PM sent Brother.
408 stroker build
- Thread starter dust-u
- Start date
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Fallible, as said by the creator himself. (IIRC) Still something good to start on. The crazy thing is you can sit down on computer talk to the best of the best, follow basic guidelines, you’re always gonna end up with a different cam. Everybody always has an idea what the best cam is, And while they are 100% right, they’re also at 100% wrong.
Rumble,
Crane contracted DV to test cams & he claims he did 10,000 tests, just at Crane alone. He also claims that in his lifetime [ I believe he is in his late 70s ], he has done 500,000 dyno pulls. From his testing came his Cam Program & the 128 rule was an abbreviated 'get you in the ball park' rule...rather than ringing a cam company & have someone read something off a computer screen.
When I find somebody that has done more cam testing than DV, I will listen to them. But in the meantime..........
Crane contracted DV to test cams & he claims he did 10,000 tests, just at Crane alone. He also claims that in his lifetime [ I believe he is in his late 70s ], he has done 500,000 dyno pulls. From his testing came his Cam Program & the 128 rule was an abbreviated 'get you in the ball park' rule...rather than ringing a cam company & have someone read something off a computer screen.
When I find somebody that has done more cam testing than DV, I will listen to them. But in the meantime..........
Right on Bewy.
The best thing you can do is take a deep dive (read) into those guys and other pioneering cam grinders. Work your way forward in the years. Ed Iskiderian (The Cam Father) Crane, Harold Brookshire, etc...
After reading a bunch of there stuff and testing a small bag of cams with very similar specs just for fun, I’ve come to a place where I find when your driving the street or running brackets, I am no so worried about the cam.
I’m not really thrilled in making a cam recommendation with the person asking “What’s the best absolute cam for my application because of a few factors of opinion and taste. Where I make one, the next poster offers there’s. It will be a good one as well and the difference is minute. On the street, you’ll never feel it. On the track, you MAY see it.
@dust-u, re ask your question.
The best thing you can do is take a deep dive (read) into those guys and other pioneering cam grinders. Work your way forward in the years. Ed Iskiderian (The Cam Father) Crane, Harold Brookshire, etc...
After reading a bunch of there stuff and testing a small bag of cams with very similar specs just for fun, I’ve come to a place where I find when your driving the street or running brackets, I am no so worried about the cam.
I’m not really thrilled in making a cam recommendation with the person asking “What’s the best absolute cam for my application because of a few factors of opinion and taste. Where I make one, the next poster offers there’s. It will be a good one as well and the difference is minute. On the street, you’ll never feel it. On the track, you MAY see it.
@dust-u, re ask your question.
yellow rose
Overnight Sensation
As Rumble said, get on the phone. Call 10 different grinders. The one you get on best with will almost always get you the best cam for YOUR application. You MUST be honest. Take notes. Email is worthless because it’s near impossible to have a conversation with email, although I did it a few weeks back and it worked out well. But the guy I was emailing was super pronto in his replies, and even replied after hours. He is a rare bird.
You can use the Vizard 128 method for getting an LSA. If you know how to use it. As your compression ratio goes up from about 10.5:1 you have to add one degree of LSA per point of compression IIRC. As you go lower than 10.5:1 you have to take away one degree of LSA.
The formula is volume of one cylinder divided by intake valve diameter times .91 and you take that number and subtract it from 128. Sooooooooo...
Just taking a 340 for an example...the volume of one cylinder is 42.5 cubic inches (for a standard bore). 42.5/2.02 is 22.376237*.91=20.362375. Then it’s 128-20.362375 and you get 107.63763 and you round that up to 108. I would run it at 107, but that’s me. And that’s IF you have about 10.5:1 compression.
If we use a 408 with a 2.02 valve you’d end up with 105. Which makes sense if you think about it. You’ve added displacement and the intake valve is the same diameter, so you need to get more overlap to get the cylinder filling.
What you don’t get into the cylinder at overlap you can’t make up later in the intake stroke.
Again...this is a pretty close approximation. You still have to figure duration.
You can use the Vizard 128 method for getting an LSA. If you know how to use it. As your compression ratio goes up from about 10.5:1 you have to add one degree of LSA per point of compression IIRC. As you go lower than 10.5:1 you have to take away one degree of LSA.
The formula is volume of one cylinder divided by intake valve diameter times .91 and you take that number and subtract it from 128. Sooooooooo...
Just taking a 340 for an example...the volume of one cylinder is 42.5 cubic inches (for a standard bore). 42.5/2.02 is 22.376237*.91=20.362375. Then it’s 128-20.362375 and you get 107.63763 and you round that up to 108. I would run it at 107, but that’s me. And that’s IF you have about 10.5:1 compression.
If we use a 408 with a 2.02 valve you’d end up with 105. Which makes sense if you think about it. You’ve added displacement and the intake valve is the same diameter, so you need to get more overlap to get the cylinder filling.
What you don’t get into the cylinder at overlap you can’t make up later in the intake stroke.
Again...this is a pretty close approximation. You still have to figure duration.
@yellow rose , thanks for going into that a little bit.
Funny how I have a 340 cammed with a 108 and my stroker going with a 106 without the need of the formula.... a little head work (the soft grey matter, not the heavy metal matter....) and I get there.
Funny how I have a 340 cammed with a 108 and my stroker going with a 106 without the need of the formula.... a little head work (the soft grey matter, not the heavy metal matter....) and I get there.
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