mercruiser engine tuning mercruiser engine tuning


Special Preperation 5.0 / 5.7 litre (305 / 350 cid) to 280- 340 BHP @ 4400 RPM.

1 x pair “Swaymar” high performance cylinder heads consisting of :-

  • 8 x 1.940” S/S intake valves
  • 8 x 1.5” S/S exhaust valves
  • 16 x high performance springs
  • 16 x competition grade valve spring retainers
  • 32 x forged cotters
  • 16 x screw in high tensile rocker studs
  • 8 x hardened steel push rod guide plates.
  • 1 x Special “Swaymar” high torque “fully roller” camshaft to give much more torque in the low to mid range while still attaining between ** 280-350 BHP @ 4300-4500 RPM. Complete with :-
    • 16 x full roller tip followers.
    • 1 x full follower guide kit.
  • Competition quality adjustable “Duplex” timing set for dead accurate valve timing.
  • ** dependent on engine size ( 5.0 or 5.7 litre)
  • #1 x high performance aluminuim intake manifold for 4 barrel carburetor.
  • 1 x 600 cfm 4 barrel marine carburetor.
  • 1 x high flow flame arrestor type air filter for 4 barrel carburetor.
All necessary gaskets, oil, spark plugs etc. supplied.

# please note this type of intake manifold should only be used with “Fresh Water Cooling System” unless engine is to be flushed EVERY time used.

Strip all old units from engine, clean, and reassemble with new components, and test run to set up carb and timing prior to collection of engine from us. £ 3727 : 00

If required while job is being done, special discounts are allowed on the following and include fitting while the engine is being built.
Fresh water cooling kit Normally : £1,100 Special Price : £975
Stainless Steel exhausts Normally : £1750 Special Price : £1,500
Full Silicone blue 20 year life hose kit Normally : £425 Special Price : £355
All prices are + VAT ex works

This is the standard combustion chamber as used on all 5.0 and 5.7 litre GM small block marine engines. (good for trucks but definitely not optimized for either gas flow or good flame path, both of which are essential for good power outputs)
This is the completely re-designed combustion chamber used by “SWAYMAR” on our performance engines and upgrades, when used with our high torque cam this can give 40-60 BHP increase, and more when used with some other upgrade components.
High energy Roller tip Rocker used on “SWAYMAR” high output engines, these rockers not only increase valve guide life by 400 to 500% by eliminating side loading on the valve stems. But ensure that all valve lifts are exactly equal as they are precision items, ensuring all cylinders run far more equal, for a smother more powerful engine.