Extremely noisy lifters after cam swap (new LS7 lifters) 2008 SSV

[Pollushon]

So wait when was the pushrod loose under the rocker? Is this cam base circle stock size?

 

[MrPtnt]

The pushrod came loose last night, when the loud knocking noise stopped. It wasn't loose directly after the cam swap.

I havent measured the base circle, and now the cam is in the car. It is a vcm883 cam.

 

[Pollushon]

The 883 is over .600 lift so it's a safe assumption it has a smaller base circle. If so and the rest is stock your 7.4 are too short in theory. Your rods are likely slopping around and smacking the valvetrain around like its bitch.

Good luck pulling it down mate but in all honesty if you're not going to bother measuring your rods after a significant change there's really not much anyone can do aside guess.

 

[07GTS]

best to check clearances no matter what, my cam only has .597 lift and yet it still had PVC lucky my mechanic checks cos not all LS engines are the same there are anomalies, mine is rare and has the pistons reaching just over deck height causing the issue had to use some different head gaskets to make it right so i could use the cam

 

[MrPtnt]

Is there an easy way to test piston to valve clearance on these? I don't have solid lifters, which seems to be required for the clay method. Last time I turned the car over by hand and there wasn't any noticeable interference, but when I pull it all down, I would like to do it right.

 

[Pollushon]

Is there an easy way to test piston to valve clearance on these? I don't have solid lifters, which seems to be required for the clay method. Last time I turned the car over by hand and there wasn't any noticeable interference, but when I pull it all down, I would like to do it right.

Yes. When you pull the heads off you'll know. If it even touched a skerrick your piston tops will tell you.

 

[blackve76]

Is there an easy way to test piston to valve clearance on these? I don't have solid lifters, which seems to be required for the clay method. Last time I turned the car over by hand and there wasn't any noticeable interference, but when I pull it all down, I would like to do it right.

When I put my cam in I bought checker springs(small spring that doesn't collapse the lifter bucket) to ensure all was good and clay on piston top to measure clearence. Generally you will feel resistance when rotating engine over but you need 80thou intake and 100thou exhaust clearance to allow for heat expansion.

 

[07GTS]

get a little camera to put in the spark plug hole and u should be able to see any marks on the tops if they touched, or watch this and it will give u an idea

 

[MrPtnt]

So, I have measured the lifter pre-load on a few valves using a tool. I get about 7.3" length at zero lash, meaning my 7.4" pushrods would be giving me 0.100" preload.
Google seems to give differing opinions on what is correct preload, but 0.100" doesnt seem radical for LS7 lifters.

 

[Pollushon]

Oem recommended preload is in the middle of travel about 080. 100 is right on the limit 110 is safe max. That should be barely a half turn to 22ftlb which is why I said the turn method is unreliable if you got a full turn. I'd be sure to measure all rods as it only takes one out of whack to get things broken or noisy af.

Still doesn't add up if this thing is stock with a smaller base circle cam 7.4 actual (7.385) is the stock length rod. Your preload should be less than stock 080 in theory. What brand are your lifters?