Just noticed from Paul the timing of the 1016 cam shafts - I = 38/70, and E = 76/32.
A few things - first, the duration of these cams is still symmetrical at 288. Interestingly enough, that isn't so much different from the B22/B20 3rd and 4th series cams at 292.... So its not duration that makes these guys hot.
The lobe centers are 106 degrees for the intake (hot!) and 112 for the exhaust, averaging 109 overall. Typically on the Aurelia, the power was more commonly found by warming up the exhaust timing, but this seems to be different in the Fulvia.
Any thoughts?
camshafts
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P. de R. Leclercq
Re: camshafts
Well,
Erm, the Fulvia is a totally different engine:
- bore/stroke
- capacity
- relative valve size
- port shape and diameters
- valve gear
I think it is risky perhaps to generalise, but nevertheless interesting to contrast.
As for the Aurelia, I feel that there is power to be had with improved manifolding and system on the exhaust side.
Paul
Erm, the Fulvia is a totally different engine:
- bore/stroke
- capacity
- relative valve size
- port shape and diameters
- valve gear
I think it is risky perhaps to generalise, but nevertheless interesting to contrast.
As for the Aurelia, I feel that there is power to be had with improved manifolding and system on the exhaust side.
Paul
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P. de R. Leclercq
Re: camshafts
By the way,
I have never fully understood why the VAR 1016 camshafts whilst having longer duration, retain the same lift at TDC as the normal HF/303 camshafts.
Incidentally I have written a short piece about Fulvia camshafts that will be appearing on my blog quite soon under my "Fulvia Thoughts" series.
Paul
I have never fully understood why the VAR 1016 camshafts whilst having longer duration, retain the same lift at TDC as the normal HF/303 camshafts.
Incidentally I have written a short piece about Fulvia camshafts that will be appearing on my blog quite soon under my "Fulvia Thoughts" series.
Paul
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Geoff
Re: camshafts
Paul -
You are of course right - the Fulvia engine is quite different. One idea though is the matter of continuity at the Lancia design boards in the late 1950's and throughout the 1960's. Deep in the heart of the Italian engineering community lies a conservatism and a sense of continuity, and change only happened with careful consideration and slowly. For example, I have been told that Ferrari used the same lobe design in their cams for some 25 years or more.
Ideally, it would be nice to see the evolution of cam designs from de Virgilio through the Flaminia, and then the Flavia and Fulvia. FIrst, its probably easiest to start with how duration and lift were handled, and then (maybe) profiles.... but I'll wonder if the changes were in timing foremost, and only slowly in lift and in profile.
Nowadays, with computer controlled machining, the game is vastly changed - you can draw what you want and get it made. But then, how things were made was more considered (not necessarily better), and the linkage between the designers and the fabricators more direct. Of course, one has to unearth it, but that's part of the fun.
That's why it would be nice to see what the profile geometry of the Fulvia cam is.... anyone have any factory drawings? Is it still a tri-arc design? Were Flaminias like that?
And are Flavia cams similar to Fulvia cams, or did the Mina design of the Fulvia (if that was in fact the case!) extend as far as camshafts?
Ah, the questions!
Geoff
You are of course right - the Fulvia engine is quite different. One idea though is the matter of continuity at the Lancia design boards in the late 1950's and throughout the 1960's. Deep in the heart of the Italian engineering community lies a conservatism and a sense of continuity, and change only happened with careful consideration and slowly. For example, I have been told that Ferrari used the same lobe design in their cams for some 25 years or more.
Ideally, it would be nice to see the evolution of cam designs from de Virgilio through the Flaminia, and then the Flavia and Fulvia. FIrst, its probably easiest to start with how duration and lift were handled, and then (maybe) profiles.... but I'll wonder if the changes were in timing foremost, and only slowly in lift and in profile.
Nowadays, with computer controlled machining, the game is vastly changed - you can draw what you want and get it made. But then, how things were made was more considered (not necessarily better), and the linkage between the designers and the fabricators more direct. Of course, one has to unearth it, but that's part of the fun.
That's why it would be nice to see what the profile geometry of the Fulvia cam is.... anyone have any factory drawings? Is it still a tri-arc design? Were Flaminias like that?
And are Flavia cams similar to Fulvia cams, or did the Mina design of the Fulvia (if that was in fact the case!) extend as far as camshafts?
Ah, the questions!
Geoff
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P. de R. Leclercq
Re: camshafts
Geoff, Geoff!!
