Lobe Separation Angle
- Thread starter xctasy
- Start date
From the XF-ZL-FE shop manual:
Carbed engines:
IO @ 22 BTDC @ .10mm lobe lift
IC @ 56 ABDC @ .15mm lobe lift
EO @ 58 BBDC @ .10mm lobe lift
EC @ 20 ATDC @ .15mm lobe lift
EFI Engines:
IO @ 24 BTDC @ .06mm lobe lift
IC @ 68 ABDC @ .12mm lobe lift
EO @ 62 BBDC @ .06mm lobe lift
EC @ 30 ATDC @ .12mm lobe lift
Lobe lift = 5.97mm (.235")
Rocker arm ratio = 1.73
The EFI cam is pretty stout for a stock cam.
Carbed engines:
IO @ 22 BTDC @ .10mm lobe lift
IC @ 56 ABDC @ .15mm lobe lift
EO @ 58 BBDC @ .10mm lobe lift
EC @ 20 ATDC @ .15mm lobe lift
EFI Engines:
IO @ 24 BTDC @ .06mm lobe lift
IC @ 68 ABDC @ .12mm lobe lift
EO @ 62 BBDC @ .06mm lobe lift
EC @ 30 ATDC @ .12mm lobe lift
Lobe lift = 5.97mm (.235")
Rocker arm ratio = 1.73
The EFI cam is pretty stout for a stock cam.
A
Anonymous
Guest
Id be interested in what the LSA is. I cant convert from those figures.
I have a few specs from Federal Mogul on there replacement cams.
cs-6015 = standard replacement in leaded carbed engine.
CAM LIFT VALVE LIFT DEG. DUR @ .050 LOBE SEP
----------------------------------------------------------------------
INT 0.235 0.406 190 108
EXH 0.235 0.406 190 108
CS-6016 = standard replacement in unleaded carbed engine
CAM LIFT VALVE LIFT DEG.DUR @ .050 LOBE SEP
---------------------------------------------------------------------------
INT 0.237 0.410 195 111
EXH 0.237 0.410 193 111
CS-6017 = use as standard replacement in efi or mild carb engine
CAM LIFT VALVE LIFT DEG.DUR @ .050 LOBE SEP
-------------------------------------------------------------------------------
INT 0.246 0.426 201 109
EXH 0.237 0.410 193 109
CS-1332 - good idle with lope,good mid to upper RPM power & torque
CAM LIFT VALVE LIFT DEG.DUR @ .050 LOBE SEP
---------------------------------------------------------------------------------
INT 0.286 0.495 214 111
EXH 0.286 0.495 214 111
DUR @ SAE = 291
INT SAE OPEN =40 INT SAE CLOSE =71
EXH SAE OPEN=82 EXH SAE CLOSE =29
BASIC RPM =2000---4800
Hope this of some use
cheers Dave
cs-6015 = standard replacement in leaded carbed engine.
CAM LIFT VALVE LIFT DEG. DUR @ .050 LOBE SEP
----------------------------------------------------------------------
INT 0.235 0.406 190 108
EXH 0.235 0.406 190 108
CS-6016 = standard replacement in unleaded carbed engine
CAM LIFT VALVE LIFT DEG.DUR @ .050 LOBE SEP
---------------------------------------------------------------------------
INT 0.237 0.410 195 111
EXH 0.237 0.410 193 111
CS-6017 = use as standard replacement in efi or mild carb engine
CAM LIFT VALVE LIFT DEG.DUR @ .050 LOBE SEP
-------------------------------------------------------------------------------
INT 0.246 0.426 201 109
EXH 0.237 0.410 193 109
CS-1332 - good idle with lope,good mid to upper RPM power & torque
CAM LIFT VALVE LIFT DEG.DUR @ .050 LOBE SEP
---------------------------------------------------------------------------------
INT 0.286 0.495 214 111
EXH 0.286 0.495 214 111
DUR @ SAE = 291
INT SAE OPEN =40 INT SAE CLOSE =71
EXH SAE OPEN=82 EXH SAE CLOSE =29
BASIC RPM =2000---4800
Hope this of some use
cheers Dave
Intake Lobe centre is (I.O + I.C.+180/2)-I.O
Exhast Lobe centre is (E.O + E.C.+180/2)-E.C
Lobe Centre Angle or Lobe Sepearation angle is the average of both
i.e 112 + 106
...............2
LSA = 109 Degrees.
For the carb,
(((22+56)+180)/2)-22) = 107 on intake
(((58+20)+180)/2)-20) = 109 on exhast
Average LSA of both is 108 deg
For the EFI,
(((24+68)+180)/2)-24) = 112 on intake
(((62+30)+180)/2)-30) = 106 on exhast
Average LSA of both is 109 deg
These cams could be made usefully wider in the LSA and can then cope with aggressive durations while working with an auto. Most later Falcons are very heavy, at 3500 pounds, so Ray Spence at Crow cams feels happier giving his cams a wide lobe
If you are inclined to run a manual, you used to go for a 106 LSA, if you could cope with the low-speed torque loss. On a light car like a Cortian, no probleman.
Log onto Crows web site, and all there 250 x-flow ones are on 112 centres, because most are autos, and Crows cam technology is further ahead than the earlier concepts.
The cam is the heartbeat. The trick is knowing what you want, and gearing it to suit. Gearing and cam selections can ensure your six makes a laughing stock of a hot V8 around town.
