Solved. Truck Norris cam install need help!

[Byoung1330]

What’s up guys. I got a 04 tahoe 5.3 LT flex fuel 2wd. I upgraded timing chain oil pump did the truck Norris camshaft .560 springs that come with it an the seals. Also they said 7.400 pushrods will be fine. I have stock heads and lifters still. They’ve never gave a problem or sounded bad. Engine is quiet. Installed everything an had it tuned. Sounds awesome. After the engine warms up I hear a tick. Found broken manifold bolt bought one them dorman exhaust clamps. Anyway engine is very quiet when I start it an after I warms up I can hear a slight tap while driving. When I get on the gas a little it goes away. After doing a bunch of research I see lifter pre load an all this. I should probably buy a pushrod checker an make sure the length is right. But it’s kinda confusing. I get to check for zero lash an count the turns an all that. I’m not 100 sure how much pre load stock lifters need. The web is full of pre load for ls7 lifters. I pulled my valve covers off an u can spin the pushrod with your finger tips. Not easily but u can. I pulled one pushrod out an installed 7.425. Can’t spin it. Wondering if that would be to long. The guys at Brian tooley said the 7.400 should be fine. An I’ve heard these ls motors have a tap that’s normal after cam install.

 

[S33k3r]

What oil are you running? I'm thinking a slightly thicker oil, or maybe a slightly different type of oil may solve your problem. It definitely sounds like something is expanding with heat, so it's always possible it's something else. I'd recheck all of your exhaust, for example.

Just my $0.02 worth.

 

[Byoung1330]

I have done some experiments so far lol. I’ve ran castrol edge with titanium in 5w30 an 10w30 an yesterday went to penzoil platinum 5w30 An I’ve tried wix filters an yesterday threw a Mobil one on.

 

[Byoung1330]

What oil are you running? I'm thinking a slightly thicker oil, or maybe a slightly different type of oil may solve your problem. It definitely sounds like something is expanding with heat, so it's always possible it's something else. I'd recheck all of your exhaust, for example.

Just my $0.02 worth.

And I did check my exhaust after putting the clamp on the broke bolt

 

[thingraylinetah]

Piston slap probably

 

[swathdiver]

What’s up guys. I got a 04 tahoe 5.3 LT flex fuel 2wd. I upgraded timing chain oil pump did the truck Norris camshaft .560 springs that come with it an the seals. Also they said 7.400 pushrods will be fine. I have stock heads and lifters still. They’ve never gave a problem or sounded bad. Engine is quiet. Installed everything an had it tuned. Sounds awesome. After the engine warms up I hear a tick. Found broken manifold bolt bought one them dorman exhaust clamps. Anyway engine is very quiet when I start it an after I warms up I can hear a slight tap while driving. When I get on the gas a little it goes away. After doing a bunch of research I see lifter pre load an all this. I should probably buy a pushrod checker an make sure the length is right. But it’s kinda confusing. I get to check for zero lash an count the turns an all that. I’m not 100 sure how much pre load stock lifters need. The web is full of pre load for ls7 lifters. I pulled my valve covers off an u can spin the pushrod with your finger tips. Not easily but u can. I pulled one pushrod out an installed 7.425. Can’t spin it. Wondering if that would be to long. The guys at Brian tooley said the 7.400 should be fine. An I’ve heard these ls motors have a tap that’s normal after cam install.

See if you can isolate the source of the sound with a long extension to your ear or mechanic's stethoscope.

 

[Byoung1330]

See if you can isolate the source of the sound with a long extension to your ear or mechanic's stethoscope.

I actually figured it out. I went from 7.400 pushrods to 7.425 an it took all the noise out. More lifter pre load

 

[iamdub]

I actually figured it out. I went from 7.400 pushrods to 7.425 an it took all the noise out. More lifter pre load

Interesting. I'm wondering what the base circle diameter is of that cam. They're usually .050" smaller, meaning you'd need a .025" longer push rod. Stock is 7.385". Add .025" to that and you get 7.410". Other than custom order, aftermarket push rods come in .025" increments and 7.400" is the closest to that 7.410". You're at .040" longer than stock as if the cam's base circle is much more than .050" smaller than stock.

In chasing a light ticking only within a specific RPM range, I recently measured all of my lengths to zero lash and preloads. My four longest lengths to zero lash are tied at 7.28125". With the 7.350" push rods I'm running, that's .06875" preload. Going one step up to 7.375" would put those at .09375" preload.

I'm tempted to try it. I was looking at the two highest preloads of .100" thinking those were the source of my noise. I haven't ruled it that they aren't. But, maybe it's the four lowest ones. I could tackle it from both ends and get four longer rods and two shorter ones. As it sits, I have a .03125" spread between lowest and highest. Reducing the two with .100 to .075" and increasing the four with .06875" to .09375" would tighten that spread to only .01875". Lowest would be .075" and highest would be .09375". The rest would be .08125" and .0875".


Yeah... I'm not expecting you or anyone to actually absorb any of that.

 

[swathdiver]

Interesting. I'm wondering what the base circle diameter is of that cam. They're usually .050" smaller, meaning you'd need a .025" longer push rod. Stock is 7.385". Add .025" to that and you get 7.410". Other than custom order, aftermarket push rods come in .025" increments and 7.400" is the closest to that 7.410". You're at .040" longer than stock as if the cam's base circle is much more than .050" smaller than stock.

In chasing a light ticking only within a specific RPM range, I recently measured all of my lengths to zero lash and preloads. My four longest lengths to zero lash are tied at 7.28125". With the 7.350" push rods I'm running, that's .06875" preload. Going one step up to 7.375" would put those at .09375" preload.

I'm tempted to try it. I was looking at the two highest preloads of .100" thinking those were the source of my noise. I haven't ruled it that they aren't. But, maybe it's the four lowest ones. I cold tackle it from both ends and get four longer rods and two shorter ones. As it sits, I have a .03125" spread between lowest and highest. Reducing the two with .100 to .075" and increasing the four with .06875" to .09375" would tighten that spread to only .01875". Lowest would be .075" and highest would be .09375". The rest would be .08125" and .0875".


Yeah... I'm not expecting you or anyone to actually absorb any of that.

You seem like an excellent candidate for adjustable pushrods or rockers!

 

[George B]

Interesting. I'm wondering what the base circle diameter is of that cam. They're usually .050" smaller, meaning you'd need a .025" longer push rod. Stock is 7.385". Add .025" to that and you get 7.410". Other than custom order, aftermarket push rods come in .025" increments and 7.400" is the closest to that 7.410". You're at .040" longer than stock as if the cam's base circle is much more than .050" smaller than stock.

In chasing a light ticking only within a specific RPM range, I recently measured all of my lengths to zero lash and preloads. My four longest lengths to zero lash are tied at 7.28125". With the 7.350" push rods I'm running, that's .06875" preload. Going one step up to 7.375" would put those at .09375" preload.

I'm tempted to try it. I was looking at the two highest preloads of .100" thinking those were the source of my noise. I haven't ruled it that they aren't. But, maybe it's the four lowest ones. I cold tackle it from both ends and get four longer rods and two shorter ones. As it sits, I have a .03125" spread between lowest and highest. Reducing the two with .100 to .075" and increasing the four with .06875" to .09375" would tighten that spread to only .01875". Lowest would be .075" and highest would be .09375". The rest would be .08125" and .0875".


Yeah... I'm not expecting you or anyone to actually absorb any of that.

I’m tryn…