My motor is NA, 565", 4.605" bore, 11.625" Deck, 10.1 cr.. merlin block, sheet metal intake, with 2x1000 cfm throttle bodies, EFI. I have my MSD locked out at 34*.. It starts great 99% of the time.. and doesnt kill that often. If I idle it down under 600rpm.. then it will. New computer for the EFI this year.. and it will be tied to a WB O2 sensor.. and I will be able to control the MSD 6A box with it.. Pretty excited about that.. Built it myself.. I presently have a Cutler system that tunes itself.. works, but not as good as I think it should... Some day I may take it to 650", but that costs and I am not sure what kind of an animal I would end up with..

Dick

Mr Gadets,I just ran some numbers on your combination using a crane #13R000190 cam w/solid roller lifters.I'm impressed,you do have IDLE TORQUE,especially around 1200 RPM.Are you using 18* or Big Chief heads,wall thickness and diameter push rods,belt drive,lifter bore bushings,lifter valley spray bar,35#flywheel ? Do you feel your sheet metal intake is super cooling the airflow, there by rejecting heat soak at engine shut down?

I am running an Ultradyne cam... 263/268 .686" lift.. solid roller.. Dart 320 heads with wedges, intake flow is about 380cfm.. not sure on the exhaust..
Thick wall 3/8" push rods... bushed lifter bores, steel flywheel.. not sure how heavy.. Regular old timing chain.. no spray bars. EFI doesnt seem to have a problem with the heat soak..

hope this helps..

The cam you pick, and how it's installed is going to affect the idle and possibly the startup of your motors. There are so many cam grinds out there. You should find people that built similar motors and see what cams they used and make a decision that will satisfy your application. I know that Comp cams is very friendly and may give you advise over the phone. Also I believe Msd has a device that you can back off timing when you start up and can bring it up after motor is running, saving wear and tear on your starter. Also if the motor runs cool enough, heat soak will be of minimal concern. Usually 20 degrees above normal operating temperature. Hope this helps < BBB

Big Block Billy,Those are good points,I agree,comp is good people,in fact they confirmed using 7/16 x .120 wall tapered push rods because of the harmonics they see in thinner wall while testing on their Spintron.The heavier push rod also serves to hold the lifter wheel on the cam a little bit better.Comp also sees further reduction in harmonics with a belt drive.I believe Daimer Elgin may have been the originator of the cam mentioned above.However,installed are,basically, merc 1075 cams,only opened up a little because of the cubic inch and 110*max PV.Thermal heat rejection (heat soak) is a lengthy subject.Shortened,Mr Gadgets has a sheet metal intake.A sheet metal intake can be designed with applied Bernelle's principle (Venturi) to cool the charge similar to an inter cooler.Therefore,subject to various influences, Heat Soak may be applicable.

Very interesting stuff indeed. If all of the top persons in whatever field they are in, be it doctors, engineers, motorbuilders, etc... got together as a group of thier kind, all of them would have learned something. No one has all of the knowlege there is except for God. I really love this site because it really helps people expand in knowledge if they really want to learn more. And most people on here want to help, which benefits all who listen ...BBB

Also the machine shop I use dosen't trust a cam card, in fact every motor they build, the cam goes on a cam doctor and is thoroughly checked and then used or rejected. They don't go by advertised duration , or .050 lift figures, they check each lobe and know what it really is, not what it is supposed to be ! Maybe it was Juan's or Leroy's or Tony Baloney's first day grinding a cam and it made it out the door !!! BBB

Ccando,
The heat of vaporization is a natural process that takes place when a liquid changes to a gas. Deceiving at first, by definition, it would be assumed that the transformation of liquid to a gas is creating heat. But quite the contrary. While the composition of the liquid is being changed to a gas energy is consumed in the form of heat. The area where the transformation takes place gives up heat to the transformation process and this heat is carried away by the newly formed gas. This is the law of physics that creates cooler charge air temperatures in carbureted engines when compared to dry-flow port fuel-injection systems. The conversion of the liquid fuel to a gas in the carburetor and intake manifold plenum pulls the heat from the manifold runners, effectively creating a substantial drop in charge temperatures. Credit: evans
Here are some links addressing Bernoulli’s principal as it relates to flow rates, cross sectional area, pressure, and velocity.
http://home.earthlink.net/~mmc1919/venturi.html
http://theory.uwinnipeg.ca/mod_tech/node68.html
Before I map this, I have some data that does not jibe with yours. On Dicks engine I calculate: (4.25” / 8”)
103.9*/76.1* PPV @ 7200.5 FPM @ 6250 RPM (within tolerance)
Yours I calc (4.75” / 6.625)
107.3*/72.7* PPV @ 7939.6 FPM @ 6000 RPM (the PPV is < 2.7*)
Bob

This is all taking me back to college days. Thought I had forgotten all that.

Rmbuilder,once again,you have provided a good amount of specific knowledge. As referenced about the aircraft wing,as velocity increases,pressure decreases AND temperature also decreases.Those three components are most influenced by parasitic drag. Parasitic drag is the little missed burr on the inside of the manifold or otherwise fancy port job on the heads. Incidentally,Rmbuilder's post also provides insight about the deck contour of some of the new boat hulls. Hydrodynamics does most of the work until the airfoil can reach takeoff speed,then the boat breaks loose and runs. Rmbuilder,I'm still looking for opinion on DETONATION vs. PRE IGNITION . I do agree with your numbers, but rounded, there remains a 5*spread in the two C/R Ratios.