22 replies to this topic

[liirge]

Remember to run a bead of weld accross the top of the pressed steel rockers, essential if you're running uprated springs and using high revs

[jaydee]

These rockers were probably fitted with offset bushing to alter ratio

I cant believe you got 2mm increase with them, its impossible the rocker arm would be too long for that 

[Cooperman]

One cannot argue with the engineering mathematics.

It is impossible to gain 2 mm additional lift by changing from 1.25:1 to 1.3:1 ratio rockers.

You would need to go from 1.25:1 to 1.7:1 to gain that amount, and it's unlikely that this has been done here.

Mis-measurement most likely.

[greenwheels]

If the OP's mate prefers the pressed steel rockers then stick with it. The difference could be due to a number of factors so if it ain't broke don't fix it.

[Spider]

Another factor to take in to consideration when swapping Rockers is the Rocker Tip Shape, just as the Cam has a profife to give quick or slow opening, the shape of the Rocker Tip aslo does the same, albiet, to a much lesser degree.

 

While I haven't profile checked them, sitting here thinking about the shape of these two Rockers, the Sintered version is 'flatter' than the pressed in tip of the Pressed Rockers, this will give an accellerated opening and maybe even more opening (when using Sintered Rockers).

 

So, if one was to graph the actualy valve opening on each set of Rockers, they would be quite different.

 

This can, of course have all manner of effects, and it could well be that one type works better with a particular Cam Profile / Cylinder Head over the next.

 

As most Cams only have between 6 to 8 mm lift, 2 mm increase while not sounding like much, is HUGE in percentage terms.

[racingbob]

I would imagine my mate has measured it wrong more than likely

 

don't realy know how he done it but would have only been aprox

[racingbob]

Another factor to take in to consideration when swapping Rockers is the Rocker Tip Shape, just as the Cam has a profife to give quick or slow opening, the shape of the Rocker Tip aslo does the same, albiet, to a much lesser degree.

 

While I haven't profile checked them, sitting here thinking about the shape of these two Rockers, the Sintered version is 'flatter' than the pressed in tip of the Pressed Rockers, this will give an accellerated opening and maybe even more opening (when using Sintered Rockers).

 

So, if one was to graph the actualy valve opening on each set of Rockers, they would be quite different.

 

This can, of course have all manner of effects, and it could well be that one type works better with a particular Cam Profile / Cylinder Head over the next.

 

As most Cams only have between 6 to 8 mm lift, 2 mm increase while not sounding like much, is HUGE in percentage terms.

Chris he said 40 mm to 42mm which is what 5% but don't know how he did it I know he only used a tape

measure

[Spider]

 

Chris he said 40 mm to 42mm which is what 5% but don't know how he did it I know he only used a tape

measure

 

 

Jeee sorry mate, I'm not familar with that type of dial gauge. Got a pic?