split cam and cam suggestion

[Grumpy]

Hi! JEB from FINLAND,
I´m building 1973 454 engine from impala. Got 049/ oval port open chamber heads with stock valves. So my question is how much dome i need in piston and how aggerssive cam i can use to get all out from those stock heads? bore is 4.280 stroke is stock 4" and rods are stock too.
I was thinking COMP Cams Magnum Hydraulic Cam and Lifter Kits K11-208-3 - Free Shipping on Orders Over $99 at Summit Racing is that any good? Looks good packet with sprins etc.?
Ps. Sorry my bad english.
Looking something 10:1 compression.. cam should be good with street/strip. Little rough idle would be nice

what is split cam? I hear that my heads cant handle too aggressive cam with out bigger valves and some porting witch i dont want to do.[/quote]
valve seat and back face angles ,valve diameter and valve lift and duration effect the flow thru the curtain area

keep in mind that valve may be forced off its seat, too full lift and re-seating 50 plus TIMES A SECOND at near 5500 rpm, so theres very little TIME for gases to move through the very restrictive space between the valve seat and valve edge

Calculating the valve curtain area
The following equation mathematically defines the available flow area for any given valve diameter and lift value:
Area = valve diameter x 0.98 x 3.14 x valve lift
Where 3.14 = pi (π)
For a typical 2.02-inch intake valve at .500-inch lift, it calculates as follows:
Area = 2.02 x 0.98 x 3.14 x 0.500 = 3.107 square inches

split cam= different intake and exhaust lobe duration's and possibly lift specs.

write a list of all factors that will influence the cam selection choice, CALL AT LEAST 6-9 DIFFERENT CAM MANUFACTURERS, 7-9 WILL BE EVEN BETTER!,
DON,T LIE tell them EXACTLY what you expect and what you have currently ,installed,
and that the cam must work with NOW, NOT what you intend to install later.
DO NOT DISCUSS IN ANY WAY WHAT ANY OTHER MANUFACTURER SUGGESTED,
OR THAT YOU'VE EVEN TALKED TO ANY OTHER MANUFACTURER
YES you NEED too KNOW your COMPRESSION RATIO, and all the other answers to the questions below BEFORE calling....knowing a few more things, than your want a lope in the engines idle and you want a fast car when your done, about your combo , like your static compression ratio, displacement, cylinder heads used, rocker ratio, max valve spring clearance, or coil bind, height, spring load rates, carb,size, if its a vacuum or manual secondary carb, intake manifold,(single or dual plane,) headers, dimensions, your car weight, tire diam., do you need to pass emission testing? are you racing the car or is it daily transportation,etc would sure help, in the cam selection process??
selecting a cam without knowing those factors, is rather like marrying a girl based only on the color of her hair brush, you might make a good match but the odds say your dreaming
car weigh?
rear gear ratio?
tire diam.
trans and gear ratios?
stall speed if its an auto?
displacement?
COMPRESSION RATIO
HEADS (flow numbers)(lift restrictions)
intake type
tire size
intended use
max rpms
launch rpms
MIMIMUM IDLE
fuel octane
carbs,mpfi? CFM
ETC.
knowing a few more things, than you want a lope/ rumble in the engines idle sound , and you want a fast car when your done, about your combo , like your static compression ratio, displacement, cylinder heads used, rocker ratio, max valve spring clearance, or coil bind, height, spring load rates, carb,size, if its a vacuum or manual secondary carb, intake manifold,(single or dual plane,) headers, dimensions, your car weight, tire diam., do you need to pass emission testing? are you racing the car or is it daily transportation,etc would sure help??
selecting a cam without knowing those factors is rather like marrying a girl based on the color of her hair brush, you might make a good match but the odds say your dreaming
AVERAGE the RESULTS FROM EACH manufacturers suggestion,as to lift, duration and LCA and buy the cam thats the closest match to that average
this is generally a good street/strip cam in a 10:1 454,
but obviously calling several cam manufacturers would be a good idea
BBC 454 to 470 CID ?Old School? OEM 049/781 heads to a max of 5700 RPM - hydraulic roller camClay Smith Cams
or
Bootlegger Hydraulic Flat Tappet Cam - Chevrolet Big Block 277/304 - Lunati Power

CRANE
http://www.cranecams.com/uploads/lobe/masterlisting.pdf

CROWER
Crower master catalog for high performance engine parts

ISKY
Page Not Found - Isky Racing Cams

claysmith
Camshafts - Clay Smith Cams

engle cams
http://www.englecams.com/downloads/2010 ... atalog.pdf

elgin cams
http://catalog.elginind.com/app/engine_ ... by+Part+No.

herbert cams
Buy Performance, Comp, Roller Cams Online

howard
http://www.howardscams.com/howards2015.pdf

lunati
Cams - Lunati Power

almost every mechanics tool box needs a few basic measuring tools and supplies

https://www.amazon.com/Claytoon-Set...d=1466872286&sr=8-17&keywords=plastilina+clay

http://www.utrechtart.com/Plastalin...currency=USD&gclid=CN3G75zOw80CFQgaaQodKbgFjA

 

[Grumpy]

[ quotee=isky cams posted this]

Longer Exhaust Duration: Is this really necessary?

