what pushrods for z06 cam

[djkir23]

ok what size pushrods should i get for my 02 z06 cam in a 04 4.8?
thanks danny

[motoxlifer]

I think you will need 7.35" push rods if the heads haven't been milled or anything but I would ask the people your gonna order them from to make sure.

[chrisj6]

actually ur gonna need longer, 7.425" or even 7.45" if you can find em! The stock are 4.700" and they are just a hair too short with that cam.

Chris

[motoxlifer]

<div class='quotetop'>QUOTE(chrisj6 &#064; Jan 23 2006, 07&#58;45 PM) [snapback]41995[/snapback]</div>

actually ur gonna need longer, 7.425" or even 7.45" if you can find em&#33; The stock are 4.700" and they are just a hair too short with that cam.

Chris
[/b]

Ya your right I had it backwards.

[RedHeartbeat]

If you can measure the cam base circle between your stock cam and the 02 cam you will be able to tell if you need a longer pushrod. All the 4.8/5.3/6.0/LS1/LS2/LS6 engines call for the 7.400" rod. Unless your base circle on the cam changes or you get the heads milled dramatically you should still require the 7.400" pushrod.

[chrisj6]

The valves in the 02+ LS6 cams are 0.6mm longer to make up for the base circle difference, this is not the case for the other LS based powerhouses, so a pushrod as close to that difference will be needed.

Chris

[motoxlifer]

<div class='quotetop'>QUOTE(chrisj6 &#064; Jan 23 2006, 08&#58;25 PM) [snapback]42007[/snapback]</div>

The valves in the 02+ LS6 cams are 0.6mm longer to make up for the base circle difference, this is not the case for the other LS based powerhouses, so a pushrod as close to that difference will be needed.

Chris
[/b]

Does anyone know why GM did this?

[NITROUS]

<div class='quotetop'>QUOTE(motoxlifer &#064; Jan 23 2006, 08&#58;36 PM) [snapback]42010[/snapback]</div>

Does anyone know why GM did this?
[/b]

All of the LSX cams prior to the LS6 had the same base circle radius. There was a problem with that base circle, if we wanted to go to higher lifts: the nose of the cam would approach the same diameter as the cam bearing journals or even above them. The only alternatives were to increase rocker arm ratio or reduce the base circle radius. GM decided to go with the base circle reduction. The ’01 base circle reduction did not require a change in dimensions of any other valve train part, however, the 405-horse cam was a different story. Because the position of the plunger within the hydraulic lifter is not optimal any more–you’re too high in the lifter. There’s different ways to correct the geometry. The one selected to minimize the impact on manufacturing operations was to increase the length of the valve. The valves in the 02 LS6 are 0.6-mm. longer than the valves in all other Gen III engines. With .025-in more intake lift, the same intake duration at .050-in but a little less duration at lash and the same rev limit; something had to be done to the rest of the valve train to keep it in control at high rpm. While the ’02 exhaust lobe doesn’t have quite the agressive profile as the intake, it’s still got more lift, so something had to be done there, too. The choices GM made were to decrease valve weight and increase valve spring pressure. With the higher lift, GM needed to reduce the mass of the valvetrain or start getting into a float condition. GM went to hollow stem intake and exhaust valves, very similar to what we used in the ’96 LT4. GM pushed the edge with a state-of-the-art, 0.8-mm. very thin stuff. The exhaust stems are sodium-potassium filled.

BTW, most of this explanation is a quote by "Hicks" (GM).

Hope this helps.

[RedHeartbeat]

If the stem height is .6mm higher you also have to compensate for the 1.7:1 ratio on the rocker arm. The .6mm is about .024" longer at the valve end and .014" at the pushrod end.

[RedHeartbeat]

The .011" difference at the pushrod won&#39;t be an issue normally. The LS6 had sodium and hollow filled valves to lighten the weight on the valvetrain for a higher revving engine. The LS6 has a higher redline than the LS1 engine.