Mopar Performance Purple Mechanical Camshaft - P4120653AE Cam Card

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no such animal as the "perfect camshaft".
I hear that; I got lucky on my second pick. I am now on the third cam, which is just 7* bigger than the previous and from the same manufacturer, but I had to do a lot of fudging to finally like it, and it can't make fuel-economy for no amount of trying; as compared to the previous cam.
The first choice cam was not that horrible; it just didn't work with the gears I wanted to run. And, at that time, I was not ready to commit to purchasing an overdrive. Looking back, it would have been awesome with 4.30s and the GVod that I now run. It didn't suck gas any worse than the one I now have,lol.

Gain in one area and lose in another.
You said it!
Having the calculators available on-line, makes it so much easier to get your choices into the ballpark. Once there, you just call up your grinder and let him confirm or nix your choices, or recommend a better match. And you can then stop worrying about if it will meet your needs or not.
I don't recommend cams; I just give an opinion of what pressure and Ica might be complimentary.
 
Thanks AJ. You went the other way in explaining what I thought you were going to do. I thought you would show the same duration cams with events moved to show how the cylinder pressure drops. This has the feel of a smaller cam. Spreading the LSA from a 106 to a 114 is a massive amount. What happens on the dyno is another interesting thing.
 
We need a timing chain sprocket that will automatically advance the LSA as rpm increase's .
 
We need a timing chain sprocket that will automatically advance the LSA as rpm increase's .
It’s called a cam phaser. And most new fords have em.
BD949107-A1D6-4DC7-9BB7-A31D92901693.png

Problem is you need a two piece cam with intake lobes on one core and exhaust lobes on the other to really take advantage of it. And we cant even get standard mopar cam cores right now.
 
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Precisely, wouldn't that be a sweet bolt on performance piece.
It would be. With dual overhead cams it works well. I think Dodge, on the viper v10, made by Lamborghini, experimented with hollow cam cores to try and make it work. Not sure if they ever did.
 
A quote about LSA from the Erson cam catalog.

" The cam with closer lobe centers will always produce more power in the midrange than a can using the same profile with wide lobe center, & in many applications will produce more power all through the range depending on many variables such as the induction system, rod angularity & flow capacity of the ports."

Note two things.
- the use of the word always, not possibly or sometimes...
- rod angularity...
 
Thanks AJ. You went the other way in explaining what I thought you were going to do. I thought you would show the same duration cams with events moved to show how the cylinder pressure drops. This has the feel of a smaller cam. Spreading the LSA from a 106 to a 114 is a massive amount. What happens on the dyno is another interesting thing.
I was going to do that as well, but decided that the difference was too subtle to make the point.
And you are right. As the numbers show, from 114 to 106 while small to look at, the difference to the engine is "massive", perhaps even "tremendous", lol.
 
But ok lets do it!

The given will be a 340 cuber at 9.61 Scr; and lets stick to a known cam, the Mopar 340cam, that everyone so loves.
the specs are;
268 intake duration/ 276 exhaust duration/ ground on a 114LSA.
This cam has advertised overlap of 44*, and therefore the duration left for compression plus power is;
(360 x2+44) less (268+276) = 220* , which is a reasonably good number.
Lets install it at "straight up, and 4* in either direction, plus 8* advanced. So, the events are:
( in at/intake/comp/power/exhaust/Effective-overlap/Ica)
@-4*/268/108/112/276/32/72.....142/104
@+0*/268/112/108/276/40/68....148/113
@+4*/268/116/104/276/40/64....155/123
@+8*/268/120/100/276/32/60....161/132


Notice the 4* increasing march in the compression degrees, and
the 4* decreasing march in the power duration. These two on this cam, always add up to the 220(in blue), and are fixed in this relationship by the intake/exhaust/overlap.
Notice also the changes in Effective overlap(in red). Overlap is the time at near TDC when both valves are open, the intake is opening while the exhaust is closing. In this cam, the overlap by the math is 44*. But when you install it, about half goes to each side (split overlap), so the Effective overlap COULD be 44* .. But when you install it at some position other than split overlap, then the Effective overlap is less than 44*, namely, it is double the smallest number. Split overlap for this cam would be, in at 112*LSA.
If you don't know how overlap works, see note-1

