shimming the rockers

[Patrick66]

i read something in the Falcon Six Cylinder Performance Handbook about shimming the stock rockers to achieve the same effect as a high ratio rocker. has anybody done this? what kind of results did you get? my head is off at the machinist getting milled right now and they told me they are backed up so it could be a couple days before i get it back, which gives me time to think about this stuff. im thinking of stopping by my machinist with the rocker arm and seeing what he can do.

im also thinking of replacing my springs while the valve train is all dissasembled, what springs is everyone using? anyone using the 302/289 valves? i may be getting a cam from classicinlines in the future so i want to upgrade my springs now while i have it all torn down anyways.

 

[MIKE/ILLINOIS]

Hi Patrick,
David and Dennis are referring to adding a washer or shim under the rocker assy. where it bolts to the head. The reason is to keep from having to get shorter push rods after milling the head. i.e.-take off .020" off of the head surface and then your rockers are .020 closer to the block hence your pushrods are now .020" too long. Hydraulic lifters can compensate for some of that, but I'm not sure how much. Shimming the rocker assy. like that wouldn't effect your rocker ratio. Hope that helps some. This is one of those times when a picture would be worth a thousand words!! Good luck!

Mike

 

[CZLN6]

Howdy Patrick:

You didn't read that in the Handbook. Shimming the rockers will not change the rocker ratio or effect valve lift.

Additionally, for an engine with hydraulic lifters you do not need to consider milling or shimming the rocker arm staunchions. Hydraulic lifters can compensate for small amounts of milling, up to about .125". Save your money for a set of adjustible rockers. Problem solved.

If you want to gain some flow through machining, reread the page about back cutting the intake valves for a low cost/good return.

Adios, David

 

[Patrick66]

ok

well i milled the head .030 so i should be ok.