Today, dollar for dollar, is the 318 faster than the 340 ???

66fs said

The "Throw Away 318"

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this bit?
Below, excerpted from an article that originally appeared in Hot Rod Magazine, are the dyno results from a baseline test of a stock 318 engine, and the horsepower gains recorded after various modifications.

• 186 HP at 4000 RPM (Base Platform):
  • 318 non-roller 8:1 compression cop car short block
  • Production 318 cam with 240* adv. dur. .390"/.400" lift
  • Heads were the 4323302 casting (302s) high swirl mileage/emissions heads with the heart shaped chamber (9.0:1 compression installed)
  • 4BBL cast iron cop car intake manifold
  • Thermoquad carburetor
  • Stock exhaust manifolds
  • Factory stock (non lean burn) electronic ignition system
• 217 HP at 4200 RPM:
  • Added a 360 2BBL cam (252* adv. dur. .410" lift)
  • Mopar Performance Electronic Ignition conversion kit
  • Cam and MP Electronic Ignition swap was good for a 31 HP increase.
• 225 HP at 4500 RPM:
  • Added stock 1.88" intake/1.60" exhaust 360 heads with stock springs, retainers and keepers
  • Gave the heads a performance valve job
  • Head swap was only good for an 8 HP increase.
  • Power was weaker than the swirl head combo below 3500 RPM.
• 251 HP at 5000 RPM:
  • Added Mopar Performance P4120249 valve springs to the 360 heads
  • Added Mopar Performance P4286669 cam (260* adv. dur. .430" lift)
  • Holley 0-3310 750CFM vacuum secondary carburetor
  • Edelbrock 2176 Performer aluminum intake manifold
  • Mopar Performance P4286437 headers (1 5/8" primary tubes with 3" collectors)
  • The above items added 26 HP.
• 290 HP at 5250 RPM:
  • Ported and polished the heads
  • Upgraded heads to 2.02" intake and 1.60" exhaust valves
  • Added Mopar Performance P4452033 chrome-moly valve spring retainers with 8* keeper grooves
  • Mopar Performance P4120620 8* hardened valve stem locks
  • Added Mopar Performance P4286671cam (272* adv. dur. .455" lift)
  • Mopar P4120600 Gold Box competition ignition control unit
  • This combo added 39 HP
• 331 HP at 5750 RPM:
  • Swapped the 360 heads for ported and polished 302 heads modified with 1.88" intake/1.60" exhaust valves
  • Mopar Performance P4120249 valve springs
  • This combo produced a 41 HP increase over the previous combination, netting 1.12 HP per cubic inch!
  • This combo also produced more power than all of the other combinations from the lowest RPM on up

Notes:

• All tests were conducted on an engine dyno stand with an unrestricted exhaust system.
• 4323302 casting heads (302s), 4343646 castings and similar castings are 1.78" intake/1.50" exhaust high swirl mileage/emissions heads that were used on all civilian duty M-bodies from late-1985 to 1989.
• Actual cop car engine compression per the 1987 Factory Service Manual was 8.4:1 due to the open-chambered 360 heads. Compression for civilian model 318s with closed-chambered factory 302 heads was 9.0:1.
• The base HP for civilian model 2BBL 318s was about 140, so expect HP numbers a bit less than the above baseline test if you add a 4BBL intake/carburetor and convert to electronic ignition.
• Modifications usually work together to produce results. The 41 HP increase recorded in the last dyno test was achieved because the camshaft was much stouter than a production cam, and it was designed to take advantage of superior breathing heads. A similar increase should not be expected with the same heads and a stock cam.