Poly Induction:
As far as induction, anything but a two barrel intake would be good.
Dual Quad and Three Deuce induction is attractive and powerful but you need to be committed to the spending the money on one or two more carbs and dedicated to keeping them properly tuned for full satisfaction.
For most applications, it is hard to beat a single four intake for easy maintenance and lower initial cost outlay.
The original cast iron single four intake is a dual plane factory manifold that will produce the torque and throttle response you need to propel the “heavier” B-body cars with stock camshafts and “freeway” gears.
If “Cruising the Boulevard” or making the weekend car shows is your style, this manifold is “happy” just to lumber along with a stock cam profile if that is your driving style.
However, the OEM “stock” Poly four barrel intake is capable of 360+HP and 440ft. lbs. of torque if one wanted to "Hot-Rod" their Poly - just to let you know it is a capable intake if you add the HP options of cam/headers/free-flowing exhaust.
The Weiand single four intake is more plentiful than the OEM cast iron four barrel and responds extremely well to all the basic Hot-Rod modifications and performs best in lighter chassis Mopars with higher duration Poly Performance Cams and 3.23-4.10 rear end gears; with the best power coming from a 3.55 or “lower” gear.
The Weiand is “at home” with the larger torque producing 360-402” Stroker Polys and is essential - as in “The Only” intake - for Blower and Fuel Injection modifications made to the 318 Poly.
It is not the best choice for relatively heavy B-body Mopars with stock cams, 2.76-2.91 or so rear gears, and the absence of headers as it will be soft on torque and throttle response under 3000rpm without the required “Hot-Rod“ modifications mentioned above.
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The Edelbrock P600 three deuce is a dual plane aluminum intake which would be excellent for cruising off the center 2bbl. and plenty of power on demand should you desire to use it. The downside is the premium price for a P600 and the added expense of three carbs and some synchronizing lessons.
The OEM stock cast iron dual quad or Weiand aluminum dual quad (WPD4D) is the most powerful Poly intake available when all the requisite Hot-Rod modifications are added.
Both intakes will accept the modern AFB Carter/Edelbrock carbs. WCFB carbs are nice but very expensive to obtain and build because of their affinity to the early 56-58 Forward Look Mopars and they just don’t look “right” on anything past 1959.
The best choice for dual quad carburetion is the modern Edelbrock AFB's; reason - new/modern carbs with no parts availability issues.
Headers and Exhaust:
As with all High Performance Induction and Camshaft choices, it is fundamental that “what goes in must come out.” Therefore, the restrictive OEM Poly exhaust manifolds should be exchanged for a more efficient tube-header design to maximize the inherent free-breathing potential of the Polyspherical combustion chamber especially with the addition of increased duration/high lift aftermarket Poly cams.
TTI Headers are expensive but one of the best choices you can make for your Poly. A Poly needs to "breathe" and the top quality and superior design of the TTI Poly headers when coupled with a good 2 1/4-2 1/2" exhaust system with H or X pipe and Dynomax Super Turbo mufflers will enhance your horsepower, torque, and mileage significantly.
For the budget-constrained Poly owner, the Spitfire Header is a good alternative and works extremely well for “Cruising the Boulevard” and weekend car shows or a daily-driver.
A mild torque style street cam would be another excellent part to upgrade your Poly and would complete your "package" of intake and headers. A “High Performance” cam upgrade is an integral part of making the Poly run powerfully and efficiently. If you are adding headers and induction to your ride, a "High Performance Cam" is the missing link to your equation.
The stock Poly cam profile is extremely small at 240 adv. duration (198@.050" dur.) with very low lift at .405" less valve lash.
There are far better aftermarket cam profiles to suit your specified style of driving - cruising and showing your car; and beyond.
High Performance Poly Camshafts:
Step One:
For a stock/smooth idle but surprising throttle response and acceleration at all speeds I recommend the solid 256/.435" (208@.050")110LC cam profile. Improved Torque and Power from off-idle to 4800rpm. This is the original 1957 "dual quad" cam profile but with much more lift and faster action. This is a good “torque” cam and lends itself well to truck and pulling applications and not just passenger cars.
We nicknamed this profile “Little Big Cam” because of its passive demeanor and startling power over the anemic OEM stock Poly cam from the factory.
Step Two:
A 258/.460” Solid Cam (212@.050”)110LCwill give you a hint of an uneven idle and all the driveable/power qualities of the 256/.435" Solid Cam. Power from 1800 to 5000rpm.
A 256/.450" Hyd. Cam(206@.050”)will give you a bit more of the uneven idle. It has all the driver/power qualities of the 256/.435" Solid Cam and a bit more power than the 258/.460” Solid Cam. Power from 1800 to 5000rpm.
Step Three:
For a more pronounced uneven idle choose the 264/.450"Solid Cam (222@.050") 110LC or 264/.480” Solid Cam (224@.050”) 110LC.
Very good torque, throttle response, and horsepower from 2000rpm to 5500rpm.
The262/.460" (214@.050") 110LC.Hyd. Cam produces a noticeable uneven idle; just enough to let the “other guy at the light” know youare “not stock.”
Power from 2000-5500rpm; although both the solid and hyd. Profiles will still “feel” good at 6000 rpm in a stock stroke Poly 318.