Now, lets see what happens to the predicted cylinder pressures, at sealevel in the 9.61Scr 340 . Check out the final two columns which are pressure and VP. Notice the approximately increasing 6psi march in pressure. But also notice the more rapidly increasing march in VP. The VP is what you feel , from idle to stall, perhaps to as high as 3500rpm. Small numbers indicate small performance. Big numbers point to big performance.
For comparison to your favorite stock engines; the slanty makes a VP of around 87, the 273 around 100, the Smoggerteen is about 116, the 360 was about 126, the 318M is about 129, and the 10.5-340 comes in around 137.... by the numbers.
So then, as can be seen, the VP numbers that you need to target with a manual trans are about 130 or more. But with an automatic, you can get away with less, if you increase your stall-rpm. Personally, I feel that my combo with a VP over 159(at sealevel) is waaaay overkill..... but it is soooo much fun.

But back to the chart; look what happens to the Effective overlap, when you advance thechit out of this cam. You get the pressure, and the VP, but lose overlap big-time. Furthermore, the power extraction is down to 100* so the engine is leaving a lot of energy in the exhaust, energy that could have been used to propel the vehicle. This translates to excessive fuel consumption...........
Also; the high pressure translates to what makes the engine throttle response snappy around town, allowing you to run a bigger carb without the low-rpm sluggishness that often accompanies that choice.

Ok, gotta go to work, so EDIT; this was only half-finished at 7.30 this morning,lol.

note-1
O
verlap is the Fifth Cycle, and works almost exclusively with headers. What happens in the Fifth Cycle, is that the headers by their design, "yank" on the intake plenum during this time by the fact that the plenum is connected to the exhaust system during overlap. Log-manifolds to NOT pull on the intake. This yank/tug/ negative pressure; whatever you want to call it, gets the A/F mixture moving from the plenum, down the runners, and hopefully into the chambers, SOONER than is possible without overlap, and so begins the cylinder-filling process, sooner. The more overlap you have, the higher up into the rpm operating range, this process can continue. So for power production, the more overlap you have, the more power you will make while this process is in full swing. And this is no minor process.

By the way the cam is ground, a given set of lobes will, by way of the Fifth Cycle and headers, make more power the tighter you LSA them, ....... at the expense of Powerband. Therefore, you can tune a given cam to suit your trans or your weight, etc, by fudging with the LSA.
The A999/A500 have gearsplits of .56/.65
The A904/A727 have gearsplits of .59/.69
The A833 , ....has splits averaging .735
The GVod operating as a splitter, has splits averaging .79 thru the first two gears of the Commando box.

So as you can see, each of these transmissions has a different powerband requirement; the autos have only three gears to the A833s 4 gears; so naturally the powerband will need to be wider for it.................. right up until you install a very-high stall TC. For instance; if you shift at 6000 with a 4500TC, then your powerband requirement is just 1500 rpm or 4500/6000= .75, Aha!.
 
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But ok lets do it!

The given will be a 340 cuber at 9.61 Scr; and lets stick to a known cam, the Mopar 340cam, that everyone so loves.
the specs are;
268 intake duration/ 276 exhaust duration/ ground on a 114LSA.
This cam has advertised overlap of 44*, and therefore the duration left for compression plus power is;
(360 x2+44) less (268+276) = 220* , which is a reasonably good number.
Lets install it at "straight up, and 4* in either direction, plus 8* advanced. So, the events are:
( in at/intake/comp/power/exhaust/Effective-overlap/Ica)
@-4*/268/108/112/276/32/72.....142/104
@+0*/268/112/108/276/40/68....148/113
@+4*/268/116/104/276/40/64....155/123
@+8*/268/120/100/276/32/60....161/132


Notice the 4* increasing march in the compression degrees, and
the 4* decreasing march in the power duration. These two on this cam, always add up to the 220(in blue), and are fixed in this relationship by the intake/exhaust/overlap.
Notice also the changes in Effective overlap(in red). Overlap is the time at near TDC when both valves are open, the intake is opening while the exhaust is closing. In this cam, the overlap by the math is 44*. But when you install it, about half goes to each side (split overlap), so the Effective overlap COULD be 44* .. But when you install it at some position other than split overlap, then the Effective overlap is less than 44*, namely, it is double the smallest number. Split overlap for this cam would be, in at 112*LSA.
If you don't know how overlap works, see note-1

