cam duration

To the OP's original question:

My 351C with iron 2 BBL heads. It never knocked on 93 octane; but it would knock on 87. SCR ran just over 10:1 and I used a Crane economy/torque cam with advertised duration of 254/264 and 190/200 at .050". LSA was 114*. Installed with straight up timing. Stock Ford C4 TC and 3.08 rear gear. The chambers were open but I used a TRW forged quench-dome piston for quench effect. Chambers were polished to help reduce knock tendencies. I was not all that aggressive with ignition advance. Carb was a Holley 6619, made for emissions and economy, so it was not a rich running carb that made up for any tendency to knock; if anything, it would have been more likely to knock with that carb.

So, many of that engine's factors 'violated' the rules we speak about so often as limits. I tend to think of those numbers as 'safe' limits; i.e., easy to build to without issues. But that does not mean you can't push closer to the limits. I think the biggest anti-knock factors in that 351C build were (in no particular order):
- Quench
- Polished chambers
- No cam advance
- Not being aggressive on ignition advance. I tried pushing it once, it knocked some, so went back to just a bit more than basically factory advance.

18-19 mpg on the highway, and good torque with that stump-puller cam. Revved to 6500 rpm with good pull (best 1-2 shift point was at 55 mph) due to the good breathing intake and headers and big ports on those heads. The 1.73 stock Cleveland rocker ratios helped the high end breathing too, despite the shorter cam durations, so I have been a believer in 1.6 rockers for Mopar street use since then..... like on the Magnums.