But I still don't believe them - look at the curves for torque and HP in the Technical Data Book, do the sums and I think you will find that they don't add up!
Paul
camshafts
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Christopher Adams
Re: camshafts
The cam timing on Coupe 1.3 Rallye, Rallye S, 1.3 Series 2, HF Fanalone, HF Series 2 is supposedly:
Intake, open 28 degrees , close 66 degrees
Exhaust, open 66 degrees , close 28 degrees
The cam timing on Coupe 1.2 HF & 1.3 HF is supposedly:
Intake, open 24 degrees , close 72 degrees
Exhaust, open 72 degrees , close 24 degrees
I can't find figures on lift.
Compare those figures with contemporary Fiat twin cams:
1438cc 124 AC Coupe & 1608cc 124 BC Coupe:
Intake, open 26 degrees , close 66 degrees
Exhaust, open 66 degrees , close 26 degrees
for valve sizes 42mm / 36mm with 9.5mm lift.
These were regarded as long duration and quite 'cammy' and were used as a hot cam in the 2 litre engines when being modified. I'm not totally sure about this as although the later cams had shorter duration they had higher lift so maybe the benefit was imaginary?
According to Guy Croft from his book on tuning twincam Fiat lumps, for a 1600cc engine the progression from 'fast road' to 'full race' is:
Fast Road (all based on a 131 1600 cc twin cam)
Intake, open 5 degrees , close 53 degrees
Exhaust, open 53 degrees , close 5 degrees
for valve sizes 42mm / 36mm with 9.5mm lift.
Stage 2
Intake, open 40 degrees , close 80 degrees
Exhaust, open 80 degrees , close 40 degrees
for valve sizes 42mm / 36mm with 10.4mm lift.
Stage 3
Intake, open 34 degrees , close 74 degrees
Exhaust, open 74 degrees , close 34 degrees
for valve sizes 44mm / 36mm with 10.8mm lift.
Stage 4 Full Race
Intake, open 50 degrees , close 90 degrees
Exhaust, open 90 degrees , close 50 degrees
for valve sizes 45mm / 40mm with 10.9mm lift.
Paul, can you comment on your experience with the Fiat engines and if any of what works on the Fiats is applicable to the Fulvia engine?
Intake, open 28 degrees , close 66 degrees
Exhaust, open 66 degrees , close 28 degrees
The cam timing on Coupe 1.2 HF & 1.3 HF is supposedly:
Intake, open 24 degrees , close 72 degrees
Exhaust, open 72 degrees , close 24 degrees
I can't find figures on lift.
Compare those figures with contemporary Fiat twin cams:
1438cc 124 AC Coupe & 1608cc 124 BC Coupe:
Intake, open 26 degrees , close 66 degrees
Exhaust, open 66 degrees , close 26 degrees
for valve sizes 42mm / 36mm with 9.5mm lift.
These were regarded as long duration and quite 'cammy' and were used as a hot cam in the 2 litre engines when being modified. I'm not totally sure about this as although the later cams had shorter duration they had higher lift so maybe the benefit was imaginary?
According to Guy Croft from his book on tuning twincam Fiat lumps, for a 1600cc engine the progression from 'fast road' to 'full race' is:
Fast Road (all based on a 131 1600 cc twin cam)
Intake, open 5 degrees , close 53 degrees
Exhaust, open 53 degrees , close 5 degrees
for valve sizes 42mm / 36mm with 9.5mm lift.
Stage 2
Intake, open 40 degrees , close 80 degrees
Exhaust, open 80 degrees , close 40 degrees
for valve sizes 42mm / 36mm with 10.4mm lift.
Stage 3
Intake, open 34 degrees , close 74 degrees
Exhaust, open 74 degrees , close 34 degrees
for valve sizes 44mm / 36mm with 10.8mm lift.
Stage 4 Full Race
Intake, open 50 degrees , close 90 degrees
Exhaust, open 90 degrees , close 50 degrees
for valve sizes 45mm / 40mm with 10.9mm lift.