Now, lets see what happens to the predicted cylinder pressures, at sealevel in the 9.61Scr 340 . Check out the final two columns which are pressure and VP. Notice the approximately increasing 6psi march in pressure. But also notice the more rapidly increasing march in VP. The VP is what you feel , from idle to stall, perhaps to as high as 3500rpm. Small numbers indicate small performance. Big numbers point to big performance.
For comparison to your favorite stock engines; the slanty makes a VP of around 87, the 273 around 100, the Smoggerteen is about 116, the 360 was about 126, the 318M is about 129, and the 10.5-340 comes in around 137.... by the numbers.
So then, as can be seen, the VP numbers that you need to target with a manual trans are about 130 or more. But with an automatic, you can get away with less, if you increase your stall-rpm. Personally, I feel that my combo with a VP over 159(at sealevel) is waaaay overkill..... but it is soooo much fun.

But back to the chart; look what happens to the Effective overlap, when you advance thechit out of this cam. You get the pressure, and the VP, but lose overlap big-time. Furthermore, the power extraction is down to 100* so the engine is leaving a lot of energy in the exhaust, energy that could have been used to propel the vehicle. This translates to excessive fuel consumption...........
Also; the high pressure translates to what makes the engine throttle response snappy around town, allowing you to run a bigger carb without the low-rpm sluggishness that often accompanies that choice.

Ok, gotta go to work, so EDIT; this was only half-finished at 7.30 this morning,lol.

note-1
O
verlap is the Fifth Cycle, and works almost exclusively with headers. What happens in the Fifth Cycle, is that the headers by their design, "yank" on the intake plenum during this time by the fact that the plenum is connected to the exhaust system during overlap. Log-manifolds to NOT pull on the intake. This yank/tug/ negative pressure; whatever you want to call it, gets the A/F mixture moving from the plenum, down the runners, and hopefully into the chambers, SOONER than is possible without overlap, and so begins the cylinder-filling process, sooner. The more overlap you have, the higher up into the rpm operating range, this process can continue. So for power production, the more overlap you have, the more power you will make while this process is in full swing. And this is no minor process.

By the way the cam is ground, a given set of lobes will, by way of the Fifth Cycle and headers, make more power the tighter you LSA them, ....... at the expense of Powerband. Therefore, you can tune a given cam to suit your trans or your weight, etc, by fudging with the LSA.
The A999/A500 have gearsplits of .56/.65
The A904/A727 have gearsplits of .59/.69
The A833 , ....has splits averaging .735
The GVod operating as a splitter, has splits averaging .79 thru the first two gears of the Commando box.

So as you can see, each of these transmissions has a different powerband requirement; the autos have only three gears to the A833s 4 gears; so naturally the powerband will need to be wider for it.................. right up until you install a very-high stall TC. For instance; if you shift at 6000 with a 4500TC, then your powerband requirement is just 1500 rpm or 4500/6000= .75, Aha!.
Again this great info, thank you Mr. Wizard.
I asked Jim today at RB to target 160 CCP for my new cam , he running the numbers.
So given that this engine will be driving a A727 with a 3000 stall lock up converter shifting @ 6000 rpm what would be the recommended LSA?
 
Is look at a108/106 but how rowdy do you want the idle and do you visit the top end a bunch?
This is a street car, I would like it to idle. I drive it a fair amount some highway some slow speed.
I do like to get on it, perhaps I will have it ground on a 107?
 
What rear gear? was it 3.55s?
what weight again? Was it 3000 with you in it?
what size tires?
For the short answer, scroll to the bottom,lol.

