In our current world of 1000 horsepower HellCats with factory a/c and a factory warranty, 230 gross-rated horsepower seems more like a lawn tractor engine, by comparison. Yet when the 1966s were new, about 500 real dyno horsepower meant factory a/c was not available (especially with the RV-2 compressor) for many reasons.
Although the Poly 318s could have had a factory "power pack" 4bbl and dual exhausts in 1958, by the middle 1960s, with the larger 383s and RB motors as "power options", the Poly motor was relegated to normal "drive around car" status. With a small 2bbl carb, too. Yet it was also the first engine in the Travco motor homes (with truck-style rear axle ratios and such).
When I saw my first 301 (Plymouth) V-8 block at a machine shop, I was amazed at how much stronger it was in the main web area than the beloved small block Chevy V-8! But with its heritage including the Gen I Hemi motors, not a real surprise.
Camshafts, back then, were more like "bumps on a log", compared to modern engines. Similar with exhaust manifolding. We've learned a lot since back then! At this point in time, cam choices can be more limited than for a later LA motor, though. Same with better exh manifolds, too.
I'm not sure if a later LA cam will work in a Poly A motor, considering the architecture similarities. Even with the stock exh manifolds, a good 2.25" dual exhaust system with Street Hemi mufflers (or thereabouts) can help that side of things. Add a 4bbl intake with a 600cfm-style AVS2 and that could help things a bit on the total rpm spectrum, even with the stock cam. Then a one-notch-looser torque converter, similar to the old '68 Road Runner converter, for "the icing". The car should already have a 2.93 rear axle ratio. Might head over to the Hot Heads website?
Front sway bar? In 1968, CAR LIFE magazine did a comparison test of "standard V-8 full-size 4dr sedans", which included a Fury III 318 2bbl car. As was their practice back then, they did a full-on shot of the cars in a corner at the same speeds. That Furi III was leaning in the corner and the front wheels were leaning, too. NOT what I wanted to see, but they also mentioned it was the ONLY car without a factory front sway bar in the group. That's when I discovered the 318 cars didn't have one, but the B/RB cars did, as standard equipment. Compared to the later 1969 tests of B and RB C-bodies, that '68 Fury III looked more like a '54 car than a 1968 car, to me. Many might not notice the difference in their normal driving patterns where ultimate handling is not a consideration.
If you look at modern engines of the past 10 years or so, you'll discover that a bore size of about 4" is where most of them are, with the CID increases being related to "stroke" dimensions. Something about the speed of the flame front being more efficient with the 4" bore sizes. Guess where the Poly and LA motors are. Which, once again, meaning power production is "in the heads, intake, and exhaust systems". Having valves which open away from the cyl bore walls is better, too! Guess where the Poly or "single rocker shaft" motors are?
MANY things to recommend a Poly 318 over the LA 318, just that those advantages were over-shadowed as they were not fully understood back than and the bigger B/RB motors were where all of the emphasis was. By that time, production costs were also a consideration!
Path of least resistance? Carb, intake, exhaust system. Cam? Aim for something close to the LA340 cam. Then do the one-notch-looser torque converter if desired. You might be surprised.
Just some thoughts,
CBODY67
