49 BTDC. The carburetted 1750 and 2L engines had 2/4 BTDC and 37/40. All of the smaller engines (except the GTA) had longer advance curves than the bigger engines.
 

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Ed: the answer is in the differences of the fuels that were available from the time Alfa created the curves and todays unleaded fuels. The early fuels with tetra ethylene additives burned much slower to lesson knock in the early engines. Todays fuels burn faster and do not need as much spark lead time to have peak combustion pressures. Too much spark lead time with todays fuels creates negative torque.

A lot of testing on the Sun distributor machine and on many test mule cars was done to come up with this curve. While they work on 90% of the Nord engines, race engines need to have a curve created for the build reciepe for each, which is something that I do for the racers.
 

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Might I suggest the RML electronic dizzy ......
Many here use it and have been happy with the result.
Also about $100 cheaper.......
 

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Discussion Starter #6
Thank you all for the replies. I ordered the centerline unit today and plan to install this weekend. I'll post back my impression when it is in.
 

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Hi George,
I am not challenging any of that. I was simply pointing out that smaller Alfa engines had longer advance curves than bigger engines and that a curve that is optimised for a 2L engine may not be optimum for a 1.6.
 

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Ed: the answer is in the differences of the fuels that were available from the time Alfa created the curves and todays unleaded fuels. The early fuels with tetra ethylene additives burned much slower to lesson knock in the early engines. Todays fuels burn faster and do not need as much spark lead time to have peak combustion pressures. Too much spark lead time with todays fuels creates negative torque.

Thanks for posting this, George. This answers some questions I've had for a long time---ever since reading some comments by David Vizard. It's easy to forget that, with these old cars (old owners too :)) we are also dealing with old technology. Wonderfully so, but still some distance away from things like contemporary fuel mixtures.
 

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Dyno test: 110 octane vs premium unleaded

Something interesting, Jim:
Some years ago I dyno'd two 2ltr race engines. They had the same porting, cams, exhaust, carbs, etc. The only difference was one had 13:1 pistons and ran on 110 octane fuel, the other had 10.4:1 pistons with the head milled to get 11:1CR and ran on premium pump gas.
The 13:1 engine needed 38 degrees of total advance to put out about 10 foot pounds of torque over the 11:1 engine at 33 degrees total advance.
As I recall the 13:1 had only about 15 horsepower difference at 400 more rpm
Since then I've had good results working to build in torque and not horsepower using pump gas on the Nord engines.
 

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Fuels

I suspect that the effect of fuels on ignition advance is being over-stated. I have a friend who races a GTV6 and a Milano and also has a GTV6 road car. He is a current SCCA regional champion with his GTV6. He owns his own dyno. He runs his motors on all kinds of gas - racing fuel and pump. I asked him specifically about ignition advance and fuels and his exact words were "I have not found that the type of fuel seems to matter."
 

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Discussion Starter #11
Installed

The centerline distributor arrived yesterday and I found a little time to intall it this morning. Installation was easy with a little lube on the O-ring to slide it in to place. I followed the instructions to set initial timing, connected the wires and turned the key. The engine sparked to life instantly and settled in to a nice idle. I hooked up the timing light and advanced the timing to 40deg at 4,500 rpm. This put the initial timing at about 10deg and raised the idle to around 1,000 rpm. Set like this I get almost to the "M" mark at 4,500 rpm. I could advance the timing a bit more but the idle would keep coming up.

Just as I finished setting everything and cleaning up the sun came out here in Southern California. I couldn't pass up the chance to see how it works in the real world. The first thing I noticed is that the idle is much more stable. However the biggest difference is in the throttle response. In the past the car has always had flat spots in the rpm range. Now it pulls instantly and continuously all the way to redline. My impression is that it is every bit as quick (or not quick) as it was before plus it drives so much better. Take off from a start is considerably easier. No longer do I have to bring the rpm's up a bunch and slip the clutch on a steep hill.

Clearly these are all set of the pants impressions and not dyno numbers. I don't know if it makes more or less horsepower or torque and to be honest I really don't care. I have cars that are much faster then this one (hell my suburban is faster) and I have cars that are slower like our '70 280se Cab. I own the duetto because it makes me smile and now it makes me smile even more.

Thanks again for all the help.

Ron
 

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A hearty WELL DONE is in order, then! :D
 

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Yo, Ron! Good on 'ya buddy! There are few things more satisfying than fixing your Alfa yourself and going for a drive in the sunshine. :)

If you find 1000rpm a little high, you can easily lower the idle without chaging your carburetor's syncronization. There's a horizontal screw just to the left of your linkage: back it out about a 1/2 turn and you'll lower the idle a bit.
 

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I know this is sorta off topic but since Ron's solved his problem I'll add this for everyone's greater edification. :)


The 13:1 engine needed 38 degrees of total advance to put out about 10 foot pounds of torque over the 11:1 engine at 33 degrees total advance.

Here's a good example, George. Yesterday afternoon I watched a friend dyno his 1600 101 Spider vintage racer: high compression w/ 33+/- advance, points w/MSD6. Going from .030 points gap to about 018 and 38 degrees advance made a huge difference! He started at about 90hp and by the 4th dyno pull was making 121hp at the wheels @ 6800! Nothing else was changed, just points gap and timing advance. Talk about money well spent!
 

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Discussion Starter #15
Yo, Ron! Good on 'ya buddy! There are few things more satisfying than fixing your Alfa yourself and going for a drive in the sunshine. :)

If you find 1000rpm a little high, you can easily lower the idle without chaging your carburetor's syncronization. There's a horizontal screw just to the left of your linkage: back it out about a 1/2 turn and you'll lower the idle a bit.
Funny I have been so focused on the ignition I completely forgot about the carbs. So I can easily turn down the idle at the carbs while advancing the initial timing. This would bring my total timing up to the 43deg the manual says but I'll have a bunch of initial timing. There must be some point at which this doesn't work or at least an optimal setting. How do you figure it out without a dyno?
 

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There must be some point at which this doesn't work or at least an optimal setting. How do you figure it out without a dyno?
[/QUOTE]

Timing light. :) Lower your idle speed, then use the timing light to determine were timing mark is. Loosen your distributor and turn it to line up the light with the mark. The rev your motor until your timing light shows max advance mark. You may have to go back and forth between setting idle speed and adjusting the timing to get it just right. Once everything is set be sure to tighten everything back up.
 

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Going from .030 points gap to about 018 and 38 degrees advance made a huge difference! He started at about 90hp...
Wow! With an 030 point gap I'm surprised it made as much as 90HP. :eek: Dwell couldn't have been, what, 35 degrees?
 

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Well, you can blame it all on the vaguries of a Kettering ignition. Remember when we used to think this was all sorta normal? With all the options avaliable it really doesn't make much sense to keep a points distributor, especially on a race-car. A Centerline brakerless or MSD breakerless distributor in in line.
 

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Only 7 years old

Considering changing the distributor in our spider, but waaay too confusing for me. Some say the 123. Thanks for the thread, I am ordering the Centerline ID 405 tomorrow. Seems a simple an effective solution for most of us.
 

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I am considering 123 for my 74 Spica 2000 GTV which is lightly modded. Curious to the advantages of the 123 over the centerline unit. I know the 123 offers a bevy of curves, but have read that #1 curve is best for 1750/2000 motors. Just trying to collect some Intel. Great thread btw!
 
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