I have a Comp Cams Hyd Retro Roller cam in my SBC 355 the cam has 520 lift on the intake with 1.5 rockers and 540 lift on the exhaust with 1.5 rockers and I have a set of 1.6 and 1.5 Crane Cams roller rocker arms and was told to install the 1.6 rockers on the intake and the 1.5 on the exhaust so I'm thinking that will make the cam like 550 lift on the intake and 540 on the exhaust does this sound right and will there be a increase in performance this way or why do people put different ratio rockers on engines with the intake lift being more than the exhaust lift?THANKS :?: :?: :?:
SBC ROLLER ROKER ARMS RATIO ???'S
- Thread starter dickeymoore
- Start date
What's the duration numbers? I would suggest checking the piston to valve clearances.
Different ratio rockers are usually used on single pattern cams. It's to help the exhaust side.
Different ratio rockers are usually used on single pattern cams. It's to help the exhaust side.
Duration is 236/242 @.050 engine is running with Comp magnum 1.52 roller tip rockers just changing to full roller rockers.THANKS
Took head off used Playdo and checked piston to valve clearance and all is GOOD so will it be good to install 1.6 rockers on the intake making the cam like 550 on the intake and 540 on the exhaust?THANKS
dickeymoore said:
Not quite. Check the pushrod slots in the heads to be sure that the pushrod doesn't hit the spring side of the slot due to the change in location of the pushrod cup in the rocker.
So what is the purpose of putting 1.6 rockers on the intake valves which will give the cam more lift than the exhaust lift? ? Thanks
I think it varies by engine, but yes it would be more lift & duration on the intake... .520 with 1.6 rockers would be about .555" lift. It would be hard to guess duration due to different ramp profiles, but it will be slightly longer.