I shall have to do some re-writing on the camshaft piece for the blog.
And try to find a camshaft to photograph - many of my spares are still in England.
I will have to think harder in the face of all these challenges!
The Fulvia camshafts, certainly the later ones are not I think "tri-arc" - as the Flavia ones are.
I would think that the Flavia profiles are similar to the Aurelia's as the valve train is similar (pushrods are the same). The Fulvia profile - at least all the ones I have seen, apart from specials, has a "flat" portion after the initial opening part, with a broad nose. Again, remember the curved rockers which follow the cam...
Paul
I shall have to do some re-writing on the camshaft piece for the blog.
And try to find a camshaft to photograph - many of my spares are still in England.
I will have to think harder in the face of all these challenges!
The Fulvia camshafts, certainly the later ones are not I think "tri-arc" - as the Flavia ones are.
I would think that the Flavia profiles are similar to the Aurelia's as the valve train is similar (pushrods are the same). The Fulvia profile - at least all the ones I have seen, apart from specials, has a "flat" portion after the initial opening part, with a broad nose. Again, remember the curved rockers which follow the cam...
Paul
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Geoffrey Goldberg
Re: camshafts
Paul -
The challenges. I didn't know Flavia camshafts are tri-arc. Any idea on how to confirm that?
Thanks,
Geoff
The challenges. I didn't know Flavia camshafts are tri-arc. Any idea on how to confirm that?
Thanks,
Geoff
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P. de R. Leclercq
Re: camshafts
Er, well to be honest I don't exactly know what a tri-arc profile is. But I imagine from the name that it is the "traditional" shape if you know what I mean!
I have a book somewhere that might have some illustrations that I could scan to explain what I mean, but as I said before it is important to remember what the camshaft "sees".
Paul
I have a book somewhere that might have some illustrations that I could scan to explain what I mean, but as I said before it is important to remember what the camshaft "sees".
Paul
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Geoffrey Goldberg
Re: camshafts
Paul -
Tri- arc refers to the way Lancia (and some other designers at the time) designed the cam lobe - it is basically designed around the way a machinist would make the profiles: there are three arcs (of constant curvature).
1) the base circle
2) the top of the lobe (drawb as a portion of a circle, from a central radius point)
3) and then a gentle constant curve drawn to connect these two.
It turns out to be good for the machinist, as he could easily grasp what he wanted to make. It is not good for the valve, giving some rough acceleration at the start of the lift. It is (I think) in part responsible for the bad wearing of the valve train in the early Aurelias, and is improved in the later ones when they simply increased the size of the base circle and lobe (5th/6th series cars).
To see this geometry more directly - there are some images to be found at:
http://homepage.mac.com/geoffreyg/FileSharing14.html
These days, with better computer:machining linkages, we wouldn't do this. But then, communication with the pattern maker was as important as anything else, and the theory wasn't quite so developed.
If you are so motivated, I can send you some copies of early de Virgilio sketches from the 1940's where he is working out his cam lobe geometry, and you can see the progress from there!
Best,
Geoff
Tri- arc refers to the way Lancia (and some other designers at the time) designed the cam lobe - it is basically designed around the way a machinist would make the profiles: there are three arcs (of constant curvature).
1) the base circle
2) the top of the lobe (drawb as a portion of a circle, from a central radius point)
3) and then a gentle constant curve drawn to connect these two.
It turns out to be good for the machinist, as he could easily grasp what he wanted to make. It is not good for the valve, giving some rough acceleration at the start of the lift. It is (I think) in part responsible for the bad wearing of the valve train in the early Aurelias, and is improved in the later ones when they simply increased the size of the base circle and lobe (5th/6th series cars).
To see this geometry more directly - there are some images to be found at:
http://homepage.mac.com/geoffreyg/FileSharing14.html
These days, with better computer:machining linkages, we wouldn't do this. But then, communication with the pattern maker was as important as anything else, and the theory wasn't quite so developed.
If you are so motivated, I can send you some copies of early de Virgilio sketches from the 1940's where he is working out his cam lobe geometry, and you can see the progress from there!
Best,
Geoff
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P. de R. Leclercq
Re: camshafts
Thanks Geoff - that is exactly what I understood by "tri-arc" I am sure the Flavia cams are that sort of shape - indeed I am sure that many push-rod cars have cams that shape too. Jaguar XK cams certainly are, but again, flat followers!
Still searching for a picture for some other shapes!
Paul
Still searching for a picture for some other shapes!
Paul