Should I get new rockers?
Should I get new rockers? Just got a set of 241 cast heads ported by CFM. Intake at .600" lift I get a 305 airflow. The numbers start to drop after that. Exhaust is 208 at .600" and keeps climbing.
Aftermarket stainless steel valves have a 2.02" intake and 1.6" exhaust diameter.
I was thinking about the xr281hr grind from comp cams as this should put me around a .571" lift, with stock rockers.
My thought was get a 1.7 ratio rocker set to put me near .600" lift, thus getting the best airflow with my new heads.
Heard some old war stories back in the early 2000's with problems with some of the aftermarket rockers for the ls1 out there. What have you used and how has it treated you?
Not looking for someone to post on what they just bought, no offense but looking for real data. Thanks!
Aftermarket stainless steel valves have a 2.02" intake and 1.6" exhaust diameter.
I was thinking about the xr281hr grind from comp cams as this should put me around a .571" lift, with stock rockers.
My thought was get a 1.7 ratio rocker set to put me near .600" lift, thus getting the best airflow with my new heads.
Heard some old war stories back in the early 2000's with problems with some of the aftermarket rockers for the ls1 out there. What have you used and how has it treated you?
Not looking for someone to post on what they just bought, no offense but looking for real data. Thanks!
If you have the money and going with a high lift cam I would stick with 1.7 ratio and get a set of yella terras. If Im not mistaking stock rockers like to side load the valves when you get agressive with the cam. Please correct me if Im worng.
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I don't use them anymore. Now stock rockers are used. Have used 1.7 rollers w/ XER lobed cams & 1.8 rollers on stock lobed/low lift cams. IMO, roller rockers are not worth the expense.
One thing to watch for with stock rockers & higher lift aggressively ramped cams are the bearing retainers popping off & dumping needle bearings into the head/engine. There is a kit sold that is a cage for the needle bearings that eliminates this problem. To me, the kit is also over priced. So, I just tack weld the retainer to the rocker. This keeps 'em from popping off (see pic).
I don't use them anymore. Now stock rockers are used. Have used 1.7 rollers w/ XER lobed cams & 1.8 rollers on stock lobed/low lift cams. IMO, roller rockers are not worth the expense.
One thing to watch for with stock rockers & higher lift aggressively ramped cams are the bearing retainers popping off & dumping needle bearings into the head/engine. There is a kit sold that is a cage for the needle bearings that eliminates this problem. To me, the kit is also over priced. So, I just tack weld the retainer to the rocker. This keeps 'em from popping off (see pic).
One thing to watch for with stock rockers & higher lift aggressively ramped cams are the bearing retainers popping off & dumping needle bearings into the head/engine. There is a kit sold that is a cage for the needle bearings that eliminates this problem. To me, the kit is also over priced. So, I just tack weld the retainer to the rocker. This keeps 'em from popping off (see pic).
If the concern is weight reduction, then hollow stem valves can be used. Lightweight valves are a much better benefit than light rockers. The valvetrain harmonics will benefit from hollow (sodium filled) valves over rocker mods. As far as friction, yeah, it is less w/ rollers, but, again not worth the cost, IMO. Best improvement from using adjustable roller rockers is the ability to have a narrow centered valve wipe pattern. Noise...? The resistance of dual springs that are required for higher lift, more aggressively ramped cams, will make more noise regardless.
