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Discussion Starter · #1 ·
Any one had issues with the centrafugal advance not working smoothly? I finaly got the advance working but it has a hesitation around 2000 rpm where the engine coughs then slows before accelerating. I thought it may be something with the springs. Is there anywhere that I can get new ones?
 

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1969 Alfa Spider 1750 veloce.
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sounds like the advance is retarded
 

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Discussion Starter · #4 ·
It has webbers and the weights are free but when you rev the engine some time the idle speed goes back to 800 and sometimes it stops at 1200. When moving the rotor by hand there seems to be some rotation that is free before you feel any spring tension. That is why I feel the springs are no good.
 

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When they are old and haven't been taken care of properly the heels of the weights get a step worn into them where they ride on the cam because the cam is fixed but the weights have some float to them. The step is narrow and will ride on top of the cam and can cause it to hang up. You can file that step off but the weights are hardened so it's not easy. Also, completely disassemble and thoroughly clean everything. Use a touch of lithium grease between the cam and step - not much as any excess will just get flung off and end up on the inner wall of the distributor cap.

Marvel Mystery Oil is great for cleaning this kind of stuff up. Blow the excess off and reassemble.

The slack shouldn't be a problem as the weights will take a set at idle and that's when you will adjust your timing. As long as you can get the full advance range within the rpm specs you're good.
 

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Discussion Starter · #7 ·
Thanks Kcabpilot! I had not concidered that the play would be out as soon as you are at idle. I am getting the full advance but I am also getting some backfiering through one carb any ideas on that?
 

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Could be an intake leak. Spray some starting fluid (ether) around the base and manifold at idle, see if you get a surge.
 

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Discussion Starter · #10 ·
Lack of power on 73 alfa

Hi I think I might already know the answer to this one but just incase I thought I would pose it to the experts. The engine seems to be only fiering on 2 cylinders at idle, when I check the compression I get 90 on the front 2 and 70 on the back. I thought at that level I would seem a drop in performance but at idel I can pull both plug wiers off on the back 2 cylinders and there seems to be no change at all in the idel! Also when you run it up to about 3000 cylinder 2 burns back through the carb. What I am thinking is that the lack of compression and the poor idel are due to poorly seated intake valves and that it would also cause the back fiering. Any thoughts?
 

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Webers are often lean around 2000 rpm. You could try one size richer idle jets but IMO the solution is to use a high energy ignition and open up the plug gaps. The hotter spark will usually ignite the lean mixture and you will no longer have the stumble.
 

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those compression levels are far too low....how exactly did you carry out the compression test?
It needs to be carried out on a hot engine, all plugs out, and, full throttle whilst doing the test.
 
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