Given a 3.315 stroke and 9.61Scr, with a 3000stall, even a lock-up; the fuel mileage will be lousy with even a modest cam. In which case, you can bias the combo towards performance, and drive the 2liter grocery-getter for mileage.
However, I don't think it would be prudent to recommend an LSA until you have decided more about the cam, ................ because, as we have seen, the pressure moves around an awful big bunch.
And pressure is power.
While the 3000TC is forgiving of less pressure, I still don't think that's a good reason to abandon it, because that same pressure works from stall to shift-rpm in a similar but different way.
That 3000 stall comes in a tricky place. Your ignition timing is often or can often be, a challenge to engineer, between 2500 and 3500.
In Second gear, at zero-slip that is from 38 to 54 mph, with 3.55s and 27" tires. So that is a big window, and you will spend a lotta time in there with a streeter. So, that kindof points to being careful with the pressure in there, or being conservative on the timing in that zone. A lot of guys will crank the timing in early, often 36/38 degrees with iron heads, and in as early as 2500. IMO, that is usually a mistake, but they get away with it because most guys don't push the pressure limit, and will slam a hi-stall into it. Plus with a short-stroke 340, you can get away with more chit, that you cannot, with a longer stroke.
Furthermore, your cooling system will play a huge roll in all of this. IMO, you cannot tune an engine running on the edge, if you cannot control the temperature precisely. So like with an electric system cycling on/off between two set points often 10 to 20 degrees apart, you are just asking for trouble. Don't even go try to tune that. Your operating temp, needs to be rock solidly controlled to a very small window.
I chose a set point the gets me 205 to 207 degrees at a particular reference point on the intake, just below the Stathouse, as measured by an IR gun. Additionally, my carb runs on air that it get from atop the hood. And that atmospheric air runs between 60 and 90 at most so, again, a small window, as compared to say 60 and 200 with underhood air. So the bottom line is I get a happy engine, that I can build a curve for, that most guys or at least a lotta guys can only dream of. And so, I get performance numbers that some guys on FABO I'm pretty sure they find them questionable at the least. One guy said my results were impossible. One guy didn't flat-out call me a liar but I bet he was thinking it...
Anyway the point is that pressure and heat are power. But when you desire to push the limit on the street,with iron heads, it often leads to a combo, that has to be re-engineered due to problems with detonation. Which sorta sucks.
It has been said many many times, by way smarter guys than me, that you will lose more power by not being able to run full timing, than by simply dialing back the pressure.
Besides, you are building more of a cruiser; am I right? Allbeit with some hi-flow heads. So by putting the power in the heads where it belongs, You can sacrifice a bit of, both, pressure and rpm; to get some driveability.
With 3.55s you have already pushed your operating roadspeed up some, IMO a lil high for this combo. Earlier, you were thinking of a 224 cam , but the switch to a solid on a tighter LSA, will allow an easy 230* for the same pressures. So, a 230 cam will peak around 5200 in a 340, and depending on the LSA will allow a shift-rpm of about 200 to 500 rpm later. The 108 will drop off pretty fast, so lets call it 200 and therefore an optimum shift rpm of 5400. With 3.55s, and 10% slip at WOT, this 5200rpm powerpeak occurs at 43mph in First, and 73 in Second. The 1-2 shift split with a standard TF is 59% so shifting at 5400, the Rs will fall to 3200, and your 3000TC is just right for street. But it's still a long climb from 43mph to 73 some of it in a low-power zone created by the 108LSA.
See, the 108 creates more power, but it does it with rpm, and sacrifices a lil on the way there. So with a power peak at 5200, you can expect a torque peak at around 3700, which in Second gear is 52 mph. So from 43 to 52, the 108 cam is struggling a tad. When it gets into the meat of the curve, it will blast thru there, and you'll really feel it. Not like a 114 which is more like a tractor.
There is a very good reason why most modern cams are supplied on 110s, they just work and are very street-friendly. You can throw almost any timing curve on them, and just drive them. But every guy in town has one so when you line up, you got no surprises for the other guy.
So, while the 108 does have the potential to make more absolute power,
the question is, on the street will it be better than the more typical 110s? Because of the "speed limit" and just the two gears to 80 mph, I don't think you will see it in the ET. First gear you will just burn thru. So the race starts in Second at 43=3200 and ends at 65=4330, almost 900 rpm from the powerpeak, and perhaps 600 after the torque peak. I think you could be quicker with less LSA, and quicker with a smaller cam spooled up with say 3.91s or 4.10s.. For example, 3.91s would get you 65=5100@10% slip. This would allow a power peak of say 4800 with a 110LSA cam. And that looks like it could be a 220@.050 cam. The absolute power would be lower, but the average power between 43 and 65mph could be nearly as much, and the ET could be very similar. For a streeter, more is not always better.

