Ideal Camshaft Lobe Centreline Angle
Discussion
I've reported their posts and if all they want to do is try and derail this thread maybe the mods will delete their posts so people who actually want to learn something can plough through the thread more easily. I can't see how two pages of stupid pictures and a "whoosh" are helping this.
Big Al. said:
Guys if you can't keep this thread on topic your ability to contribute will be removed.
No more warnings!
As you were...
Site moderator.
fair comment al , in my paltry defense , i was really trying to create a more bonhomeous atmos ,and i assumed from db's comments to others on other threads, particularly that poor american chap ,he'd enjoy a bit of irony . oh how wrong i was !after realising the deep angst it had caused i was off to delete the pics ,since they had not lightened things ,but i see you'v done that allready ,thank you .No more warnings!
As you were...
Site moderator.
i will readjust my s o humour assemment threadwise ,and act accordingly .
with reference to the whole question of lsa ,
what i was trying ineptly to get at , is , is there really any such thing as an single perfect lsa ?
take an engine ,give it what you see as the perfect lsa ,now drive it and see what its like ..
lumpy tickover too much , spread the lobes a bit .top end dieing off to fast ,do the same .pk torque not high enough ? tighten them up a bit ,you made a new length induction ,creating more cylinder filling at xxx rpm ,now the lsa might need changing to cater for the increased resistance to reversion at those rpm ..etc etc
my point is ,that from a sort of 'holistic approach ' with the same engine ,the ideal lsa may vary and needs optimising ,for each circumstance ,so making the perfect lsa difficult to ascribe .
regards
robert
Edited by ivanhoew on Thursday 16th February 17:20
I think the point here is to try and lock down some factors that can have a major effect on LSA. It's better to get it within 1 or 2 degrees than 4 or 5.
Pumaracing is also saying that the current idea will not work for all engines.
Any new light on this subject will benefit everyone.
Pumaracing is also saying that the current idea will not work for all engines.
Any new light on this subject will benefit everyone.
carlt5 said:
Pumaracing said:
Your open/close figures and full lift figures contradict each other. I suggest you look more carefully at what cam timing numbers actually mean.
These are Fords own quoted figures I have measured both engines with dti and disc
the direct measurements agree [ within my accuracy of +/- 3deg on the open/close figures ]
This is why in my first post I say I am puzzled
Edited by carlt5 on Sunday 19th February 16:37
just roughly did this in a scrap of paper late in the evening so excuse me if i get it all wonky ,
looks as if all you cam lobes are 239 degrees duration ,
but timid in straight up you would have pk lift of:
cam 1 ....in 110.5....ex 113.5 112 lsa
cam 2 .....in116.5 ...ex 107.5 112 lsa
your timing on
1) in...1.5 degr advance and 5.5 degr adv on the ex .114 lsa
2) in... 4.5 degr ret and 3.5 ret on ex . 112.5 lsa
this equals a change in lsa on both .by 2 degr and 0.5 degr.
i'd guess the opening and closing ramps are pretty slow ,so a small change in lift can equal a greater change in timing .also , if they have fairly different ramps on opening and closing sides of the lobe , it can create this effect ,time it to pk lift and ignore the ramps is what i would do .
you may find that if you time it from, say 50 thou lift ,it makes more sense than off the seat timing .
ref the retard on the 2nd cam ,i would guess this was done to try to crutch a poor flowing head and make a little more top end . its quite a big change from the av advance of the first cam of 3.5degr ,to the retard of the second one of avg 4 degr.a swing of 7.5 degrees , which prob lost a bit of the bottom trq and put a little on the top .
id stick it in straight up .112degr on both.
hope that made some sense , bit tired so may be drivel !
regards
robert
editted for spelling ,and to add ,i dont know this engine very well (or at all) but i would imagine its got very poor pulse and inertia ramming ,,and so reversion is a tendency .the 112 lsa is wider than ideal to avoid crossover ,and give a smooth idle .again , its a consideration of all the factors that can create a compromise .
