what pushrods for z06 cam

[motoxlifer]

Here's a link to a pushrod length calculator. It's really a cam guide but scroll down to the pushrod section.http://www.ls1tech.com/forums/showthread.php?t=327734

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jan 23 2006, 08&#58;45 PM) [snapback]42012[/snapback]</div>

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.
[/b]

So are you saying GM did this to reduce the rotating wieght/mass of the camshaft?

[motoxlifer]

"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."


OK now I&#39;m now I&#39;m confused. If the original LS base circle won&#39;t allow larger lift cams without the lobes being bigger than the cam journals then how is, my cam for instance .600 int. & .578exh lift, and the stock cam had somewhere around .500 lift with the same base circle. The LS6 cam doesn&#39;t have .600" lift does it? I&#39;m just not understanding the need to reduce the base circle to get more lift when we can go out and buy aftermarket cams with way more lift than the LS6 cam and the same base circle as the original LS1 cam. Am I missing something?

[RedHeartbeat]

they reduced the small diameter on the cam lobe so that the highest lift point on the lobe will not be larger from the camshaft centerline than the bearing journals. If you were to take the high lift cam and roll it on the table, they didn&#39;t want the lobes to make contact with the table. If you kept the stock base circle and kept grinding taller lift lobes, it would get increasingly difficult to install the cams plus you you be pushing the lifter higher and higher out if it&#39;s bore. By reducing the base circle it gave them more room to increase lift.

[motoxlifer]

I understand the thinking behind it. What I don&#39;t understand is why you can go out and buy a cam with more lift than the LS6 cam but with the LS1 base circle and have no valvetrain geometry problems. The lobes on my cam aren&#39;t taller than the journals and it has quite a bit more lift than the LS6 cam.

[RedHeartbeat]

Hmmmmm, I thought Thunder Racing got their cams from Comp. I know they are ground on TR&#39;s specs. Maybe TR saw that with the final amount of lift they were specifying it wasn&#39;t high enough to change the base circle yet. I have seen guys running almost 1.000" lift on their drag racing only LS1s. If they didn&#39;t change the base circle on one of those they&#39;d definitely would either have to increase the cam bearing bore size or reduce the base circle just to install the cam. Those extreme lift engines most likely don&#39;t have the cam blank like ours that have a hole drilled all the way through it for lightening.

[motoxlifer]

Ya I can see a really huge cam needing a smaller base circle but the stuff we&#39;re runnin and the LS6 cam I don&#39;t understand the need. I&#39;m pretty sure my cam has the larger base circle, right? If not then TR owes me an explanation and some longer pushrods.

[djkir23]

ok im using the stock rockers off my 4.8 which should be 1.7 right? im also using 00/01 ls1 heads. so does that change anything? i was gonna buy some 7.4 moley ones that are a little thicker.

[RedHeartbeat]

Is it possible to put LS1 heads on a 4.8? I thought the valves would interfere with the cylinders. If you plan on going higher lift of turning some serious RPM I would definitely suggest getting the hardened pushrods.

[motoxlifer]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jan 29 2006, 08&#58;59 PM) [snapback]42651[/snapback]</div>

Is it possible to put LS1 heads on a 4.8? I thought the valves would interfere with the cylinders. If you plan on going higher lift of turning some serious RPM I would definitely suggest getting the hardened pushrods.
[/b]

Hmmm... have you ever heard of this happening? I&#39;m just curious,I don&#39;t know. I would have thought that all the LSX heads were basically the same other than port volume,comb. cham. vol. & valve size. Is that why the valves would interfere cuz they&#39;re bigger & the 4.8 bore is smaller. If so does that mean you can&#39;t put bigger valves in a 4.8?

[docone882000]

You are going to loose compression if you do not mill the ls1 heads. Just somethng to keep in mind. You will go from 9.5 to almost 8.5

Here are some basic numbers on the heads

truck engine specs
chamber 61.15cc
comp. 9.5:1
in port. 200cc
ex port. 70cc
in valve 1.89in
ex valve 1.55in

ls1 engine specs
chamber 66.67cc
comp. 10.1:1
in port 200cc
ex port 70cc
in valve 2.00in
ex valve 1.55in

This is what gm says about z06 cams

New for the 2002 Corvette, the 405hp camshaft for the LS6 engine option. Please note that this cam has approximately a 0.050" smaller base circle than a stock LS1 camshaft. This smaller base circle will require longer pushrods for applications with stock length valves and no milling for the head surface. It is imperative that you check your pushrod length when purchasing this cam. The 2002 Z06 cylinder heads use a longer valve to make-up this difference&#33;


So from what I can tell it depends on the yr of the cam. I hope this helps some.