With your lightweight car and 3000TC, I would want to give the 108 a try, for sure, but it sorta depends on the rest of the cam, and the combo.

One thing I forgot to mention; the 108 cam, in these sizes, has lots of power-extraction, to boost your mpgs. All you gotta do is run the Cruise rpm high enough to keep the engine out of reversion, which with a 230/110 cam is about 2200; so you got that covered with the 3.55s; 2200 is about 52mph, so you might consider that your minimum Cruising speed, lol.
 
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What rear gear? was it 3.55s?
what weight again? Was it 3000 with you in it?
what size tires?
For the short answer, scroll to the bottom,lol.

Given a 3.315 stroke and 9.61Scr, with a 3000stall, even a lock-up; the fuel mileage will be lousy with even a modest cam. In which case, you can bias the combo towards performance, and drive the 2liter grocery-getter for mileage.
However, I don't think it would be prudent to recommend an LSA until you have decided more about the cam, ................ because, as we have seen, the pressure moves around an awful big bunch.
And pressure is power.
While the 3000TC is forgiving of less pressure, I still don't think that's a good reason to abandon it, because that same pressure works from stall to shift-rpm in a similar but different way.
That 3000 stall comes in a tricky place. Your ignition timing is often or can often be, a challenge to engineer, between 2500 and 3500.
In Second gear, at zero-slip that is from 38 to 54 mph, with 3.55s and 27" tires. So that is a big window, and you will spend a lotta time in there with a streeter. So, that kindof points to being careful with the pressure in there, or being conservative on the timing in that zone. A lot of guys will crank the timing in early, often 36/38 degrees with iron heads, and in as early as 2500. IMO, that is usually a mistake, but they get away with it because most guys don't push the pressure limit, and will slam a hi-stall into it. Plus with a short-stroke 340, you can get away with more chit, that you cannot, with a longer stroke.
Furthermore, your cooling system will play a huge roll in all of this. IMO, you cannot tune an engine running on the edge, if you cannot control the temperature precisely. So like with an electric system cycling on/off between two set points often 10 to 20 degrees apart, you are just asking for trouble. Don't even go try to tune that. Your operating temp, needs to be rock solidly controlled to a very small window.
I chose a set point the gets me 205 to 207 degrees at a particular reference point on the intake, just below the Stathouse, as measured by an IR gun. Additionally, my carb runs on air that it get from atop the hood. And that atmospheric air runs between 60 and 90 at most so, again, a small window, as compared to say 60 and 200 with underhood air. So the bottom line is I get a happy engine, that I can build a curve for, that most guys or at least a lotta guys can only dream of. And so, I get performance numbers that some guys on FABO I'm pretty sure they find them questionable at the least. One guy said my results were impossible. One guy didn't flat-out call me a liar but I bet he was thinking it...
Anyway the point is that pressure and heat are power. But when you desire to push the limit on the street,with iron heads, it often leads to a combo, that has to be re-engineered due to problems with detonation. Which sorta sucks.
It has been said many many times, by way smarter guys than me, that you will lose more power by not being able to run full timing, than by simply dialing back the pressure.
Besides, you are building more of a cruiser; am I right? Allbeit with some hi-flow heads. So by putting the power in the heads where it belongs, You can sacrifice a bit of, both, pressure and rpm; to get some driveability.
With 3.55s you have already pushed your operating roadspeed up some, IMO a lil high for this combo. Earlier, you were thinking of a 224 cam , but the switch to a solid on a tighter LSA, will allow an easy 230* for the same pressures. So, a 230 cam will peak around 5200 in a 340, and depending on the LSA will allow a shift-rpm of about 200 to 500 rpm later. The 108 will drop off pretty fast, so lets call it 200 and therefore an optimum shift rpm of 5400. With 3.55s, and 10% slip at WOT, this 5200rpm powerpeak occurs at 43mph in First, and 73 in Second. The 1-2 shift split with a standard TF is 59% so shifting at 5400, the Rs will fall to 3200, and your 3000TC is just right for street. But it's still a long climb from 43mph to 73 some of it in a low-power zone created by the 108LSA.
See, the 108 creates more power, but it does it with rpm, and sacrifices a lil on the way there. So with a power peak at 5200, you can expect a torque peak at around 3700, which in Second gear is 52 mph. So from 43 to 52, the 108 cam is struggling a tad. When it gets into the meat of the curve, it will blast thru there, and you'll really feel it. Not like a 114 which is more like a tractor.
There is a very good reason why most modern cams are supplied on 110s, they just work and are very street-friendly. You can throw almost any timing curve on them, and just drive them. But every guy in town has one so when you line up, you got no surprises for the other guy.
So, while the 108 does have the potential to make more absolute power,
the question is, on the street will it be better than the more typical 110s? Because of the "speed limit" and just the two gears to 80 mph, I don't think you will see it in the ET. First gear you will just burn thru. So the race starts in Second at 43=3200 and ends at 65=4330, almost 900 rpm from the powerpeak, and perhaps 600 after the torque peak. I think you could be quicker with less LSA, and quicker with a smaller cam spooled up with say 3.91s or 4.10s.. For example, 3.91s would get you 65=5100@10% slip. This would allow a power peak of say 4800 with a 110LSA cam. And that looks like it could be a 220@.050 cam. The absolute power would be lower, but the average power between 43 and 65mph could be nearly as much, and the ET could be very similar. For a streeter, more is not always better.

