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Full Race Cam
- Thread starter mototron
- Start date
husky drvr
Platinum Level Sponsor
Might it be limited by what can be ground into a stock cam lobe? 
serIIalpine
Donation Time
ISky can make cams from your stock cam in the following grinds:
SBII .430 lift and 265 duration 228 @ 50
SBIII .430 lift and 286 duration 250@50
They make a SBIV as well.
They can also grind to your specs.
Eric
'62 SerII
SBII .430 lift and 265 duration 228 @ 50
SBIII .430 lift and 286 duration 250@50
They make a SBIV as well.
They can also grind to your specs.
Eric
'62 SerII
.430 lift= amount of lift at the valve. Usually assumes stock rocker arm, the actual lift at the cam is considerably less and not often given. May or may not compensate for valve clearance. Unless specified, it is safest to subtrack tappet clearance from that figure. Sometimes there is a notation of of "gross" lift. That means they assume zero tappet clearance.
286 duration. In that context (with no explanation and lift at .050" given), probably means the degrees of crankshaft rotation the valve is off the seat. Usually measured at about .002" lift.
250 @ 50". Really should be written 250 @ .050". The degrees of crankshaft rotation the valve is as least 50 thousandths of an inch off the seat.
For some reason, this type of data is common in the US, but not so in the rest of the world. It is very useful in determining the dynamics of the cam. For instance, the cam that is my Pinto engine has 15 degrees less off the seat duration than stock, but about 20 degrees more duration when measured at .050"
Bill
I'm sorry to thread-jack like this, but I'm curious-- how do we define a "full race cam" for the Alpine? Traditionally, "full race" refers to the point where low-rev tractability starts to seriously suffer, but how much lift and duration can the Alpine motor take before it becomes a torqueless screamer? Jan's chart on page 30 of issue 7 of the Alpine Marque shows that, besides the Isky specs quoted earlier in the thread, the normal 1600 cam has .366" lift and 246 degrees duration on the intake, and .364"/240 on the exhaust; the factory Le Mans cam (which, I've heard, doesn't spoil the Alpine's street manners that much) is quoted at .405" lift and 264 duration on both intake and exhaust. Meanwhile, if you ask a BMW 2002 driver, he'll tell you that a 286-degree cam is a good place to start for a bit more midrange power, and that you can go well past 300 degrees if you want the M10 motor to scream at the top end. So what do we count as "full race" (or, for that matter, "fast road" or "3/4 race") for the Alpine? Is it the SB-2? SB-3? The Le Mans grind?
RootesRacer
Donation Time
Raw cam timing specs dont tell much about what the cam actually is.
The above cam specs are either lash to lash (bigger numbers), or lift at X numbers (typ. .050). What is missing are the actual timing opening and closing specs, or at least the duration and lobe center specs. Additionally you need
to know the shape of the lobe itself which is seldom quantified by any grinder.
Therefore one grinders specs are more or less irrelevant as compared to another.
Your best bet is to deal with a single vender (Delta is as good as any), and to make relevant comparisons between their grinds and impact on idle and drivability.
Big cams (full race) often are useless on any thing other than heavily modified engines
since the power improvement cannot be realized without huge improvements
in port flow and higher RPMs than stock bottom ends can tolerate.
Ive seen "full race" cams destroy the low end torque of an engine while not
giving any high RPM torque back since the head, valves and carburettion was
not up to the task of supporting the overlap of the cam.
The above cam specs are either lash to lash (bigger numbers), or lift at X numbers (typ. .050). What is missing are the actual timing opening and closing specs, or at least the duration and lobe center specs. Additionally you need
to know the shape of the lobe itself which is seldom quantified by any grinder.
Therefore one grinders specs are more or less irrelevant as compared to another.
Your best bet is to deal with a single vender (Delta is as good as any), and to make relevant comparisons between their grinds and impact on idle and drivability.
Big cams (full race) often are useless on any thing other than heavily modified engines
since the power improvement cannot be realized without huge improvements
in port flow and higher RPMs than stock bottom ends can tolerate.
Ive seen "full race" cams destroy the low end torque of an engine while not
giving any high RPM torque back since the head, valves and carburettion was
not up to the task of supporting the overlap of the cam.
artic cat
Donation Time
zoom
I am thinking a cam is the means to an end. the end being to valves open and closed compared to the position of the piston. so to me the question is valve timing ie
do I get more power with the intake following the piston down on its intake stroke, then snapping shut at bdc. or should I keep the top travel of the piston low enough that my intake valve is fully open by the time the piston starts to travel down, but this means that I may have the intake and exhaust valves open at the same time.
it goes on and on and some people know the answers, best thing to do is find one and have them pick your brain as to what you want the motor to do for you, and the more specific you are the better they will do.
I would think that if someone is grinding a cam for me personally (not a production run) I will want to have some serious phone time with their engineer, and or ship them the engine so they get all the measurements they need like they want them to be sure the cam fits your application.
the block in these engines are tank like, I would like to see someone get 300-400 HP out of a very streetable version. if not drope in a 2.0L redline or gxp engine and trans (starting at 270 HP) then have it tuned up.
oops maybe 4cents worth there.
I am thinking a cam is the means to an end. the end being to valves open and closed compared to the position of the piston. so to me the question is valve timing ie
do I get more power with the intake following the piston down on its intake stroke, then snapping shut at bdc. or should I keep the top travel of the piston low enough that my intake valve is fully open by the time the piston starts to travel down, but this means that I may have the intake and exhaust valves open at the same time.
it goes on and on and some people know the answers, best thing to do is find one and have them pick your brain as to what you want the motor to do for you, and the more specific you are the better they will do.
I would think that if someone is grinding a cam for me personally (not a production run) I will want to have some serious phone time with their engineer, and or ship them the engine so they get all the measurements they need like they want them to be sure the cam fits your application.
the block in these engines are tank like, I would like to see someone get 300-400 HP out of a very streetable version. if not drope in a 2.0L redline or gxp engine and trans (starting at 270 HP) then have it tuned up.
oops maybe 4cents worth there.