For the 303 engine, the user manual (and the data tecnici book) specifies 8 deg fixed advance (on the engine) and 7.5 deg centrifugal advance (on the distributor).
Am I right in thinking that the equivalent centrifugal advance in crank degrees would be 15 deg, for a total advance of 27 deg?
And, the giri/min and gradi numbers on the data tecnici graph should be both doubled to get crank rpm and crank degrees?
Thanks,
Peter
Timing advance specification
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Peter Cripps
Re: Timing advance specification
Arithmetic slip-up ... I meant to say:
"Am I right in thinking that the equivalent centrifugal advance in crank degrees would be 15 deg, for a total advance of 23 deg?"
Side comment -- this doesn't seem like much advance ... I'm used to seeing figures in the range 30-35 deg for max total advance?
Peter
"Am I right in thinking that the equivalent centrifugal advance in crank degrees would be 15 deg, for a total advance of 23 deg?"
Side comment -- this doesn't seem like much advance ... I'm used to seeing figures in the range 30-35 deg for max total advance?
Peter
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Huib
Re: Timing advance specification
You read the figures correctly. I agree, it is not much. On the other hand there is no vacuum connection which would reduce the advance when you depress the throttle pedal.
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P. de R. Leclercq
Re: Timing advance specification
Well, the fact that the Fulvia requires only 23 degrees total advance, suggests that the combustion chamber design is really rather good.
I recall a piece concerning Cosworth's development of the horrid Ford Kent engine. This had the nasty "Heron" head with the combustion chambers in the pistons. Cosworth did very well in getting about 140HP from the 1300 c.c. version, but they needed something like 45 deg. of advance to get it. And given the weight of those nasty pistons I'll bet the con-rods were something special.
It's worth noting that the 1600 Fulvia is specified with 28 degrees of total advance. I have not really thought this over, but I wonder if it is to do with the fact that the 1600's valves are really rather small for the capacity, whilst the 1300's are more suitable (in size terms).
Paul
I recall a piece concerning Cosworth's development of the horrid Ford Kent engine. This had the nasty "Heron" head with the combustion chambers in the pistons. Cosworth did very well in getting about 140HP from the 1300 c.c. version, but they needed something like 45 deg. of advance to get it. And given the weight of those nasty pistons I'll bet the con-rods were something special.
It's worth noting that the 1600 Fulvia is specified with 28 degrees of total advance. I have not really thought this over, but I wonder if it is to do with the fact that the 1600's valves are really rather small for the capacity, whilst the 1300's are more suitable (in size terms).
Paul
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Peter Cripps
Re: Timing advance specification
Thanks Paul and Huib.
Reason I started to look at this was that I was getting some pinging when the engine was hot, at low-medium rpm. I had previously set the static timing at 10 deg, but at idle the timing light said more like 13 deg. And at 3000 rpm I was getting close to 30 deg.
Mind you, at full throttle the engine was pulling very well ...
Anyway, I've reset the timing to get 23 deg at 3000 rpm; we'll see how that works out.
Peter
Reason I started to look at this was that I was getting some pinging when the engine was hot, at low-medium rpm. I had previously set the static timing at 10 deg, but at idle the timing light said more like 13 deg. And at 3000 rpm I was getting close to 30 deg.
Mind you, at full throttle the engine was pulling very well ...
Anyway, I've reset the timing to get 23 deg at 3000 rpm; we'll see how that works out.
Peter