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Author Topic: Some geewhiz info for any other ruhtards running the B-cam.  (Read 1900 times)
David Claflin
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« on: March 17, 2017, 09:01:55 pm »

Like me 

I replied to Buddy's comment here
http://forums.corral.net/forums/5-0-5-8-engine-tech/2357930-most-power-b303.html

He then PM'd me, here's what he said. Just figured I'd share this....

Here's my thought on that. First and foremost the cylinder sees the restrictions in the intake and exhaust as a whole system. It only knows velocity and flow as it enters and exits the cylinder. The cylinder only knows these as a restriction relative to the cylinder displacement at the rpm or range. The heimholtz equations are valid, but, to me, they are only valid once all the other parameters have been optimized. To start off in the design with runner length thoughts and how they affect the valve events is not how I would do it.

Even in all of the ramcharger experiments, they never ever changed the cams. All of the optimization was done on an established longblock.

To me, the longblock is a very critical thing as a baseline. and that should only be constructed by looking at the flows and velocities. first

Building an intake manifold from scratch is another animal altogether, but thats not the intent of this.

Buddy

Quote:
Originally Posted by superirish
Doesn't intake runner length play a role in where the ICL is set?
Quote:
Originally Posted by buddy rawls
I would run the cam in the 107-110 intake CL region.
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1990 Red LX, 306, 80MM, ported gt40's, ported explorer upper accufab longtubes, 3" exhaust, 4.30's, 336/331
1985 LTD LX 347, 205 11R's, TFS-R, 90MMTB, MAC 1 3/4" longtubes, 4R70W, mach 1 brakes
1988 GT long term project
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« Reply #1 on: March 17, 2017, 09:36:46 pm »

Like anything, it's getting the combo where everything works together. Make one error and it becomes a dog. 4 Eyed
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71 Comet, 289,351w heads,RR's,12.5 TRWs,ported torker/750DP, Liberty Top Loader (2.78), 9"/6.00s, tubbed,ladder bars,11.9xs@110 ..bla,bla,bla
84Cougar,88HO,Eddy RPM/700DP, 1.7RRs, shorty's, 8.8/4.10s,T-5/Hurst Pro Billet, K/C clutch...bla,bla,bla

Never shoot your mouth off unless your brain is loaded.   If you're not laughing...you're not living!
Jeff351w
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393 build & new trans in progress


« Reply #2 on: March 18, 2017, 01:57:43 am »

Thanks for posting this David.  It's some information that I needed to be reminded of at exactly the right time.
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I often have tires with just too much tread or a fuel tank that is just too full. Accept no substitutes!
289nate
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« Reply #3 on: March 18, 2017, 01:16:37 pm »

Interesting.  Thanks for posting that David.  I also find it interesting that the cam will ideally want to be shifted north of 6,500 rpm which doesn't work well for a 6,000 rpm cam core and valvetrain.

Looks like you can make up for the B cam if you throw enough boost or spray at it.   Grin
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\'65 fastback pump gas 289, 4.56 gears, and faceplated T5.  11.123 at 122.4
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« Reply #4 on: March 18, 2017, 02:04:00 pm »

Its funny to read about the compression requirements of that cam.

My brother had a typical B cam car in the late 90s, ran high 12s on the motor. Blowed a head gasket on the bottle and decided to angle mill the heads while they were off. With the added compression, the car came alive. Eventually ran 12.20s N/A.
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Doing more with less, or something like that.
http://sbftech.com/index.php/topic,20009.0.html

Quote from: Monte Smith
Bottom line, if it was the hot ticket, the fast guys would do it.............they don't

You might need some Titanium rods and a flow bench!  LMAO on floor

I honestly don't get it.

I'm sweating, my heart is racing, my clutch foot is twichin', and my right arm punched the computer screen doing an involentary 2-3 shift while reading all that. 
David Claflin
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« Reply #5 on: March 18, 2017, 11:08:29 pm »

We'll see, if I can get this speed density set up to work I think the vic jr. with a 4 hole throttle body will run better than a ported Holley SMII
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1990 Red LX, 306, 80MM, ported gt40's, ported explorer upper accufab longtubes, 3" exhaust, 4.30's, 336/331
1985 LTD LX 347, 205 11R's, TFS-R, 90MMTB, MAC 1 3/4" longtubes, 4R70W, mach 1 brakes
1988 GT long term project
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