Thread: Blown 383 stroker cam selection

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At 10 lbs of boost with 8:1 static compression ratio, you're into race gas territory. Is that what you want?

The chart from Blower Drive Service shows that the most boost that can be used with 8:1 on pump gas is 8 lbs.
According to the calculator provided by Wallace Racing, using 8 lbs of boost and a cam with a 82* ABDC @ 0.004" tappet lift closing point would put the dynamic compression ratio at 8.6:1
Here is such a cam and the Wallace information. I used 20 ft. as your altitude.
http://www.cranecams.com/?show=brows...tType=camshaft
Your engine summary is as follows:
Bore - 4.03 inches
Stroke - 3.75 inches
Rod c-c length - 5.7 inches
With a static compression ratio of 8.0:1.
Your camshaft specifications call for an inlet valve closing of 82 degrees ABDC (after bottom dead center).
Your chamber volume is 111.98 cc's. With this camshaft your dynamic, or effective stroke is 2.45 inches.
Your dynamic compression ratio is 5.57 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 98.28 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 8 PSI is 8.60 :1.
http://www.wallaceracing.com/dynamic-cr.php

Use a tight squish (piston crown to underside of cylinder head at TDC) of 0.035" to 0.040" to prevent detonation. Initial advance at idle should be set at 16-24 degrees with the total advance of approximately 32-36 degrees, all in by 2500-3000 RPM. It is very important to verify the advance curve.

Recommendations from BDS:
http://www.blowerdriveservice.com/recommend.php

ALWAYS CONSULT WITH THE TECH PERSON AT YOUR FAVORITE CAM GRINDER FOR A RECOMMENDATION OF CAMSHAFT, LIFTERS AND SPRINGS BEFORE LAYING DOWN YOUR LONG GREEN. DON'T TAKE THE WORD OF AN OLD WORN-OUT GEARHEAD LIKE ME.

i used the cam below and it workes great

http://www.dougherbert.com/rollercam...cPath=83_84_90

i choose the small base circle cam to make sure everything cleared and used thes lifters also

http://www.dougherbert.com/rollerlifters-p-10095.html

the price from herberts is about half the price of anyone else...

i am running a 40 over 4 bolt small block , eagle crank and 5.7 rods ,srp blower pistons, dart pro 1 215 heads 72 cc, comes out about 8.1-1 ratio...
8-71 wieand with 2 750 demon blower carbs.
the car starts right away, has a great lopey idle, but will idle at 900 rpm in gear all day.

Originally Posted by 3rcfreak

i used the cam below and it workes great

http://www.dougherbert.com/rollercam...cPath=83_84_90

i choose the small base circle cam to make sure everything cleared and used thes lifters also

http://www.dougherbert.com/rollerlifters-p-10095.html

the price from herberts is about half the price of anyone else...

i am running a 40 over 4 bolt small block , eagle crank and 5.7 rods ,srp blower pistons, dart pro 1 215 heads 72 cc, comes out about 8.1-1 ratio...
8-71 wieand with 2 750 demon blower carbs.
the car starts right away, has a great lopey idle, but will idle at 900 rpm in gear all day.

Probable results of that cam in your motor.....
Your engine summary is as follows:
Bore - 4.03 inches
Stroke - 3.75 inches
Rod c-c length - 5.7 inches
With a static compression ratio of 8.0:1.
Your camshaft specifications call for an inlet valve closing of 85 degrees ABDC (after bottom dead center).
Your chamber volume is 111.98 cc's. With this camshaft your dynamic, or effective stroke is 2.35 inches.
Your dynamic compression ratio is 5.38 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 93.72 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 8 PSI is 8.31 :1

Hi Richard
Thanks for the info, just a few questions for you,

is the cam a good choice that i made for the engine, and how much boost could i put into the engine with pump gas,
i also have a methanol/water injection kit from snow performance that i will be adding also..
thanks lyndon

Originally Posted by techinspector1

Probable results of that cam in your motor.....
Your engine summary is as follows:
Bore - 4.03 inches
Stroke - 3.75 inches
Rod c-c length - 5.7 inches
With a static compression ratio of 8.0:1.
Your camshaft specifications call for an inlet valve closing of 85 degrees ABDC (after bottom dead center).
Your chamber volume is 111.98 cc's. With this camshaft your dynamic, or effective stroke is 2.35 inches.
Your dynamic compression ratio is 5.38 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 93.72 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 8 PSI is 8.31 :1

Richard,111.98 cc chamber volume?
How did you arrive at this number?

Originally Posted by erik erikson

Richard,111.98 cc chamber volume?
How did you arrive at this number?

I didn't, the calculator spit it out as a result of using the bore and stroke and static compression ratio to find the total compressed volume.

I'd like to hear your take on nitro's cam recommendation. I'm just going by the calculator and using 8 to 8 1/2 dcr. Should the dcr be different on a blown application as opposed to naturally aspirated????

Here are the results using a 64* ABDC closing point:
Your engine summary is as follows:
Bore - 4.03 inches
Stroke - 3.75 inches
Rod c-c length - 5.7 inches
With a static compression ratio of 8.0:1.
Your camshaft specifications call for an inlet valve closing of 64 degrees ABDC (after bottom dead center).
Your chamber volume is 111.98 cc's. With this camshaft your dynamic, or effective stroke is 2.95 inches.
Your dynamic compression ratio is 6.50 :1 corrected for cam timing, altitude, and rod length.
Your dynamic cranking pressure, corrected for cam timing, rod length and altitude is 121.02 PSI.
Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 8 PSI is 10.04 :1.