67 Cuda: disappointing dyno numbers, need some advice!

Brandt Fonda said
the purple cam is the old grind .450/455 268/272 , I thought with the stamped rockers I may not even be getting a full 1.5 ratio and not seeing all of current cam. My exhaust is TTI 3/4 step headers into 3" TTI X pipe into dual 3" all the way out.

it is indeed the aluminum m1 dual plane. I'm starting to see a general consensus that my heads may be sub par, though I have heard that the 308's flow better than x, j heads. The engine was built by Barnes and Reece in NC. which I have heard is a reputable builder, however they may have just put the engine together how they were asked and may or may not of ported them.

Yeah the stamped rockers probably aren’t a true 1.5”. But a lot of them aren’t and that’s not really the issue.

308’s were a minor rework of the earlier design. Minor. On the intake side they flow almost identically to the J’s, remember the X heads had 2.02’s and the 308’s won’t beat them on the intake side with 1.88’s in stock form. On the exhaust side they flowed better than the J’s. But not amazingly better, just a little better. They had a better exhaust port design, but think along the lines of improved efficiency- not a massive rework or improvement.

308’s in stock form will not easily get you to 400 hp at the crank.

Brandt Fonda said
Are any of you opposed to this: put the Hughes cam in and install the roller rockers keep the M1 manifold and dyno again? If I get into reworking these heads I believe it might be better to just get some good aluminum ones.

I mean do what you want, but like I said, the first thing I’d do is a compression test. Takes 15 minutes. Otherwise you’re just throwing parts at it. If you’re weak in the compression department a new cam isn’t going to be a magic bullet.

And yes, if you need to do a full rework and port on those 308’s it’ll be even money with a new set of aluminum heads if you’re paying someone for porting.