This is an upgrade to your factory rocker arm in 1.65 ratio. The stock rockers are 1.6 ratio so these will increase your current cam's lift by 3%. These are intended to raise the performance of an aftermarket camshaft by slightly increasing valve lift, reducing valvetrain weight (over 27% lighter than the OEM rocker arms, saving 2 pounds total!), reducing friction. By reducing the weight of the valvetrain, the valve spring doesn't have to work as hard and that will reduce the chance of valve float. These have the upgraded trunion bearings compared to the stock rockers. These will work great in all applications: supercharged, turbo, or naturally aspirated 3800 cars. They will work in all series II and III 3800 engines and do not require any supporting mods. However you should make sure that you have enough valve seal to retainer clearance to increase your lift.
- (12) rocker arms
- (6) pedestals
- (12) rocker bolts
The stock pushrods or whatever you were running will work fine with this rockers. However we still recommend checking your lifter preload.
To check for lifter preload or lifter squish you need to first get to zero lash. Turn the engine over so that one valve on a cylinder is open. Because one is open, you know the other is closed, meaning the lifter is sitting on the base circle. With that lifter on the base circle loosen the rocker bolt and then re-tighten with one hand while spinning the pushrod with the other. This way you can tell when everything first makes contact (the valve is touching the rocker tip, the pushrod is touching the rocker & and lifter and the lifter is touching the cam). At this point of first contact you are at zero lash. Everything past this point is lifter preload. Continue to tighten the rocker bolt until the bolt hits its snug point. This is how much lifter preload you have. Each 1/2 turn of the rocker bolt is ~.050 of lifter preload. Your goal is generally to have between 1/2 turn and 1.5 turns if you have stock lifters or 3/8 turn to 1/2 turn if you have Comp or LS7 lifters. As you can see the stock rockers have a lot more room for error.
If you have too much preload and you have exhausted the adjustment of the lifter, the valves will stay open and the car will not start due to lack of compression. If you have too little preload, the valve train will be noisy and you risk exploding a lifter and having a very costly repair.