Edited by ivanhoew on Monday 20th February 07:28
ivanhoew said:
and i assumed from db's comments to others on other threads, particularly that poor american chap
You mean Stan Weiss? He's a friend of DV and I've known him from other online forums for several years. In fact it's a blessing he's still with us after the front porch collapsed when he was a toddler playing on it but luckily only the three hound dogs sleeping under it were killed. His parents were so proud when his first words as a baby were "Attention K-Mart shoppers". Recently when friends of his moved into a new house he was the first to volunteer to help them remove the wheels but it's a scurrilous rumour that he thinks a Volvo is part of the female anatomy.carlt5 said:
These engines are being used for Classic Trials so torque from idle under heavy load , often with WOT , is essential .[you are correct that 100e has more top ,the e93a has more low-mid]
On the 100e engine , I am intrigued as to why Ford would put the Inlet valve full open position so late in the cycle [121deg]
This is an engine with bore 2.5" , stroke 3.64" , Siamesed inlet [a la BMC 'A' series] sidevalve , 7:1 comp.
with so little valve overlap [ in open 3degBTDC/ex.close12degATDC] the engine is relying totally on piston depression for intake
surely getting the inlet valve fully open ,and keeping it open, would be optimal ?
What got me involved in this camshaft conundrum is when I purchased an Aquaplane Sport cam for Dads 100e engined Buckler [http://www.bucklercars.com/] and tried to time it in to their printed specs , I found the Inlet full lift was at 121deg [it is a regrind] - they state using the std timing marks and dowel, the inlet is fully open at 109deg.
So I started investigating [ Aquaplane were not interested and frankly rude and unhelpful]
I subsequently got in touch with their cam grinders , B+E Randle who sent me one of their own Historic Stock Car regrinds to try [ based on an old Mini Piper 285 profile]
obviously as it is a regrind the lobe centres can not be far from the std cam , but they have jiggled it a little , giving the full lift points - In 117,Ex 95 ,
so I made an 11deg offset dowel [ blob of weld and a file ! ] to equalise the In.+Ex. full lift at 106deg
The thing goes very well - but with massive fuel standoff from the twin 11/8" Su's at low/mid range full load WOT [ It is an open 2 seater you can smell and see the fuel ]
I suspect the 4-1 short primaries exhaust manifold is too restrictive
Anyway - back to the question -Any thoughts as to why Fords std inlet cam full lift timing on the 100e [ 121 deg] be so late in the cycle
did you mis this bit carl ? On the 100e engine , I am intrigued as to why Ford would put the Inlet valve full open position so late in the cycle [121deg]
This is an engine with bore 2.5" , stroke 3.64" , Siamesed inlet [a la BMC 'A' series] sidevalve , 7:1 comp.
with so little valve overlap [ in open 3degBTDC/ex.close12degATDC] the engine is relying totally on piston depression for intake
surely getting the inlet valve fully open ,and keeping it open, would be optimal ?
What got me involved in this camshaft conundrum is when I purchased an Aquaplane Sport cam for Dads 100e engined Buckler [http://www.bucklercars.com/] and tried to time it in to their printed specs , I found the Inlet full lift was at 121deg [it is a regrind] - they state using the std timing marks and dowel, the inlet is fully open at 109deg.
So I started investigating [ Aquaplane were not interested and frankly rude and unhelpful]
I subsequently got in touch with their cam grinders , B+E Randle who sent me one of their own Historic Stock Car regrinds to try [ based on an old Mini Piper 285 profile]
obviously as it is a regrind the lobe centres can not be far from the std cam , but they have jiggled it a little , giving the full lift points - In 117,Ex 95 ,
so I made an 11deg offset dowel [ blob of weld and a file ! ] to equalise the In.+Ex. full lift at 106deg
The thing goes very well - but with massive fuel standoff from the twin 11/8" Su's at low/mid range full load WOT [ It is an open 2 seater you can smell and see the fuel ]
I suspect the 4-1 short primaries exhaust manifold is too restrictive
Anyway - back to the question -Any thoughts as to why Fords std inlet cam full lift timing on the 100e [ 121 deg] be so late in the cycle
Edited by carlt5 on Monday 20th February 12:16
;)''ref the retard on the 2nd cam ,i would guess this was done to try to crutch a poor flowing head and make a little more top end ''
Edited by ivanhoew on Monday 20th February 14:16
Pumaracing said:
ivanhoew said:
and i assumed from db's comments to others on other threads, particularly that poor american chap
You mean Stan Weiss? He's a friend of DV and I've known him from other online forums for several years. In fact it's a blessing he's still with us after the front porch collapsed when he was a toddler playing on it but luckily only the three hound dogs sleeping under it were killed. His parents were so proud when his first words as a baby were "Attention K-Mart shoppers". Recently when friends of his moved into a new house he was the first to volunteer to help them remove the wheels but it's a scurrilous rumour that he thinks a Volvo is part of the female anatomy.I now see how people believe that you have missed you true calling. You are a master at the art of creating a great fictional tale.