Most stock camshafts from American production V8, V6 and 4 cylinder engines manufactured today are ground with the longer exhaust lobe duration. Or, another way of looking at this is that they are ground with shorter intake durations! The former embraces the viewpoint that either the Exhaust Ports or Exhaust Pipe system is somewhat restrictive, and is in need of an assist. The latter suggests that the intake system is rather efficient and cam timing can be trimmed back a bit with out much sacrifice in power, in order to maximize throttle response and cruising efficiency.

Take your pick here. There is no absolutely correct viewpoint - because both are probably true! In a stock engine running at conservative RPM levels, for the sake of overall efficiency, fuel economy and a quiet smooth running engine, this staggering of intake and exhaust duration is quite common and appropriate.

However, High Performance is another thing entirely. Change one factor, let's say in this case, the exhaust system (installing headers and larger pipes) and you have just negated in most cases, the need for that longer exhaust lobe. Now couple this change with a different intake system and camshaft and you have really scrambled the equation. But, wait just a moment. Why is it that so many people (racers & cam grinders alike) insist on running a cam with longer exhaust duration regardless of what equipment is employed? The answer is "habit". Most of them have been somewhat successful in doing it their way and will probably never change unless virtually forced by circumstances to do so.

Before we go any further however let's review what it actually is we are trying to do with an engine when we attempt to make more power. Our best result comes when we are cognizant of the fact that an engine is basically an air pump. We pump it in and out (although in a different form) and we have problems when one side or the other is restricted. Balance or the equilibrium or flow should be our objective, unless of course we are not trying to make more horsepower!

Example #1 (Oval track racing) Here, I have often observed that the most experienced drivers are those who are most likely to run a single pattern (equal on intake and exhaust duration) cam. Why? Because such cams always, I repeat always make more torque! These veterans have a more educated foot and greater experience in feathering the throttle in the corners. They can therefore, utilize the benefit of added torque, in the lower to mid RPM range, to their advantage.

Their counterparts, the younger drivers on the circuit, generally are not as experienced and may at times actually get "crossed up" in the corners especially with a lighter car or when they are learning the ropes. In their case, a longer exhaust duration is often the more appropriate choice. It will often help them to drive better, more "flat footed" if you will, without consequence. But please for the sake of accuracy, let us be truthful. The benefit comes from an actual bleeding off of low to mid range torque, which is always what happens when Exh. Duration is lengthened, not from any improvement. The improvement, (if any) would come because of an improvement in scavenging at the extreme upper end of the power curve and would usually be marginal at best. Yet the so-called "extra power" potential of a longer Exh. Duration cam is most often why they are touted - power most people are backing away from at the end of the strait away!

Example #2 (Drag Racing) At the drag strip it's a little different and I feel more honest. Here, racers have long enjoyed longer exhaust and longer durations across the board (If I may add specifically for the purpose of "killing" low-end torque) to keep the tires from too easily breaking lose. This has been successful and sometimes actually results in a slight increase in top end power - something you can actually use in drag racing since it is a full throttle endeavor through the lights. Keep in mind here though, it's quite possible that a longer duration cam overall would have done just as well or better. In other words if you needed that longer exhaust for top end, perhaps the intake could have benefited from such a lengthening as well.

One of my favorite expressions is how "The Drag Racing mentality has infiltrated the ranks of Oval Track". Many have crossed over and made the switch in the past 10-15 years and some have brought their preconceived notions about how to cam an engine with them. A few may actually read these concepts and if they do so will at least come away with a better understanding of what they are doing. On the other hand they also could find that this information might actually help their cars to run just a bit faster!

Note: Readers may find Camfather Ed Iskenderian's Top Tuners Tip #33 "Can an Exhaust System Over-Scavenge the Combustion Chambers" to be a relevant precursor.

- See more at: http://www.iskycams.com/tech-tips-2000.html#2003[/quote]

http://victorylibrary.com/mopar/cam-tech-c.htm

 

[87vette81big]

I like Reading Ed Iskenderian & Ron Iskenderian & Harvey Crane Tech Articles Grumpy.