I imagine they will be here by Christmas.
I've spent hours this week in conversation with Billy Godbold from Comp, along with my normal engine builder support guy there, Chris Ryan.
I came into this with the intention of making the 390 spin up, and spin up we did. However, to insure that I had every advantage to do that, I chose a pretty lazy camshaft. An aggressive lobe makes it easier to lose control of the valvetrain. A lazy lobe makes everything quiet and easy to make things go up and down.
With a lazy lobe comes a ton of overlap. I've spoken about this in the other threads, but we're at 91° of overlap for a "little" 390. I think there's a lot of power to be had with a more aggressive lobe and that's what we're gonna try next.
I came at it thinking I had too much overlap. Billy came at it thinking that FE's are just not as rigid up top as something with a stud mounted rocker arm. I did a couple of spring pressure vs lift loss exercises for him and gave him some data to work with.
So that's why I have two camshafts coming.....one is another one of my selections, based on a slightly more aggressive LS engine lobe and the other is based on Billy's selection. Billy's selection is actually based on lobes that have "lash ramps". His thinking is that he can open the valve slowly at first to "take up the slack" so to speak, and then go ahead with accelerating the valves open.
All-in-all, anyone on the outside looking in would think that the 3 cams (the current one and the two new ones) are basically the same. The difference is in the details....hydraulic intensity, major intensity, and major intensity spans. These are not inputs that you can shove in simulation software, so the proof will be in the pudding.
Current camshaft is 314/324 @ .006", 259/269 @ .050", 114/107, .635"/.635".
My next selection is 311/311 @ .006", 258/258 @ .050", 112/112, .616"/.616".
Billy's choice is 323/333 @ .006", 257/267 @ .050", 112/112, .655"/.663".
The orders are placed and Comp threw in their new MSE micropolishing treatment for free so I could try it out.
At this point I don't know whether I'll do it in 2 separate dyno sessions or buy one of Jay's 2-piece timing covers and hit it all in one day.
My goal is to keep the same 7000-7200 horsepower peak, but I'd really like to see 575 hp out of this thing.
