riski bidness

how much hp and torque should this combination produce.

4.530 bore bowtie block
4.250 stroke steel crank
9to1 compresion forged pistons
Intake 578 lift 311 duration
Exhaust 592 lift 316 duration
870 cfm carb holley
stock steel rectagulur heads
edelbrock air gap intake manifold

articfriends

iTrader: (1)

575-600 hp in marine trim,closer to 650 on the dyno with dry stepped tube dyno headers and no accessories,thats my guess. If you haven't bought cam yet consult with RMbuilder,he will ensure cam is optimum for your exact application,Smitty

SB

iTrader: (1)

No guesses. Interesting combo of parts. DO you have more cam specs or atleast cam man and part# ?

articfriends

iTrader: (1)

SB is right,without real complete specs the it is just a w.a.g,Smitty

riski bidness

cam is a crower hydraulic non roller

duunoit

iTrader: (1)

Did you mean 4.500 bore? I think that 4.530 would make it bigger than 540.

riski bidness

builder says 4.530

JimV

iTrader: (1)

That cam looks like it has too much duration. Whats the numbers @ .050?

SB

iTrader: (1)

I found it. I don't know if Crower does seat duration at .004" or .006" . Here is the info from http://www.crower.com/misc/cam_spec/...um=01245&prn=1 :

Crower Camshaft Specification Card
Part Number/Work Order Number 01245
Engine Application 396-454 CHEVY
Grind Number 311HDP
ADVERTISED CAMSHAFT SPECIFICATIONS:
INTAKE: Duration: 311º Lift: 0.578 Clearence Hot: 0
EXHAUST: Duration: 316º Lift: 0.592 Clearence Hot: 0
The specifications listed above are based on a rockerarm ratio of 1.7 IN
1.7 EX

RECOMMENDED VALVE SPRING INFORMATION:
Part # 68340 Single Dual X Triple
Approximate spring pressure: valve closed: 110/120 LBS.
valve open: 320/330 LBS.

The information below is for degreeing cam only. Correct only at .050" tappet lift.

INTAKE

Opens: 15.0 BTDC
Closes: 51.0 ABDC


EXHAUST

Opens: 61.0 BBDC
Closes: 9.0 ATDC


LOBE SEPERATION

112º


Duration at .050"

Intake: 246
Exhaust: 250


LOBE LIFT

Intake: 0.34
Exhaust: 0.348



If using "Lobe Center" method of degreeing, cam should be installed on an intake centerline of: 108º

rmbuilder

Riski Bidness,

Looking at the figures:
311º/316º Seat
246º/250º .050"
.340"/. 348" Lobe
.578"/. 592" Valve
65/66 Hydraulic Intensity

This is a textbook example in the inherent design limitations of flat tappet camshafts. Flats are velocity (rate of change of lift) limited vs. roller tappets, which are acceleration (rate of change of velocity) limited. The max velocity of the lifter varies according to (flat) tappet diameter, further compounding the issue for Chevrolets, with the smallest lifter diameter in the industry @ .842". The max velocity for a .842" lifter is 0.00714" (in/deg) per degree of rotation. By design, the only way to bring lift to the required values is to increase duration. With this comes the challenge of managing the byproducts of increased duration, one of which is overlap. This is the reason for the relatively modest lift value for this cam given the comparatively long seat and .050" values.

In contrast, a roller lifter is acceleration limited and velocity unlimited within the ability to control the mass of the valve train. The roller profile will yield significantly greater lift values with less seat and .050" duration figures and more importantly, greater lobe area. The reduced duration values may make the cam “look" smaller where actually it is not. Valves are opened “quicker/further/faster" providing more mid range and peak TQ.

In this application, if it is within your budget, a well-designed roller cam will provide significantly more performance, a more useable TQ/HP curve, in a more manageable package.

Bob