Quote:Factory double springs are for 6600 rpm use, but usually work up to 7000 rpm. If your cam is to run higher than that, buy the matching Tomei valvesprings.

No need to remove the factory inner spring during initial run-in. But if you are running very stiff aftermarket springs you might want to.

thanks dd
il keep researching more about engine run ins.

Yes, you can measure them in place. Measure from the rocker shaft to push rod. Shorter distance mean higher ratio. The difference between stock arms and Nismo arms is too small to be noticed without measuring.

Hey guys

Some noob questions.But its the only way to learn.

just received my nismo high ratio rocker arms.
Also Just noticed the arms on the modded head i got from japan look modified/lightened.
They also look similar size wise to the nismo rockers. My question is, is there a way to measure the rocker arm ratio of the ones on the head without disassembling the rocker tower?
i have a feeling the ones currently on the head aren't stock ratio but waiting on advice on how to measure them. Visually the length looks similar but looks could be deceiving.
checked wiki but no info.
The head also came with double valve springs.Is there a way to measure if they will hold up to a long duration ,high lift camshaft?Ive got a brand new and nla tomei camshaft enroute from japan.
I've read on other threads about valve floating and coil bind so trying to avoid learning the hard way.
My last question is how to run in engines with double valve springs as ive read from some sources that they remove the inner springs to run in the engine.

any info will be appreciated.Thanks guys
a few pics for illustration.Nismo high ratio rocker arm on the end for comparison to the modified current arms.will put more pics of items on photo album when i get time by next week.

cheers

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