Current cam: Isky Street Roller
290/290 advertised
248/252 @ 0.050"
.602"/.646" lift

I was thinking about possibly installing 1.8 rockers on the intake only for a little more lift. The springs that I'm running will handle the additional lift.

Is there any reliability issues with 1.8 rockers.
Not sure, but doesn't a larger ratio rocker add a little duration, if so about how much? Does the added ratio have any effect on the .200" duration?

To my understanding, the "total lift" does not really impact V-P clearance, correct?

Thanks in advance. smile.gif

Yes, it will increase duration slightly.

.050" duration would be something around what your current setup is at .047" now.

.200" duration would be around where your current .188" duration is now.

I've wondered about durability for a long while though, especially 1.8's on a BBC ... and will be curious to see the responses. My feeling is that a different cam is the correct way to get the increased lift/duration you want? Am I right?

Neal

Darren,
The hi ratio rockers are a tuning aid that may or may not give you any power.
It depends on the head & what it likes.
You will not increase duration at the seat assuming you adjust the lash correctly for the new rocker.
What you will do is increase the whole valve area or make the engine see a more aggressive cam profile which is all the engine cares about anyway.
Only problems are when you use hi ratio rockers on a cam profile that cannot support the added acceleration which in your case is probably not an issue.
Again, it depends on the profile.
If the lifter & valve follows the cam reasonably well you will probably see a gain in power just as you see a gain in power with a roller that lets the cylinder see the port more effectively for a longer period of time without compromising tuning or seat to seat timing.
Bottom line, if you head likes the added lift & duration your engine will be happy assuming the valve follows the intended path. ;)

Of course, you need to check geometry, coil bind retainer clearance, head clearance,,,, all the "normal" I changed something & now it don't fit stuff smile.gif