Stan
carlt5 said:
ps can you please explain to this Numpty how a cam that gets the exhaust valve open to full lift in 110deg is the same as one that gets the exhaust valve open to full lift in 127deg
At a guess I'd say one with an LSA of 118.5 that is advanced by 8.5 degrees. Dave
Edited by DVandrews on Wednesday 22 February 08:16
carlt5 said:
so by advancing a cam you can make it open a valve from closed to full lift with 17deg less crank rotation ?
I don't know where you are getting that from.. going from 118.5 to 110 is 8.5 degrees *of timing change*, similarly going from 118.5 to 127 is also 8.5 degrees of change in the same direction. The open period from closed to full lift will remain the same, the lobe separation angle will remain the same, it's just that the open point is now earlier and since the full lift point is expressed as *after* TDC on the inlet, this will go down, but as it is expressed as *before* TDC on the exhaust it will go up... simples...When you advance a cam with fixed LSA the full lift point in degrees *reduces* on the inlet, but *increases* on the exhaust.
Give me the timings (open/close) of both lobes (inlet and exhaust) and provided the lobe is symetrical you can easily calculate MOP and LCA for each lobe and the LSA.
It isnt uncommon for cam manufacturers and engine manufacturers to give timing figures that dont include LCA, open/close is common, lift at TDC is common although usually backed up with an MOP.
If you are in doubt as to the timings, make the timing symetrical about TDC (same peak lift point inlet/exhaust) as a starter.
Primarily the discussion on the thread is about the prime determinants for the lobe separation angle, as this is fixed on your cams then this is strctly speaking a little of topic although allied since it covers LCA. Maybe some of the contributors seem unecessarily brusque, I would take it with a pinch of salt, it's not real life.
Dave
Edited by DVandrews on Wednesday 22 February 10:33
Stan Weiss said:
Pumaracing said:
ivanhoew said:
and i assumed from db's comments to others on other threads, particularly that poor american chap
You mean Stan Weiss? He's a friend of DV and I've known him from other online forums for several years. In fact it's a blessing he's still with us after the front porch collapsed when he was a toddler playing on it but luckily only the three hound dogs sleeping under it were killed. His parents were so proud when his first words as a baby were "Attention K-Mart shoppers". Recently when friends of his moved into a new house he was the first to volunteer to help them remove the wheels but it's a scurrilous rumour that he thinks a Volvo is part of the female anatomy.I now see how people believe that you have missed you true calling. You are a master at the art of creating a great fictional tale.
Stan
PS - you taken the "wide load" sign off the back of your house yet?
carlt5 said:
as I seem to be treading on some sensitive toes I will bugger off and carry on elsewhere
The problem is that this thread is about an aspect of camshaft science and your looking just to pick a nice cam for your engine, This thread is not about doing that. In a way you are hijacking this thread and it's not going down well with others.Pumaracing said:
Stan Weiss said:
Pumaracing said:
ivanhoew said:
and i assumed from db's comments to others on other threads, particularly that poor american chap
You mean Stan Weiss? He's a friend of DV and I've known him from other online forums for several years. In fact it's a blessing he's still with us after the front porch collapsed when he was a toddler playing on it but luckily only the three hound dogs sleeping under it were killed. His parents were so proud when his first words as a baby were "Attention K-Mart shoppers". Recently when friends of his moved into a new house he was the first to volunteer to help them remove the wheels but it's a scurrilous rumour that he thinks a Volvo is part of the female anatomy.I now see how people believe that you have missed you true calling. You are a master at the art of creating a great fictional tale.
Stan
PS - you taken the "wide load" sign off the back of your house yet?
You do know where DV lives?
While I live in a brick house, I have been in some very nice double-wides. Speaking of writting it is less than 15 miles from my house where the "Declaration of Independence" was written.Stan
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff