Aggressive Cam Lobe Ramps causing header ping?
 

This is long but I thought I would throw it out to limit the questions :)

Working on a built 360 fuel injected with Eddy Heads lightly ported, M1 intake, etc... Forged internals at 10.1 CR.
Camshaft is a Comp custom grind 218 / 224 cut on a 114 LSA installed at 110. Lift is .55 on both sides and the HL lobe profile was used to maximize the .904 tappet. Nothing radical here.

Valve train has normal (acceptable) noise for these ramps IMO.

Motor has Stans Headers and are very nice and heavy walled.

I did NOT build this so im trouble shooting someone elses work. However the individual who did is a good builder. Assuming he screwed up (although can happen) is not likely. Im not even sure something is wrong here.

Here's the issue. At idle there is excessive header ping in the pipes. I hate saying "ping" but im not sure what to call it. Not detonation. It was always explained to me from my teachers back in the day that the aggressive ramps will open the valve while there is still significant combustion occurring in the cylinder. EV open and the pressure hits the pipe. This will cause a snap or ping? Not sure if this is correct so chime in if you can explain this better please. Or if i am wrong, correct me please. This is not overlap noise.

I shot all the pipes with the heat gun they are all within 10-15 degrees and normal. Nothing lean. Compression excellent. I welded in multiple wide band sensors in both side at the collectors and down stream. We are 14.7 +-.1 at idle and cruise and dead nuts on at 12.8 at wot. Tip in goes slightly fat but nothing we cant tune out later. Making 330+ at the wheels. Super flat torque curve.

Ive used similar grinds before and this is spot on for power from my experience.

He installed an X pipe and the snap and ping was so loud in the X that I took it out. Yes, the X is loud but this was ridiculous. Ive heard the "ping" sometimes in cheap thin walled headers but not in the top line ones.

Zero exhaust leaks, water temp a steady 180 ish, Vacuum excellent, fuel sync at zero and tried at +2 and +4. +4 added HP but caused stumble of idle, so back at zero. Idle at 780 and very strong.

Ive have NOT used this HL lobe but have used the XE and XFI profiles. They make a little noise but not like this.

Is this an lobe by product? Ideas, suggestions?

Thanks all. Merry Christmas!

No expert here but what is your Exhaust Valve Opening event?

I am not sure that it is not just the long tube lovely header sound you are hearing. I would call it a rattling can noise myself and yes I believe an X pipe will make it louder.

Thanks for the replies!! I'm no expert either, I know just enough to get myself in trouble:) Keep the ideas coming I appreciate this.

EVO is 46 ( However, I haven't confirmed physically) For stock rod length I have always stayed under 55 on design and been happy.

You thinking pull front and check installed ceterline to confirm? When it was explained to me I thought same thing. The HP and Torque number are spot on for peaks and i had to bump his limiter as it was still making increased power at 5500rpm and the off line torque is really tight. So I opted to save the labor since it wasn't symptomatic. But i may do this just to satisfy my curiosity.

As for header rattle. I thought same thing. Appreciate the reply. I have heard headers that typically rattle but this is louder and then add in the fact that Stan uses thick tube and it has me somewhat curious..

Hmm......

I think this is probably more a matter of compression. "Back then" I remember ALL the Mopars I owned had "header tink" tinkety tinkety tinkety. This was stock RR 383 and later sixpack, as well as a stock 340 with headers. All factory 10 "ish" compression.

My low compression 360 doesn't do that, and frankly, I'm a little depressed about it. Might be the ($#$%%#@) alcoholic gas, too.

I wouldn't jump to disassembly to check. On your card does it give a height at what inches for your EVO. A couple I have used like a 284+292 are listed at .006", 70+80 EVO, BBDC. That cam looks beautiful and not very agressive I can't see how that profile could be considered agressive with those lifts and durations. With the increased LSA these types of problems should be lessened. I'm at a loss.

Personally, I like the set up as is. Cam is sized right and makes good power on a nice curve. And with the mufflers ( or lack of:) I dont know how the heck he can here the noise... but its there..

At .006 EVO is 72 on the card. Seems fine on paper. As to the "actual" event..? Dont know...

I'm secretly wondering if installer of the cam added advance during install to comps already built in +4 unknowingly??

I have chased bad lobes, bent PR etc... But any of you guys ever had a cam over advanced? What were the symptoms?

Can you post a sound bite? I'd like to hear it....

:hello: I agree thats a great suggestion Silverick

Sound clip? We just got rid of the rotary phone in the garage :) Sound clips? Ha..

I can maybe get one of the kids to do that and see if we can figure it out. I cant even do the real smilies.... Sorry. My tech skills are very limited... but i should prob figure out how to do that stuff anyway.

Currently onto a 5.0 rear main seal....... O happy day:(

I have looked at some old literature I havn't looked at in some time because you really got me thinking. The only problems I found for an over advanced cam are piston to valve clearance reduced with a risk of contact or loss of power. Both of these don't appear to be showing up as you've got good power and a valve would show up and reduce power aswell. Again I'm at a loss, possibly when the pipes soot up a bit the noise will be reduced.

Thank you for looking at that literature. I appreciate that.

The headers are brand new and pipes are brand new. Perhaps its the "industrial steel coating" they come with? When you said, "soot" you got me thinking. I wonder if this things snaps like crazy when its shut off. Find out tomorrow.

One thing I noticed is the intake was loaded with carbon? I do mostly fuel injected stuff these days and it masks some of the older "reversion" symptoms. This intake is 30 days old and caked... Looks like there was 100K on this intake.

Now I need to read up on "reversion" Ug!!!!

Only other symptom is an ever so slight low volume but deep burp at the tail pipe. If you didn't know that healthy overlap sound you would swear its normal. This isn't normal.

I thought bad injector, heavy resistance in the wire, gap, etc... This thing scoots when you hit it so its rpm dependent. Or closed loop dependent.

Threw the Snap on and got misfires all over cylinder 1 and 2. Swapped injectors and plugs from 7 and 8 with them and threw on overkill 8.8 wires from the shop. Re loaded tune and drove. No issues. Still runs great.

Got misfires all over cylinder 1 and 2 after the swap? In the course of a 2 minute idle period Snap On recorded 100+

O happy day........

Think he will notice if I sneak a Holley on this beast??

Does that burp sound like a puff sound sorta inbetween the da-da-ta-da-das, if you know what I mean. Exhaust valve seal? What does a compression test say?

YES!!! Exactly what it sounds like. Your description nails it!!

He said he did CR and he is pretty good usually. I will redo.

How the heck did you get EV seal from "puff". That's scary good..

Just good clean livin' I guess. Just showed my son this and he agrees on the scary part, not so much on the good. He's a real funny guy.