Warning - upgrading from single to dual springs on aluminum head


Famous Member
Greetings Ford Six Fans,

My aluminum head (purchased from Mike Winterboer in 2013) came with single springs with dampers. This was fine for six years or so, as I was running a Clay Smith 274/274/108 cam with .300 lift (.480 lift with 1.6:1 rockers). On my 250 engine, this cam made HP up to 5,100 RPM, and I set a rev limiter at 5,500 RPM.

As part of a recent engine upgrade, I wanted to run the Clay Smith 280/280/110 cam, which has .320 lift (.512 with 1.6:1 rockers). This cam also has longer duration and should make power at a higher RPM range. With the higher lift, duration and RPM range, I wanted to install dual springs to better control the valve and prevent float at high RPM.

Unfortunately, the heads that were originally assembled with single springs with dampers have a steel spring locator pressed onto the valve guide:

This spring locator cannot be left in place if installing dual springs: this would sit under the inner coil and result in too much pressure from the inner coil. Because this is pressed on, it must be either machined off, or the valve guide must be removed to remove the spring locator. My machinist tried to machine the steel spring locators off, but on five of them, the valve guides broke loose during the machining operation, so the steel spring locator could not be machined off. Now, the machinist will have to drive the valve guides out to remove the spring locator. The valve guides may be damaged by driving them out, and may need to be replaced. I don't know how long it will take to find compatible valve guides if necessary.

None of this is very expensive, but don't expect to upgrade the aluminum head to dual springs quickly.



Supporter 2018
Supporter 2021
Might as well add that the valves are too short.
The retainer height doesn't allow room for a steel spacer under the valves springs to protect the aluminum head.
It also severely limits the choice of spring that will allow the head to be used above 6000 rpm.

Manley has been able to supply longer valves to address these issues.
  • Like
Reactions: DMT