Paul, can you comment on your experience with the Fiat engines and if any of what works on the Fiats is applicable to the Fulvia engine?
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Peter Cripps
Re: camshafts
Just a quick observation on the figures for the Fiat cams: the later 5-53 timing was specified at 0.80mm clearance. At normal running clearance of 0.45mm intake, and 0.50mm exhaust, duration is significantly longer.
There has been quite a bit of discussion on Fiat cam profiles here in the USA. Several people, including myself, have measured earlier and later cams and found the profiles to be identical. There is a slight difference in timing though; the 5-53 version has peak lift at 114 deg, while the 22-66 is at 112 deg.
By comparison, the 26-66 Fulvia timing has peak lift at 110 deg. Applying the (perhaps over-simplified) view that more overlap means shifting the power peak to higher rpm, then the Fulvia cams are slightly hotter than the early Fiat cams.
I do realize that there's a lot more to this than where peak lift happens, of course.
Peter
There has been quite a bit of discussion on Fiat cam profiles here in the USA. Several people, including myself, have measured earlier and later cams and found the profiles to be identical. There is a slight difference in timing though; the 5-53 version has peak lift at 114 deg, while the 22-66 is at 112 deg.
By comparison, the 26-66 Fulvia timing has peak lift at 110 deg. Applying the (perhaps over-simplified) view that more overlap means shifting the power peak to higher rpm, then the Fulvia cams are slightly hotter than the early Fiat cams.
I do realize that there's a lot more to this than where peak lift happens, of course.
Peter
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Christopher Adams
Re: camshafts
Peter,
I have owned a variety of Fiats over the years including 124 BC coupe, 131Racing, & 130 Strada Abarth.
The different characteristics were quite marked with the 124 definitely being the most cammy, the 131 Racing had twin 45mm dellortos and was very strong, but ran out of top end, and the 130 Strada Abarth, was the best integrated balance with plenty of torque and good top end.
The biggest differences could be explained in terms of breathing rather than cam profile & timing, with the 130 Strada having the best flow, largest valves, and best exhaust arrangement. (All are 8 valve heads).
I don't know what relevance this has to the fulvia but thought that since there seems to be plenty more information floating around regarding Fiat / Lancia twin cam engine tuning, some of which may help with the original question.
I have owned a variety of Fiats over the years including 124 BC coupe, 131Racing, & 130 Strada Abarth.
The different characteristics were quite marked with the 124 definitely being the most cammy, the 131 Racing had twin 45mm dellortos and was very strong, but ran out of top end, and the 130 Strada Abarth, was the best integrated balance with plenty of torque and good top end.
The biggest differences could be explained in terms of breathing rather than cam profile & timing, with the 130 Strada having the best flow, largest valves, and best exhaust arrangement. (All are 8 valve heads).
I don't know what relevance this has to the fulvia but thought that since there seems to be plenty more information floating around regarding Fiat / Lancia twin cam engine tuning, some of which may help with the original question.
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Peter Cripps
Re: camshafts
Chris,
Interesting comments. I too have owned several Fiats, from a 1968 124AC coupe through to my present 1980 fuel injected 124 spider. The 124AC motor revved freely to 6500 rpm and beyond, while the FI spider starts running out of breath at much over 5500. I agree that most of the difference can be traced to breathing, since cam timing, valve sizes, and cylinder head design didn't really change all that much as the engine grew from 1438cc to 1995cc.
My Fulvia feels much more like the AC coupe ... you can feel power building nicely as revs increase. By comparison, the 1995cc FI engine feels more like an old-school V8, loads of torque low down, but a bit disappointing at higher rpm.
Anyway, probably enough non-Fulvia content from me!
Peter
Interesting comments. I too have owned several Fiats, from a 1968 124AC coupe through to my present 1980 fuel injected 124 spider. The 124AC motor revved freely to 6500 rpm and beyond, while the FI spider starts running out of breath at much over 5500. I agree that most of the difference can be traced to breathing, since cam timing, valve sizes, and cylinder head design didn't really change all that much as the engine grew from 1438cc to 1995cc.