A
Anonymous
Guest
Execute (or others)
Could you go to this web and click on to street performance cams and see if you would choose either the CLH 212 or the CLH 215 the only difference is a small difference in LSA. From what is written and from the RPM ranges its sounds as if both behave differently . I have to get either one, as they work off a slightly lower lift (tommorrow or early next week).
They charge about $300 (figure they are probably worth it) for their cams and make many claims that are hard to ignore if there is any truth in them.
http://www.comeracing.com/
Could you go to this web and click on to street performance cams and see if you would choose either the CLH 212 or the CLH 215 the only difference is a small difference in LSA. From what is written and from the RPM ranges its sounds as if both behave differently . I have to get either one, as they work off a slightly lower lift (tommorrow or early next week).
They charge about $300 (figure they are probably worth it) for their cams and make many claims that are hard to ignore if there is any truth in them.
http://www.comeracing.com/
Tim,
the lobe centre has a 'rob peter give to paul' affect on power delivery.
The blurb from the Chevy Offroad and Marine guys is the standard party line on narrower LSA verses wider ones. Wide LSA's give great consistantly building torque,
1.best for heavy cars,
2.possibly with power steering,
3.possibly with air conditioning,
4.or autos with stock stall converter,
5.or situations where the car could fall into a hole off idle in the torque delivery.
The very reason Holden Gen iii/Chev LS-1's run wide LSA's is to give a nice wide torque band, great mean effective cylinder presures, and the result is good on anything that fullfills the 5 conditons above like this.
If you run
1. a manual,
2. light weight car,
3. with numerically high gearing,
then always go for a tighter lobe centre as it will give an excellent amount of off idle grunt which will really satisfy. There is a loss of low speed torque, and a big blobby gain just past the off-idle area.
The lobe centre controls a critical point....the amount of duration at which both valves are 50 thou off there seats This is a key area when you have an auto. Widen the lobe centre, you get less duration at 50 thou open. Tighten it, and you get more duration. A badly matched auto will die off idle if its not set up to build revs by the stall ratio or diff ratio. This is a primary reason why many cammed V8's fail to deliver on the street. Often, the extra mambo you get at 2700 on, comes right out of the early torque delivery. Especially when a stock Cleveland may have a 1650 rpm stall ratio which gets even lower if theres less torque. The Sam and Issy at C.O.M.E historically have been very particular about weight/trans/gear combos. The truth is, there are no wrong cams. There are only wrong periferals. If you build the combo to suit the cam, you'll win. If you cant change the periferals, then you have to change the cam to suit them.
the lobe centre has a 'rob peter give to paul' affect on power delivery.
The blurb from the Chevy Offroad and Marine guys is the standard party line on narrower LSA verses wider ones. Wide LSA's give great consistantly building torque,
1.best for heavy cars,
2.possibly with power steering,
3.possibly with air conditioning,
4.or autos with stock stall converter,
5.or situations where the car could fall into a hole off idle in the torque delivery.
The very reason Holden Gen iii/Chev LS-1's run wide LSA's is to give a nice wide torque band, great mean effective cylinder presures, and the result is good on anything that fullfills the 5 conditons above like this.
If you run
1. a manual,
2. light weight car,
3. with numerically high gearing,
then always go for a tighter lobe centre as it will give an excellent amount of off idle grunt which will really satisfy. There is a loss of low speed torque, and a big blobby gain just past the off-idle area.
The lobe centre controls a critical point....the amount of duration at which both valves are 50 thou off there seats This is a key area when you have an auto. Widen the lobe centre, you get less duration at 50 thou open. Tighten it, and you get more duration. A badly matched auto will die off idle if its not set up to build revs by the stall ratio or diff ratio. This is a primary reason why many cammed V8's fail to deliver on the street. Often, the extra mambo you get at 2700 on, comes right out of the early torque delivery. Especially when a stock Cleveland may have a 1650 rpm stall ratio which gets even lower if theres less torque. The Sam and Issy at C.O.M.E historically have been very particular about weight/trans/gear combos. The truth is, there are no wrong cams. There are only wrong periferals. If you build the combo to suit the cam, you'll win. If you cant change the periferals, then you have to change the cam to suit them.
A
Anonymous
Guest
I agree its very nice to have an engine that builds power very rapidly starting just of idle.
I have a 3.5 litre Magna it is silky smooth and linear but on occasions I hate waiting for it to build power. Many times at the lights I have given up the chase while waiting for it. Its not satisfying because its not there on demand.
Even with the low manifold velocity of my 2V with the 500 and its lack luster performance below about 2000 rpm it still kills the magna in the way it builds power from low rpm up. After driving the Cortina I tend to curse the Magna whenever in traffic, waiting for the Auto to change down exacerbates the problem more.
Wish Id kept the AU.
Thanks Cheers Tim
I have a 3.5 litre Magna it is silky smooth and linear but on occasions I hate waiting for it to build power. Many times at the lights I have given up the chase while waiting for it. Its not satisfying because its not there on demand.
Even with the low manifold velocity of my 2V with the 500 and its lack luster performance below about 2000 rpm it still kills the magna in the way it builds power from low rpm up. After driving the Cortina I tend to curse the Magna whenever in traffic, waiting for the Auto to change down exacerbates the problem more.
Wish Id kept the AU.
Thanks Cheers Tim
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