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cam changes
https://slantsix.org/forum/viewtopic.php?t=53671		 Page 1 of 2
Author:  Romeo Furio [ Wed Oct 23, 2013 3:58 pm ]
Post subject:  cam changes
So I'm putting together a street/strip 64 Dart together with a bunch of leftover parts that I have laying around.
The engine I have is a stock bore and piston 67 225 with a head milled .100 and mild port work,stock valve size.Clifford intake and a 500 AFB.Clifford shorty headers.
The cam is a Comp part#64-000-5 Grind#cr6 5667/5668 s 108+4
Lift .424 I&E Duration at .050 I 230 E 238
Lobe separation 108
So it has a 4 degree advance built in. I'm thinking of changing the degreeing and have heard that some of you like to retard several degrees. This car will be about about 5 to 600 pounds lighter than the (67 Dart 3200+ lbs) the engine was in.
I'm also planning on running 2.94 gears to a maximum of 3.55's.Most likely will run the 2.94's because everything is high speed highways around here.Average speeds between 65 to 80 mph just to keep up with traffic.The car will have a Hughes locking converter with a stall of 2200 rpm.
Any thoughts on which way to go or leave the cam the way it is.??
Author:  Doc [ Wed Oct 23, 2013 4:12 pm ]
Post subject: 
Does the cam card define the Intake Valve closing point? (IC)
With the IC number we can calculate the DCRs at different cam advance / retard positions.
DD
Author:  Romeo Furio [ Wed Oct 23, 2013 4:32 pm ]
Post subject: 
Thanks Doc, Here ya go,,,
Valve timing Open Close
At .050 I 11 BTDC 39 ABDC
E 51 BBOC 7 ATOC
Author:  Romeo Furio [ Wed Oct 23, 2013 4:33 pm ]
Post subject: 
Sorry if hard to read, It didn't post the way I typed it.
Author:  Doc [ Wed Oct 23, 2013 5:05 pm ]
Post subject: 
The 39 IC is the important piece of the puzzle.
The other "unknowns ar the actual hed cc's (45?) and the block deck. (-180?)

With those estimates and a .020 head gasket, the static cr is 9.2 and the DCR is 7.92

Confirm the head cc's and deck so you can dial-in the DCR with that cam.
Doug
Author:  Romeo Furio [ Wed Oct 23, 2013 6:13 pm ]
Post subject: 
The head cc'd at 44. The head gasket .039 Block has the factory deck height as the short block has never been apart.
Author:  Sam Powell [ Thu Oct 24, 2013 4:31 am ]
Post subject: 
You guys sure impress me with your smarts. That is not a smart-a** comment. I mean it.

Sam
Author:  Romeo Furio [ Thu Oct 24, 2013 7:41 am ]
Post subject: 
Sam, I'm dumber than a doughnut when it comes to numbers. Just reading what I found in the file from when I first started working on the 67 about 20 years ago. The engine was modified around '96 to keep up with the drivers on the Hot Rod Power Tour. It's been sitting in the corner for the last 10 years. So I thought to call the Dart "Leftovers". We will see how it turns out.
Author:  Doc [ Thu Oct 24, 2013 9:09 am ]
Post subject: 
So the deck height is the big unknown here...
("Stock" does not mean much seeing the factory was "all over the map" with this number)

Cut to the chase....
Measure the deck and set that at -.160 (may need a "clean-up" cut)
Set that cam so the IC is 54 ABDC. (Straight-up) Check the IC at .016 lash.
Doing that will get you a 9.3 CR and a 8.015 DCR.
DD
Author:  Romeo Furio [ Thu Oct 24, 2013 3:29 pm ]
Post subject: 
O KEY DOO KEY ! Thanks
Author:  Sam Powell [ Sun Oct 27, 2013 6:10 am ]
Post subject: 
Is the difference between compression ratio and dynamic compression ratio result from the losses at overlap?

And a dummy question: What is ABDC.? Thanks. Sam
Author:  robertob [ Sun Oct 27, 2013 8:06 am ]
Post subject: 
Quote:
Is the difference between compression ratio and dynamic compression ratio result from the losses at overlap?

And a dummy question: What is ABDC.? Thanks. Sam

Dynamic compression ratio isn't really an accurate term but people use it anyway. What they really mean is 'Effective' static compression ratio, which is the compression ratio calculated from the point the intake valve closes on the compression stroke. So a big intake lobe, or one that is retarded, closes the intake valve as the piston is further up the cylinder. The later the valve closes the less effective compression the engine has.

That's why a big cam can use more compression without pinging on the same fuel.

Overlap could be more or less with the same DCR depending on how far apart the lobes are ground.

ABDC = After Bottom Dead Center (on the compression stroke).
Author:  Romeo Furio [ Sun Oct 27, 2013 2:43 pm ]
Post subject: 
I'm working on getting the deck height figure to finish the equation Doc has started.
Author:  Romeo Furio [ Wed Oct 30, 2013 6:52 am ]
Post subject: 
Doc you were correct as usual,this engine the deck height is .200 max and varies .004 between the 6 cylinders.As you said"All over the place".
As stated before just wondering if I should leave it as is or try retarding if it would make it run better.
I'm calling this car "Leftovers" :wink: as it is being put together with what I have that has been sitting around the shop and on shelves.She won't look like much but will be in great mechanical shape for MATS in April.
This will be my final slanter(maybe) for now.
Author:  Romeo Furio [ Sun Nov 03, 2013 6:28 am ]
Post subject:  Calling on Doc
Just a bump for Doug, Hope ya chime in and help me finish the puzzle with the last spec in the post above. :?:
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