My Fulvia feels much more like the AC coupe ... you can feel power building nicely as revs increase. By comparison, the 1995cc FI engine feels more like an old-school V8, loads of torque low down, but a bit disappointing at higher rpm.
Anyway, probably enough non-Fulvia content from me!
Peter
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Geoff
Re: camshafts
Yes there is a lot more, but this is a good starting point. Lobe centers (and the separation intake from exhaust) give a pretty good indication of "how hot is this cam?". Better than duration, for example.
The Aurelia is typically at 112-113 degrees. Stock street is around 115, with 110 getting warm, 100-105 very hot (too much for the street), and below that is radical for the track only.
The Fulvia at 110 degrees (was that the HF?) seems pretty good.
The Aurelia is typically at 112-113 degrees. Stock street is around 115, with 110 getting warm, 100-105 very hot (too much for the street), and below that is radical for the track only.
The Fulvia at 110 degrees (was that the HF?) seems pretty good.
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P. de R. Leclercq
Re: camshafts
Well Christopher,
There's a lot more to camshafts than straight timing figures; since the Fulvia and FIAT engines are totally different, I would consider any comparisons to be a blind alley.
Consider for example the shape of the Fulvia's cam follower (rocker). Not that it is curved where it meets the cam; imagine the effect on the opening and closing characteristic. Then regard the shape of the cam itself The Fulvia cam opens quite quickly but has a broad "nose" suggesting longer duration at full opening than a typical FIAT cam - again, bear in mind the profile of the rocker face!
So you see, it is not a straightforward matter!
Paul
There's a lot more to camshafts than straight timing figures; since the Fulvia and FIAT engines are totally different, I would consider any comparisons to be a blind alley.
Consider for example the shape of the Fulvia's cam follower (rocker). Not that it is curved where it meets the cam; imagine the effect on the opening and closing characteristic. Then regard the shape of the cam itself The Fulvia cam opens quite quickly but has a broad "nose" suggesting longer duration at full opening than a typical FIAT cam - again, bear in mind the profile of the rocker face!
So you see, it is not a straightforward matter!
Paul
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P. de R. Leclercq
Re: camshafts
Just as an aside, at Evo we used to offer an ex-works profile for Fulvias, that was copied from a pair of billet cams that Barry bought.
These were timed nominally at 50/70/70/50. And they provided 11.3mm of total lift, with 4.3mm at TDC.
Fitted to a Fulvia they provided considerable torque improvements, although more initial advance was necessary to remove flat spots.
A friend ran a special Fulvia: 82.4 x 69.7mm, with Kugelfischer injection. He used a pair of cams I bought from Dick Lewis. These were ground by Kent to a Ford cross-flow profile. Timing was 60/80/80/60, but lift was probably about the same as standard cams. The car went like a bomb until the block failed. Loads of steam - I was doing 115mph in my Dedra and he sailed past me with a big grin on hi face!
Who knows eh?
Paul
These were timed nominally at 50/70/70/50. And they provided 11.3mm of total lift, with 4.3mm at TDC.
Fitted to a Fulvia they provided considerable torque improvements, although more initial advance was necessary to remove flat spots.
A friend ran a special Fulvia: 82.4 x 69.7mm, with Kugelfischer injection. He used a pair of cams I bought from Dick Lewis. These were ground by Kent to a Ford cross-flow profile. Timing was 60/80/80/60, but lift was probably about the same as standard cams. The car went like a bomb until the block failed. Loads of steam - I was doing 115mph in my Dedra and he sailed past me with a big grin on hi face!
Who knows eh?
Paul
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Justin
Re: camshafts
Still brings a smile to my face!
I started her up the other day to circulate the antifreeze etc, and just the exhaust note is a joy, even though it's just a standard 1300 (still with Kugelfischer and exhaust and cams , of course).
Regds,
Jus
I started her up the other day to circulate the antifreeze etc, and just the exhaust note is a joy, even though it's just a standard 1300 (still with Kugelfischer and exhaust and cams , of course).
Regds,
Jus