Step Threecamsare “Hot Street” profiles that provide “Night & Day” torque & throttle response over the "stock" Poly cam and by no means approaches "radical;" much like the old 340 LA camshaft of the sixties but with higher lift, faster ramps, and far more power.
These are the largest cams you should run with a stock convertor. For best performance off-the-line they work best with a slightly higher than stock stall convertor (2300-2800rpm stall) and lower rear end gears (3.23-3.91) if you want to maximize the acceleration and power of these cams.
Step Four:
A 274/.480” Solid Cam (230@.050”) 110LC is the beginning of the “next level” of street performance that will lend itself well to occasional strip use.Will make good power from 2500-6500rpm.
The 284/.510” or 525” higher lift Solid Cam (242@.050”) has the distinctive and “classic” Hot-Rod lope at an idle and is an excellent street-strip cam that will put a smile on your face when you hammer the throttle. It performs as good as it sounds and will pitch your stock-stroke 318 Poly car sideways when properly accompanied by four barrel or multi-carb induction, 3.91 gears, and a 3000rpm or steeper stall convertor in a 1962-65 Mopar. We have spun this cam to over 7000rpm and it still felt like it was pulling our stock-stroke 318 Poly in B-body trim.
Therefore, all Step Four cams require high stall convertors,3.23 and lower rear-end gears, 9 to 1 minimum comp. ratio (9.5 to 10 to 1 comp. ratios are preferred)to maximize the design potential yielding the best bang for the buck in performance.
Step Five:
Do you have to ask? These level Five profiles would be considered mainly Drag Strip action cams or Pro-Street Cams to drive the boys crazy at the stoplight with your Rock ‘n’ Roll lope and rumble while clearing the throat of the dual quads or three-deuce induction.
Some examples are…
288/292 .530”Solid Cam (254/258@.050”) split duration 108LC 3250-7250rpm
294/.525” or .550” Super High Lift Solid Cam (260@.050”) 108LC3500-7500rpm
296/.550” Solid Cam (262@.060”) 108LC3800-7500rpm
312/.550” Solid or Hyd. Dual use cam – can be run as either solid or hyd! (254@.050”) 107LC4000-7800rpm in solid profile
Custom grinds are available as well. There are cams for every Poly engine, including, turbocharged, supercharged, nitrous, and fuel injected so no area of street or racing application is left wanting.
Cam Commentary:
For a daily driver that is torque-conscious, or just plain fun beyond the “ordinary” commuter car, I would choose the 256/.435" solid cam or the 256/.450” Hyd. Version if you want a smooth stock-like idle but enhanced driving performance.
Next choice would be the 264/.450" or .480” lift solid cam if you want more of the “Hot-Rod feel” and desire a cam you can grow future Horsepower with by adding a 2300rpm or better High-stall convertor and 3.23-3.55 or steeper rear end gears.
If you are “Cruising the Boulevard“ on Saturday nights or checking out the car shows and want a mild but noticeable lope at idle that says “Does not play well with others“ sound, choose the maintenance-free 262/.460" Hyd. Performance Poly Camshaft (requires Hyd. Poly lifters & Hyd. Poly pushrods).
For those who want that “…are you ready to rumble!” sound from under the hood and are more serious about RPM and like to drop the hammer on the competition, choose the 284/.510” or .525” lift (242@.050”) cam. This baby has it all; decent street manners but really gets with the program when you need it and will rev to the moon in your 318 Poly.
The rest of the aforementioned profiles in Step Five are no-holds barred High Performance Poly Cams that will take no prisoners and are only for the serious Street Prowler looking for a quick bite out of the competition or full race at the Drag Strip. These are pedal to the metal tire-smokers so wear a mask and hang on.
Videosound bytes of the 256/.435 cam and other profiles mentioned are often available so you can “hear” what they sound like. Some files are large and will require a CD to be mailed to you.
A Solid Cam needs approx. ten degrees more Duration than a Hyd. Cam
Rule of thumb. It takes 10 more degrees duration @.050", with a solid lifter cam to run the same rpm of a given hydraulic cam, so a 230 degree solid lifter cam has the same operating range as a 220 degree hydraulic. The reason there is a 10 degree variation here is because solid lifters need a longer ramp to take up the slack in the valve train before pushing on the pushrod, where hydraulics don’t. So, putting solid lifters on a hydraulic cam, as exampled, you wind up with a 210 degree solid lifter cam out of what was a 220 degree hydraulic.
Poly 318 High Performance Poly Rocker Assembly:
Features: hard chromed rocker shafts, fully bushed intake & exhaust rockers,
all rocker tips/faces are machined & trued, and improved jam-nut adjusters are installed to help maintain valve lash settings and pre-load settings when using Hyd. camshafts;
Benefits: improved oiling of valve train and reduced friction for decreased
valve train wear, higher rpm stability, less-frequent valve lash settings due to improved locking adjuster feature.
OK, that is the "sales" pitch, but really, most of the original rocker assemblys are quite worn after years and miles; always good to check the integrity of your unit when rebuilding the motor to see if an upgrade is warranted or wanted.
I can help you with the aforementioned cams/other profiles and any Poly parts sourcing you might need or want; just e-mail or feel free to call me on my cell at any time.
Thank you,
Gary Pavlovich
619-572-3008 cell in CA anytime