With your lightweight car and 3000TC, I would want to give the 108 a try, for sure, but it sorta depends on the rest of the cam, and the combo.

One thing I forgot to mention; the 108 cam, in these sizes, has lots of power-extraction, to boost your mpgs. All you gotta do is run the Cruise rpm high enough to keep the engine out of reversion, which with a 230/110 cam is about 2200; so you got that covered with the 3.55s; 2200 is about 52mph, so you might consider that your minimum Cruising speed, lol.
Wow , just what I was needing.
Yes - 3.55 gearing on a 28 inch tire
3125lb's with me in the car
My thoughts at this time lean toward a single pattern 220@.50, .500ish lift ground on a 108 LSA with valve timing events that will trap 150-160 CCP
We will see what Jim at RB comes up with.
 
But ok lets do it!

The given will be a 340 cuber at 9.61 Scr; and lets stick to a known cam, the Mopar 340cam, that everyone so loves.
the specs are;
268 intake duration/ 276 exhaust duration/ ground on a 114LSA.
This cam has advertised overlap of 44*, and therefore the duration left for compression plus power is;
(360 x2+44) less (268+276) = 220* , which is a reasonably good number.
Lets install it at "straight up, and 4* in either direction, plus 8* advanced. So, the events are:
( in at/intake/comp/power/exhaust/Effective-overlap/Ica)
@-4*/268/108/112/276/32/72.....142/104
@+0*/268/112/108/276/40/68....148/113
@+4*/268/116/104/276/40/64....155/123
@+8*/268/120/100/276/32/60....161/132


Notice the 4* increasing march in the compression degrees, and
the 4* decreasing march in the power duration. These two on this cam, always add up to the 220(in blue), and are fixed in this relationship by the intake/exhaust/overlap.
Notice also the changes in Effective overlap(in red). Overlap is the time at near TDC when both valves are open, the intake is opening while the exhaust is closing. In this cam, the overlap by the math is 44*. But when you install it, about half goes to each side (split overlap), so the Effective overlap COULD be 44* .. But when you install it at some position other than split overlap, then the Effective overlap is less than 44*, namely, it is double the smallest number. Split overlap for this cam would be, in at 112*LSA.
If you don't know how overlap works, see note-1

Now, lets see what happens to the predicted cylinder pressures, at sealevel in the 9.61Scr 340 . Check out the final two columns which are pressure and VP. Notice the approximately increasing 6psi march in pressure. But also notice the more rapidly increasing march in VP. The VP is what you feel , from idle to stall, perhaps to as high as 3500rpm. Small numbers indicate small performance. Big numbers point to big performance.
For comparison to your favorite stock engines; the slanty makes a VP of around 87, the 273 around 100, the Smoggerteen is about 116, the 360 was about 126, the 318M is about 129, and the 10.5-340 comes in around 137.... by the numbers.
So then, as can be seen, the VP numbers that you need to target with a manual trans are about 130 or more. But with an automatic, you can get away with less, if you increase your stall-rpm. Personally, I feel that my combo with a VP over 159(at sealevel) is waaaay overkill..... but it is soooo much fun.

