My son has a Stage 3 sloppy cam he installed in his LQ9 6.0L. The valves are tapping the pistons enough to make a noise but have not bent the valves. I made him take it back apart to check and there is a mark on all the pistons. Also all the valves have marks around the edge. I figured the full kit would provide everything he needed and didn't know I would need anything else. I checked to see when the intake was opening on the travel and it appears to be 40 BTDC.
Is that too soon? I'm trying to figure out if this is ok or if this needs either shorter push rods or cam timing changed. I did not watch him time the camshaft but assumed he did it correctly. I am trying to avoid taking it apart again. But what is the earliest these engines should ever open the valves?
Just for some reference, I've been an ASE L1 master tech for years. I have never gotten into tuning, it doesn't interest me too much. There are too many cars that are OEM that don't run right, I don't want to make my own problems! The only reason I say this is so anyone would know where I'm coming from.

 

OP: "The valves are tapping the pistons enough to make a noise but have not bent the valves"


........... You sure about that ?

 

Absolutely. I had one of my novice techs do this once before on a Traverse timing chain. Its probably the luckiest thing that can happen to you as a tech. But any idea of timing advance limit on that?

 

Clearly, you'll need a thicker head gasket.
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. Seriously though, Do you have any modelling CLAY? You can trial assemble the engine, with a strip of CLAY across the piston top valve relief(s) and carefully attempt rotation by hand, and then measure the resultant CLAY thickness to simulate piston to valve minimum clearance.
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Obviously, as an ASE Master Technician, you already knew alll that.

 

Wrong question. The "bigger" the cam, in general, the earlier it will open the intake. A stock truck cam opens almost at TDC; a "performance" cam will, in general, open the intake FAR earlier. Advancing any cam will of course also open the intake earlier.

You could try playing with the cam timing butt if you retard it very much the exh valves might end up with the same problem. I'd start with checking the timing set alignment; then if that's OK, the clay suggestion.

 

Obviously if I knew all that I wouldn't be on here. What are asking?

 

I'm just unsure of the maximum amount someone would be able to advance a cam. This 40 degrees seems high. But what is a real world value that will work? I agree with playing with the cam timing but am trying to avoid all that if possible.

 

Where did he buy the cam ?
could be an Amazon special ?

 

Sure you got that cam installed or checking it correctly?

Camshaft Specs:

• Cam Lift Intake: .350
• Cam Lift Exhaust: .350
• Valve Lift Intake: .595
• Valve Lift Exhaust: .595
• Adv. Duration Intake: 296°
• Adv. Duration Exhaust: 299°
• Duration @ .050 Cam Lift Intake: 238°
• Duration @ .050 Cam Lift Exhaust: 242°
• Intake Opens at: 11° BTC
• Intake Closes at: 47° ABC
• Exhaust Opens at: 57° BBC
• Exhaust Closes at: 5° ATC
• Camshaft Overlap: 73°
• Lobe Line Intake: 108°
• Lobe Line Exhaust: 116°
• Operating Power Range: 2,200-5,400 rpm