Which heads?

318willrun said
If I was to use magnum heads, I would just put the whole magnum motor in the car. I have a pair of good 318 heads on the car and a good pair of 308's on the bench. I know there is gain going either way, but I'm trying to reach high 13's on a very mild 318. Every tenth counts, that is why I'm interested in different perspectives. Keep in mind, I'm using manifolds instead of headers, and that will help low end torque if I was to use the 308

When I was 19 I had bought a '74 E body with a 3sp stick, 318, 4bbl, headers, etc. I replaced the 318/3sp with a bone stock re-ringer '69 340 and 4sp. The only change to the engine was the cam to a Comp High Energy 268H, a double timing chain, and a Thermoquad intake and carb. In that shape the car would run mid 13s with 3.23s. The 340 lost some ring lands due to a nice lady who helped me after I ran out of gas one day. I pulled the 340, swapped the X heads and racey parts onto the bone stock '74 318 shortblock and stuck it back in the car. On follow up runs that car would go no better than 14.0s. I then replaced the X heads with the 318 heads in order to sell the 340 as complete core. With the 318 heads, a set of MP valve springs on them, and everything else the same including the mismatched thermoquad intake, then car picked up and went 13.8s. I've had a few years of R&D and learning since then and all the fancy tools and equipment has evolved. If you want a torquey 318 and don't muddy the waters with talk of porting, fresh machining, replacing core parts, or much for HP parts - my advice is don't put 360 heads on it.