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split ratio rockers

7K views 4 replies 4 participants last post by  engineguy 
#1 ·
is fine to have 1.6 arms on the intake and 1.5 on the exhust or does the engine have bad exhust flow replys much appreciated
thanks
 
#4 ·
If your cam had the same lift and duration on both the intake and exhaust lobes you would benefit by using the 1.6 on the exhaust side.
There however is a downside to this, being the final lift and interference with pistons if you are running any decent size cam lobe.
Without knowing whats inside the engine for valve clearance, you could make a very costly mistake.
 
#5 ·
Changing the rocker arm ratio on only the intake or only the exhaust is done very frequently as a drag strip tuning aid. Works somewhat the same as advancing the cam. Depending upon the engine combination, going to a higher ratio intake rocker will result in more bottom end power and the higher ratio exhaust will result in more top end power.

Remember though, just like advancing or retarding the cam, these changes do not result in MORE power, just changes the power to rpm relationship. i.e., if you gain additional power at low rpm, you will generally lose approximately the same amount of power at higher rpm.

Also, the valve to piston clearance must be checked when changing to a higher rocker arm ratio.
 
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