Wow, finally got the cam today at UPS. It specs out a little hotter than what is is advertised.

Duration @ .050
Intake 215 Exhaust 220.3

Valve lift w 1.7 Rockers
Intake .631 Exhaust .532

Lobe Seperation Angle
114.5

I am very happy with everything that I got, but here is my question: When taking out the old cam in the installation, you of course turn the old cam so the lifter will pop up in the cups. Wont the old cam only pop up the lifters as high as the old lift on the stock cam? There is quite of difference in the lift between the 2 cams. So wouldnt I have problems installing the new cam. I bought penmagnets to hold all of them up as well.

 

The two should actually push them up about the same amount...

The new cam has a smaller base circle to "fit" the lobes on. The lobes can only "stick out" so much before they will interfere with installation (hard to fit through the cam bearings).

My three cams all had the peaks of the lobes pretty well flush with the cam bearing surfaces... One was stock, the other was .558/.559, this one is .531.

The smaller base circle is why you need to run longer pushrods... to take up the slack of the lifter riding lower on the cam.

 

What length pushrods did you use for the 558/559 lift, and what length are you using for your 531 lift?

 

Not sure if this helps any...

Top to bottom: .558/.559, stock, .531. You can sort of see that even with the big differences of the top two cams, the lobes don't really look all that much different.

 

Both 7.4's, NA...

 

.631 lift is BIG. What springs are you gonna run on that bad boy? By the specs, I'm assuming its a Thunder Old Man Cam Or a variant of it.

 

Yes it is the Old Man Cam, (Truck Series) and the advertised lift is .600, The label that was on the box said .631 but on the flow sheet it said .601?????

918 springs and 7.400 pushrods

 

Thats more lift than I'd feel comfortable with. Comp says 918s are rated up to .600 lift.

I'd trust the label. Did they send a cam doctor report? It would have the exact measurements.

 

Yes, they did send a cam docter report and that was the label that said .601 (which now after talking and looking at it is more reasonable number to believe) For some reason the label that was on the cam box said .631, maybe it was just a misprint, because it was hand written. Any ways, this is the first cam that I bought. They did do some testing with a 5.3 in a truck and it made 40rwhp without any type of tune at all. I suspect with a tune the combo will make 60-65 rwhp. I know make 245 rwhp-255 so hopefully I will make 305 rwhp without headers.

 

I emailed Thunder, and they were able to pull up specs for my old cam based off of the serial number. You could always double check like that.