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Ford 351C, 429/460 Max Output II -Drop in- Valves Spring Kit, Hyd Flat Tappet Applications

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Product Description

 Springs Fit Factory Heads, No Spring Seat Machining Required.

MAX OUTPUT II, Drop in Valve Spring Kit, for Single Groove Valves

Application: 351C, BB FORD up to .625" lift w/ Hyd Flat Tappet Cams

This drop in spring kit was developed for use with Ford OE "stepped" spring base heads.

The springs fit factory heads without the need to machine the spring base or remove the heads to bring to the machine shop. Drop in springs can be installed right on the car if required.

These are from our Max Output II series. Max Output spring kits offer increased open pressures to meet the needs of more aggressive and large size cams.

Max Output II kits are for bigger cams w/ between 226-250 degrees duration @ .050" w/ up to .625" lift.

351 Cleveland w/ single groove valves or Big Block Ford 429/460 engines running moderate to very hot cams can benefit with Max Output II springs.

Need help verifying suitability for your cams application?

Send your cam specs to us and include the cam brand and part number or a link to the specifications and we'll advise.  


     Spring Specifications:

  • 1.487" Outside Diameter
  • 110 Lbs @ 1.830 Valve Closed Installed Height
  • 302 Lbs @ .500" Lift
  • 323 Lbs @ .550" Lift
  • 345 Lbs @ .600" Lift
  • 356 Lbs @ .625" Lift
  • Max Lift- .625"
  • Average Coil Bind @ 1.120"
  • Spring seat machining not required





     Kit includes:

  • Sixteen 7 Degree Chrome Moly Steel Retainers
  • 32 Hardened 7 Degree Valve Locks
  • 16 Drop in Max Output Valve Springs
  • Installed Height Diagram




  • 351 Cleveland w/ single groove valves
  • Big Block Ford 429/460 engines.


Requirements- Measure valve spring installed height and shim as needed. 

NOTE- 351C engines w/ multi groove valves cannot use this kit.

Please allow up to 7 days to build and ship this kit.


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