But back to the chart; look what happens to the Effective overlap, when you advance thechit out of this cam. You get the pressure, and the VP, but lose overlap big-time. Furthermore, the power extraction is down to 100* so the engine is leaving a lot of energy in the exhaust, energy that could have been used to propel the vehicle. This translates to excessive fuel consumption...........
Also; the high pressure translates to what makes the engine throttle response snappy around town, allowing you to run a bigger carb without the low-rpm sluggishness that often accompanies that choice.

Ok, gotta go to work, so EDIT; this was only half-finished at 7.30 this morning,lol.

note-1
O
verlap is the Fifth Cycle, and works almost exclusively with headers. What happens in the Fifth Cycle, is that the headers by their design, "yank" on the intake plenum during this time by the fact that the plenum is connected to the exhaust system during overlap. Log-manifolds to NOT pull on the intake. This yank/tug/ negative pressure; whatever you want to call it, gets the A/F mixture moving from the plenum, down the runners, and hopefully into the chambers, SOONER than is possible without overlap, and so begins the cylinder-filling process, sooner. The more overlap you have, the higher up into the rpm operating range, this process can continue. So for power production, the more overlap you have, the more power you will make while this process is in full swing. And this is no minor process.

By the way the cam is ground, a given set of lobes will, by way of the Fifth Cycle and headers, make more power the tighter you LSA them, ....... at the expense of Powerband. Therefore, you can tune a given cam to suit your trans or your weight, etc, by fudging with the LSA.
The A999/A500 have gearsplits of .56/.65
The A904/A727 have gearsplits of .59/.69
The A833 , ....has splits averaging .735
The GVod operating as a splitter, has splits averaging .79 thru the first two gears of the Commando box.

So as you can see, each of these transmissions has a different powerband requirement; the autos have only three gears to the A833s 4 gears; so naturally the powerband will need to be wider for it.................. right up until you install a very-high stall TC. For instance; if you shift at 6000 with a 4500TC, then your powerband requirement is just 1500 rpm or 4500/6000= .75, Aha!.
Hi all,
No hi jack.
But With this AJ post I'm curious
About where to Install this cam in a bbc
That only has about 8.5 -1 compression
Trying to give it as much bottom end as possible.
Howard's says install 4 * advanced or
4 * retarded on the cam card.
So with it already having 4 * advance
Ground in are they saying another 4 *
Plus or minus?
With the 112 Lsa,
Screenshot_20210730-174936.png

Screenshot_20210730-174956.png
I'm thinking 8 * advance in at 104?
Ps. I'm asking here because I don't belong to any chevy web. Sites...lol
Thanks in advance...no pun...
Btw. This is a hydraulic roller in a 468 ci.
if that makes a difference...
 
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Hi all,
No hi jack.
But With this AJ post I'm curious
About where to Install this cam in a bbc
That only has about 8.5 -1 compression
Trying to give it as much bottom end as possible.
Howard's says install 4 * advanced or
4 * retarded on the cam card.
So with it already having 4 * advance
Ground in are they saying another 4 *
Plus or minus?
With the 112 Lsa,View attachment 1715776494
View attachment 1715776495 I'm thinking 8 * advance in at 104?
Ps. I'm asking here because I don't belong to any chevy web. Sites...lol
Thanks in advance...no pun...
Btw. This is a hydraulic roller in a 468 ci.
if that makes a difference...
468 inches and 227deg @050 your gonna make plenty of torque. I’d be willing to stab it in on split overlap and at least try it how Howards designed it. Then advance it if it feels soggy. I bet it won’t.
 
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