318 with 340x heads sluggish

RustyRatRod said
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Here is what's happening. First, your compression is LOW. The 318 had heads with smaller chambers. Installing 340 or 360 heads on a 318 lowers the compression down into the 7s. You're probably at 7.7 or 7.8:1, possibly lower. That's the first killer.

Killer #2 is the "mildly aggressive cam". That cam, coupled with the already dismal static compression, makes any left over cylinder pressure plummet. Goodbye power.

Killer#3 is that converter coupled with the 3.23 gears. What's happening there is, the converter is actually stalling up higher than it should, because it does not have the leverage of a better gear ratio. Converter slip city. If you had 3.91 or 4.10 gears, at least THAT part would be better.

The best thing you can do is several fold. Get some 318 heads back on it. Get a cam in it with around 210-216* duration @ .050". Degree it in.

Then, toss that converter and put a stock one in. You will have a completely different car.

Oh and get those stupid lookin wheels off. Mopars ain't ghetto.

I used to build 70's 318's with 360 heads, they were cheap, and they always ran good. Always milled the heads, block side, .020 or .040, and intake side, .019 or .038. If you need new pistons, get some 9.0:1. The rest of the recipe was as RRR has outlined for you, although I usually ran 3.23 gears. The cheapest solution is to try and tune what you have first. I have seen timing marks off, over 10 degrees. The cam usually is usually not that far off, but you need to know what you have and that it is installed correctly. There are lots of threads here, that tell how to time and adjust your carb for max power and efficiency.