ok so i am changing from 1.7 rockers to 1.8. my cam is a 222/224 .566.568. what will the new lift and dur be after the swap.

Thanks

 

.566 divided by 1.7 = lobe lift. Lobe lift x 1.8 = new lift.
I don't know how to figure duration.

 

On the duration you might gain a degree or two if that. Not really a notable difference there. Think of it like this, with the longer rockers the valve will be traveling further just in the same amount of time. Therefore the duration really stays the same, but the valve speed does increase. Make sense?

 

yeah i get the duration thing, was just double checking to see if it changed like i thought it did.

thanks

TIm

 

duration doesnt change at all, its the lobes from the cam that determines the duration, as for the new lift it would be .599/.601. there are some companies that do not recommend 1.8 rockers due to the fast ramp rates of the lobes

 

Why are you changing rockers again ?

 

I agree with you 100%. I was trying to say that with the increased speed/acceleration of the valve, some theory would suggest that the motor "thinks" or will act as though you actually added a tiny amount of duration to the cam. Which in-fact you did not. Do you get what I'm trying to say, cause I hardly do? lol.

 

i am changing them for a little more lift from my recently installed cam so i can utilize the good flow that the heads can do at .600 lift. also i would like adjustable rockers so i can set the preload perfect and try to elim valve train noise.

i here ya about the fast ramp rates however i only have xr lobes not the xer, also the rockers come with shorter pushrods to help reduce deflection

thanks for the explanation, i got it

 

Yeah, good luck with that.

 

well cant hurt trying with some adj. rockers. not much noise now but i think it can be better