3.4L swap, all new components; what are the causaes of valve clatter when accelerating, most notable when engine is at operating temp?

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If you're sure it's actually valve clatter, and it's a pushrod engine, then it's possible that your hydraulic lifters aren't pumping up for some reason. Perhaps you're using the wrong viscosity oil. Another problem could be that your valve lash was set incorrectly.

Are you sure it's not pinging? I can't think of why valve noise would only happen while accelerating.

quote Originally posted by TopNotch: Are you sure it's not pinging? I can't think of why valve noise would only happen while accelerating.

X2

Valve clatter would be audible at idle. Often when using forged pistons, piston slap will occur and that too sounds like valve clatter. Another possibility is a bad cam but since you hear this only when accelerating put me down for detonation X3.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
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OK, pinging it is. At idle there is no issue, when the engine is cool there is no issue, while cruising there is no issue; nl on acceleration and only when the engine is at temp.

Booz, valve lash was set at stop + 1.5 turns.

So, what can cause the "pinging"? Timing? Fuel? etc....

3.4L PR motor, 2.8 heads, CompCams 240H Cam

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Peace!!

B2 OUT!!
86GT 3.4LProject

[This message has been edited by BAM-BAM (edited 08-30-2011).]

exhast leak perhaps??
my car makes a clicky clatter sound when accel. thats because i have an exhaust leak at the header. (cracked exhaust manifold)

quote Originally posted by BAM-BAM: ... valve lash was set at stop + 1.5 turns.

... and exactly what do you mean by "stop?" Sounds possible that your valves may be adjusted way too tight.

Concerning possible pinging: Is your EGR connected and functioning properly? Or did you remove it? The ECM advances the ignition timing when EGR is being commanded, and non-functioning EGR can lead to pinging at partial throttle. On the other hand, EGR-related pinging should cease as you approach full throttle, since EGR is discontinued at high throttle openings.

Other causes of pinging? Ignition timing set incorrectly (too much advance) ... high compression ratio (& low octane fuel) ... too-lean fuel mixture (low fuel pressure?) ... high combustion chamber temperatures ... combustion chamber deposits (unlikely on a new engine) ... incorrect spark plugs (heat range too hot).

[This message has been edited by Marvin McInnis (edited 08-30-2011).]

What ECM are you running and what code?

Your description also makes me think knocking. Does it make a diference if you are running 93 octane vs 87?

quote Originally posted by joshh44: exhast leak perhaps?? my car makes a clicky clatter sound when accel. thats because i have an exhaust leak at the header. (cracked exhaust manifold)

Generally exhaust leaks get quieter as the engine warms up because the parts expand into each other. Otherwise I would agree the noise is similar.

My vote is for detonation - Timing is off, poor fuel, EGR problem, Part throttle lean condition? I'v seen this problem on a 3.4 before. No matter how we timed it, it had a slight detonation or ping at part throttle under acceleration. If we pushed the throttle slightly past the point where it would ping, the ping went away. Thinking it has something to do with the stock 2.8 fuel maps in the ECM???? We had one of those "hot chips" in a different ECM installed but it seemed to ping under load regardless of the throttle position. I suppose maybe it could be the TPS? At that point in the throttle opening where it pings, maybe it's sending - or not sending the proper signal to the ECM? Also using 1.6 roller tip rockers but I do not think that would make a difference in detonation?

josh44- I just got the motor back in after changing the exhaust manifold gaskets (I had used the 3.4L gasket previously). There is absolutely no exhaust leak at this time .

Marvin- What I was refering to is tightening the rocker nuts until the "up-down" motion stops then an additional 1.5 turns. That is per just about every thread that I have read.

Also, regarding the EGR, I am throwing and EGR code and have yet to narrow it down. I am leaning toward the EGR control module. I just had the EGR off while changing gaskets and i could depress the valve, hold my finger over the vacuum port and the valve held the vac until I removed my finger then it snapped back. I have RD's stainless steel lines and all of vac ends fit correctly. I am also thinking that it may be timing related. A couple of weeks ago, I replaced the pick up coil and ICM and may have the timing a little to far advanced. I have just started hearing the ping recently (so thats very likely). I will also run the higher octane fuel, been running 88 or 89.

I thank you all for your input, it means alot to have such a diverse arena to draw from

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B2 OUT!!
86GT 3.4LProject

When its pinging (clatter when accellerating, expecially in high gear going up a grade) try using higher octane gas or retard the timing a few degrees.

quote Originally posted by BAM-BAM: What I was refering to is tightening the rocker nuts until the "up-down" motion stops then an additional 1.5 turns.

It's still not clear to me what you mean by "until the 'up-down' motion stops." If the pushrod is tight or will no longer move 'up-down' at all, then you've gone too far. Zero lash is the point where free play of the pushrod in the lifter socket suddenly drops to zero. An additional 1.5 turns from that zero-lash point is correct.

JazzMan's technique is probably the easiest and best way for most people to determine the zero-lash point:

"Don't use the spin-drag technique, that only works if you have lots and lots of experience and practice, or a surgeon's touch. Instead, pull the pushrod up so that the slack is taken out of the rocker arm and then wiggle the bottom of the pushrod side to side, like a blind man using a cane. You'll feel the "tap, tap" as the end of the pushrod taps either side of the lifter poppet recess. As you tighten the rocker nut you'll feel the distance decrease until suddenly it's gone. Remember, always pulling up, never pushing down. At this point you're at zero lash. Turn the rocker nut 1.5 times and you're done. Make sure the lifter is on the cam base circle, this is critical.

"... the idea is to get the poppet in the middle of its travel so that it has the best range of self-adjustment for various changing conditions in the motor such as thermal size changes (pushrods get longer as they warm up, for instance). ... 1.5 turns puts the poppet halfway down the lifter body."

[This message has been edited by Marvin McInnis (edited 08-31-2011).]

Ok, gotcha, that is what I was refering to. Just a little miscommunication. When the free play is at zero +1.5 turns. Sorry for the misque. This morning I drove it to work (82*) and it ran awesome, no exhaust leak and no pinging. This afternoon however, it is supposed to be 106* and I have a 35 mile drive home which should uncover any bugs that are hiding. I am inclined to think that my timing is off a bit. I will readjust it this afternoon/evening and see if there are any issues. I may retard it a couple degrees and see how that pans out (thanks Roger) .

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Peace!!

B2 OUT!!
86GT 3.4LProject