i have a 355 tpi zz4 engine with 10.5 to 1 compression,im putting full roller rockers on my engine, im putting 1.6s on my intake and 1.5s on my exaust, i read from tpis you can get 20-30 more horse power this way , has anyone out there tryed this, it says to have been dyno proven, thanks

 

i have never heard of that before. so i dont know if its true or not. what comes stock as far as rocker ratio? just curious

 

i dont understand that...it would just limit the lift on your exhaust

 

right thats what im thinking... exhaust ports are already smaller

 

1.5 is stock. but i dont see how 1.6 on the intake and 1.5 on the exhaust would make the most power might as well put 1.6 on both to get more lift on the exhaust

 

right... that way you have more overall flow, instead of restricting the exhaust flow... right?

 

thats exactly what im thinking. to me thats like getting an intake, intake manifold, porting the intake ports on the heads, but not touching the exhaust ports and leaving on the stock restrictive exhaust manifolds

 

im running 1.6s on all of them what springs do i need

what kind of valve springs do i need to run all 1.6s on my engine the lift should be around 504 intake and 540 exaust , thanks

 

Could be wrong but I think I recall reading that it was 1.5 Intake/1.6 Exhaust but you could verify that by looking at SUMMIT catalogue or contacting their Techs because they list one or more "Mixed" sets of Roller-rockers. In addition to making sure you don't get Spring-bind, you will have to grind the Heads where Pushrods go thru about 1/8", if you have pressed-in Rocker Studs you will need to change to Threaded, and if you don't buy self-aligning Rockers you will need to fit Pushrod Guides

 

Split ratio rockers are used to correct for not-ideal camshafts or are application specific in racing engines; a zz4 motor, put 1.6s all the way around.