C6 ls3 CAM HELP
Melting Slicks
Joined: Nov 2011
Posts: 3,174
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From: Virginia
If I remember correctly, I had only changed from stock lifters to the Johnsons on the stock LS3 cam so needed a 7.350 length pushrod assuming a stock preload of 0.080 and going to a preload of 0.035. I believe after the install, I measured right at 0.040 preload. After that, I changed to the LS9 cam and LS9 head gaskets which are slightly thicker. When I measured for pushrod length with that setup, there wasn't any significant change so I was able to keep my existing pushrods. The thing about the Johnsons is they designed them as a true drop-in lifter. While the preload is less than a stock lifter, the plunger dept was changed that exact amount. So if all that you are doing is changing the lifters and nothing else, pushrod length should stay the same.
Glad to hear that the new heads fixed the ticking problem and your car is running good. Definitely worth checking to make sure you have the right length pushrods. It's difficult to find accurate information but the Johnson's are supposed to have about the same plunger travel of the stock lifter. So about 0.200. So technically there is a lot of margin for error. But I assume that internal design of the Johnson requires that shorter preload for a reason. Likely the plunger and oil flow through the lifter are significantly different than stock and so too much preload would likely affect the proper functioning of the lifter. I don't know the physics of how oil flows in and out of a lifter but I'm sure proper function of a lifter requires a certain cushion/reservoir of oil under the plunger to properly dampen valvetrain vibrations. And that will depend on the internal design. Same should be true in a stock lifter. Probably could or would lead to increased wear and tear on other engine components. Likely accelerated valve seat and valve wear if the opening and closing events aren't "cushioned". Probably could also affect the proper amount of pressure of the rollers travel on the cam lobes. I'm sure there are engineers out there who could shed more light on this as I am just guessing.
As for your setup, assuming you went from a stock LS3 engine to the Titan 2 with the Johnsons, lift is increased by about 0.044 on the intake side and 0.062 on the exhaust side. So the base circle of the cam will likely have been reduced requiring a longer pushrod. But Preload will be about 0.045 less with the Johnsons. But the Johnson's also have a little bit deeper cup. I would bet you may need a longer pushrod, 7.425. Just guessing so definitely check.
Glad to hear that the new heads fixed the ticking problem and your car is running good. Definitely worth checking to make sure you have the right length pushrods. It's difficult to find accurate information but the Johnson's are supposed to have about the same plunger travel of the stock lifter. So about 0.200. So technically there is a lot of margin for error. But I assume that internal design of the Johnson requires that shorter preload for a reason. Likely the plunger and oil flow through the lifter are significantly different than stock and so too much preload would likely affect the proper functioning of the lifter. I don't know the physics of how oil flows in and out of a lifter but I'm sure proper function of a lifter requires a certain cushion/reservoir of oil under the plunger to properly dampen valvetrain vibrations. And that will depend on the internal design. Same should be true in a stock lifter. Probably could or would lead to increased wear and tear on other engine components. Likely accelerated valve seat and valve wear if the opening and closing events aren't "cushioned". Probably could also affect the proper amount of pressure of the rollers travel on the cam lobes. I'm sure there are engineers out there who could shed more light on this as I am just guessing.
As for your setup, assuming you went from a stock LS3 engine to the Titan 2 with the Johnsons, lift is increased by about 0.044 on the intake side and 0.062 on the exhaust side. So the base circle of the cam will likely have been reduced requiring a longer pushrod. But Preload will be about 0.045 less with the Johnsons. But the Johnson's also have a little bit deeper cup. I would bet you may need a longer pushrod, 7.425. Just guessing so definitely check.
Last edited by bwill03z; Mar 16, 2025 at 03:48 PM.
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