1956 Buick 4 Barrel Dynaflow cam specs

[Beemon]

Here you go, guys. Better than the Melling SBC-3 cam.

[SpecialEducation]

What's the history/source of the cam that was analyzed?

[Beemon]

It's the original cam I pulled out of my gouged engine block. 

[NTX5467]

camcraftcams.com/catalogs-links/antique-cams 

 

I suspect the valve lift will be higher with the OEM ratio rocker arms, rather than the "checking" 1.50 ratio?

 

The duration and lift numbers are one way to look at things.  Comparing the other numbers on the Cam Card, when what opens and closes, will be where the differences are between two cams of the same duration specs.  How many degrees of rotation existed at "max lift"?  

 

NOW we know!  Thanks.

NTX5467

[NTX5467]

Upon further analysis . . .

 

You might want to go back and look at the event specs for the Melling SBC-3 cam.  You might want to "mic" the lobes on your "used" cam, too.  Your numbers were done with a 1.5 rocker arm ratio, when the stock ratio is 1.6?  Allowing for the 1.6 ratio, that still leaves the stock cam with less lift than the SBC-3, by about .030"  Other than that, the two look pretty close, with the OEM being the milder one of the two.

 

NTX5467

[JohnD1956]

Can someone explain how to read that report? 

[NTX5467]

I had to get it as a picture, THEN I could enlarge it and turn it horizontal.  The lobe lift is on the left, degrees of duration at that particular lobe lift are the figures stringing out to the right of them.  

 

Some of the cam specs have been rated at the .004" lobe lift and others are rated at the .006" lobe lift.  The aftermarket adopted the rating at lobe lift of .050" lift as their standardized checking method, as that gets to "the meat" of the lift curve, leaving out "the ramps" of the love before and after the main area of the lobe's shape.  The 1953 paper which Buick engineers presented to the SAE used 1.50 ratio rocker arms, too.  

 

The main things to look at, in general, is the duration at .004" and .006", as they are SAE standards, plus the aftermarket standard .050" lobe lift, plus the max lobe lift itself.  I suspect the 1.50 rocker ratio was used as a convenience of sorts as that's more of a standard ratio in more modern times, other than some specific engines that had higher ratio rocker arms as stock.

 

These figures were probably obtained via a camshaft checker mechanism.  You can do similar with a cam installed in a cylinder "short block", a degree wheel, thick wire bent for the timing marker,a valve lifter, a pushrod, and a magnetic base dial indicator.  Have to have the timing set installed, too!  And, of course, some paper to document it all!  That's the analog method.  It can consume a good bit of time . . . cheap entertainment that's fun and educational.

 

Enjoy!

NTX5467

[Guest]

Best of knowledge was up to 1956 ratio for stock 322  1.5:1 then for 364 in 1957 changed to 1.6:1 W/cast iron rocker material, then 1.6:1 and rocker material changed to cast aluminum some time later. Dim memory, correction welcomed!

Edited August 13, 2017 by Guest (see edit history)