str8upchevy

I'm trying to figure out what the duration would be on my cam @ .050" (it's a custom grind cam)

You see I recently had a machine shop build me a small block 406, (long block) and when he was finished with it, I asked him for all the engine specifications including the "Cam Specs".

Well, all he could tell me about the cam was that it's a custom grind that he had made specifically for my particular application. Unfortunately all he gave me were the numbers: 510 Lift & 270 Duration.

So, I called him a few days ago and asked him to find out what the rest of the cam specs were, (ie. LSA, Centerline, Duration @ .050", Power Range etc....) and this is what the guy faxed him:

----------------------------------------------------------
406ci Chevy Motor

GRIND - # 487 HP

Ratio Rocker - 1.60:1

Cam Lift - 510

Duration .006" Tappet Rise intake/270 - exhaust/270

Lobe Seperation - 110

Centerline - intake/114 - exhaust/106

Cam Timing @ .050 Tappet Rise =

.....OPEN ..........................CLOSE

IN _6_ BTDC ..................38 ABDC

EX _46_ BBDC................- 3 ATDC

----------------------------------------------------------



I'm sorry but I still don't see the duration @ .050" or what the power range should be.

Anyone have a clue?

427Hotrod

Play with this calculator.


http://wallaceracing.com/camcalc.php


JIM

BigBlockk

The information is right there. Your intake duration is 224 degrees and the exhaust is 229 degrees. What more do you want???

BigBlockk

Later.....

str8upchevy

SWEET!!!

Thanks a lot for that,... ...I knew somebody here would know of a formula or a calculator to figure out the duration @ .050" lift.

According to that calculator my cam has a duration split of 224/229. Similar cams show a power range of about 2200-6000,......which is perfect for me since I'm running a 3000 stall converter.

Thanks again Jim!

str8upchevy

What more do I want??? How about an explaination of how you got those numbers?

If there's some series of mathematical calculations you have to do in order to come up with the 224/229, I obviously didn't know what they were or I never would have asked, would I?

I appreciate the answer, but how about explaining it instead of just assuming I should know what it is.

gkull

Simply add 180 degrees to the .050 valve event numbers. I actually came up different on the exhaust side because of the minus 3 So it is something like 224/223. I'll plug these into my DD2000 tomorrow and I could also tell you whether it has some ground in advance.

It is saying that: Your intake opens at 6 degrees "Before Top Dead Center" and Closes 38 degrees "After Bottom dead center"

Exhaust opens at " 46 degrees Before Bottom Dead Center" and closes 3 degrees before (the minus sign) "After top Dead center"

This is a very mild cam. I would wonder about the big HP claim

IN _6_ BTDC ..................38 ABDC

EX _46_ BBDC................- 3 ATDC[/b]

Just for comparison - This is the Crane cam and this is how they rate it on a 350 ci motor

1957 1987 CHEVROLET GOOD TO FAIR IDLE, DAILY PERFORMANCE USAGE, GOOD MID-RANGE TORQUE AND HP, MILD BRACKET RACING, AUTO TRANS W/2500+ CONVERTER, 2700-3200 CRUISE RPM, 9.5 TO 10.75 COMPRESSION RATIO ADVISED. BASIC RPM 2400-5400
Engine Size Configuration
262-400 C.I. V
Valve Setting: Intake .000 Exhaust .000 HOT
Lift: Intake @Cam 3114 @Valve 467 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 3114 @Valve 467
Rocker Arm Ratio 1.5


Intake 278 °
Exhaust 278 °
Spring Requirements: Triple Dual Outer Inner
Part Number 99848
Loads Closed 114 LBS @ 1.700 or 1 45/64
Open 308 LBS @ 1.260

Recommended RPM range with matching components
Minimum RPM 2000
Maximum RPM 5800
Valve Float 6400
Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 6 BTDC 36 ABDC 222 °
Exhaust 46 BBDC (-4) BTDC 222 °

427Hotrod

If you look through that Wallace site it has a ton of very useful calculators to work through all sorts of stuff.


JIM