Neil, i understand what you say has merit, but only when the duration numbers are the same. A no compromise short track cam coming off a corner at 4,000 rpm (?) doesn,t care about any manners much below that rpm. And it needs all the power it can build in rhe low to mid part of the rpm range it will run in.

From watching DV's videos on picking a cam I think he is saying you will be better off if you consider the LSA number first, usually it's a lower number than what people typically end up with, and then pull some duration degrees off the individual lobes themselves to get the idle and vacuum to still work as they should. He claims if you get the LSA way off for what the engine most prefers you have given up free power that can't be easily gained back by playing with the other aspects of the cam design.

Looking at Eric's last video I posted he is showing us the cam card numbers may not be telling the whole story, and some cams may be different just enough that it changed their results, which is a bummer if you participated and came up short somehow.

Videos like that are aimed at people with very limited understanding of camshafts. I think his viewers would have benefitted from him showing and talking about the differences in the valve timing events.

Billy Godbold discusses in his book shows and discusses an example of camshafts from the Comp Catalogue with similar valve timing events, but running different lobes and LSA.

Can anyone tell me is David Vizard has ever worked ofr a Cam company designing camshafts? Or has he ever worked for a race team? I only know of him from his books.

To be fair, the cam testing was with TF240 heads. I then kept the best cam when I switched to the bigger 270 heads and I didn't do another round of cam testing. On my TF240 engine an Ultradyne 260/260 cam was too small, the Bullet 270/270 was too big and the Comp 264/268 made the best combination of torque and power. But the peak was around 660 hp.

After I picked the Comp cam I started to work on the intake and carb. A ported intake and a Dominator picked that engine up over 700 hp. Then I switched to 270 heads and the engine picked up to 750 hp. Playing around with the oiling system moved the engine up to 775 hp.

I tried a bigger cam at this point but it lost power. I tried a 266/271 cam with more aggressive lobes and the power dropped to 750 hp. Could've been the wrong cam choice, hard to say.

I've used the same 264/268 Comp grind in several customer engines since then and they have all run really hard. It is our "go to" combo when a customer wants a 700+ hp Mopar big block. TF270 heads and that cam. Even have a couple of street guys running that cam but it isn't really very street friendly!

From one of his recent videos he said he is a research engineer, and has done consulting work for many race teams helping with parts, and even non-automotive companies including 3M. He said he makes his money off of patents and not designing or grinding cams, however he does have his own cam selection software that he wrote that was created using dyno test data. Dyno data came first and the software was written based off of that.

I think there is one other thing being not talked about , at least to me . And that is whether using a roller or flat tappet cam either solid or hydraulic .
Now I use solid ft cams and am pretty happy with those results . BUT I also remember discussing cam choice here and Billy (RIP) came from a similar direction as myself . Its about compromise for what is available . Mopars generally have stock or a max wedge port , smaller than most others can readily obtain . So if port size is too small to get all that flow you need to open the valve longer to achieve a similar result . It works for me . Can i get more power with a little smaller solid roller - maybe . Am I making decent power with ok street manners - YES . Even if some might consider my 505 a little over cammed .
Dont forget often a roller will have more lift than a ft . Maybe I am wrong but you cant overlook this .

Tex

That's interesting Andy, the Cam in I put in my 517 with the Chapman 285's (that flow slightly better than off the shelf TH 270s) back in like 2007 is also 264/268 @.050 on 108 , and yeah it's a little big for a street car, but the power over 4200 or so feels more like a HEMI than any wedge head I've ever run. And I have mine in at 102 ICL because it's in a Heavy B body. And the Larry Smith Ported 337 intake is a little softer below 4000 but it really comes on in the 5000-7000 range.

A while back Mike Jones quoted me a 252/260 @ 050 on 110 +4 and said that would be about perfect for the head flows I gave him; And what he's recommending is actually one of his LS style lobe designs. I think it should at least equal the HP i have now but will be stronger through the middle,

I haven't pulled the trigger on it yet but I'm about to.

and I think a race solid can easily equal the power of a Roller in a BB mopar, you just need more lift bacause that last .050-.100 is really just for getting the valve to change direction, so on flat tappets I don't even count that bit of lift in terms of the head flow. Solid FT's are Way Way lighter and to me rev just as easily on big Mopars.

Yeah, the Dot to Dot LS challenge with no tuning changes probably skewed each combo's optimum power, but for what the test was I thought it was pretty entertaining.

I would not bring up the Cam Challenge to Mike Jones if you go back to buy your cam. On Speed Talk people in there were trying to get him to enter since he is apparently pretty knowledgeable at cam design. Towards the end of those threads he got pretty worked up over it and at Eric W. also.

LOL, Point Taken!!

It's interesting though the LS3 port on some of the bigger 260+ CC ports are very similar port cross section, Excpect they do it with a 2.165" valve on a 4.03 bore.

These particular Challenge heads flow very close to my Chapman Stage VI's. I Imagine most TF 270's and Edelbrock Victor MW are pretty close too.

EW LS3 BBM Chap MW

.300 222 224
.400 272 285
.500 319 329
.600 352 361

What's also interesting about the Factory LS3 is that they really don't flow very efficiently OOTB considering how relatively big the port is ... they really only flow ~263 @ .400 and 310 @ .550, a ported cathedral port can flow with that with much less cross section.


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