Knock/rattle at lowish rpm. 455 *teardown/rebuild pg5*

Good call on the snap ring.

 

Doesn't look too bad, it's more than I like to see but if you want to feel better just cut open a filter from a new car. Dirty engine plants cause a lot of debris!

 

Those do look like steel chips vs iron particles, such as rings would be

 

Doesn't look too bad!!!!!
I still have some Chevy lifters from a friends motor that popped the clips out and the push rod cup got beat up so if these where Buick lifters you would be fine with reusing them?

 

Only one small piece was magnetic. Big bummer is that my Holley Sniper EFI just completely died, and its gonna be several weeks before it comes back from Holley. Disappointing, to say the least :/

 

I wouldn't hesitate to use the time to tear it down for inspection.

 

I had a few lifters fail on me when my engine was fresh. Clips broke and cups/springs popped out, all sorts of issues. It's well documented on my build thread.

Anyway, I never got all the pieces out. Fished out what I could, placed an extremely strong rare earth magnet (meant for hanging firearms) on the oil pan for good, and about 6k miles later no issues! (Knock on wood). If you caught it before too much damage could be done, you may be alright

 

In fairness, I pinched the handheld wire when I closed the hood. Had it out while I was troubleshooting, closed the hood and pinched it...kaput. Hopefully they will take care of me

 

Got the sniper re-installed after I took a month long work trip. Car fired right up, sounds great at idle and rev's cleanly in park. A quick drive through the gears, the noise is definitely load based. I can hold the car in 1st and gradually run up with no issue, or downshift without any load and it sounds fine. Once I give it more than gentle throttle, it rattles away.

Frustrated. :/

 

The timing is set per the power timing instructions found in the sticky, with the crane springs and adjustable vacuum can. I went one step less agressive on the springs, disconnected and plugged the vacuum advance, and disconnected/plugged the TH400 modulator line and the HVAC control vac line. No change.

 

What is "stock compression"?
That's a pretty tiny cam depending on your compression, potentially making things worse.
It does sound like it's still too fast of a curve with too much timing.
Perchance is this recently machined?
Sharp edge left around the combustion chambers make these timing curves impossible to do, even if the dynamic compression is safe on paper.

 

Comments on 'the wrist pins being the culprit' following the piston installation being backwards...
At face value of that comment, the wrist pins are not at fault.
Wrist pin bores are offset towards one side to keep the piston skirts from slapping the bores.
Reverse installation creates a piston slap, which is usually only just noisy...at least short term.
If there was damage to those wrist pins and the machine shop told you that...there was a mistruth to cover up bigger problems.

 

If you have no noise when revin up out of gear , but do under load then the motor is knocking either due to too much timing, too much cylinder pressure or a combo of both!
While knocking your pounding the rod bearings out of the motor little by little dependant on the revs and throttle opening!

 

A weath of helpful and wise folks on here, I hope you are able to discover the culprit and get back to enjoying your car Steven.
Best of luck

 

Interesting... your initial comments were that it was at 1700 rpm, regardless if you snapped the throttle open, or gently crept up on the rpm. Now it sounds like your saying it's only with higher load on the engine.

The first symptom is describing something mechanical.. excessive clearance or unwanted contact of internal parts.. the latest description is of a noise that only happens under load. While this still can be mechanical, that type of symptom often is a pinging noise due to detonation.

To further test, your initial and total mechanical advance numbers look fine, but I am wondering about how fast the curve is.

If your putting it all in by 2500, then try this... slow the curve down, and have it all in by 4500.

Part throttle detonation can be the hardest to solve. You need to make a bigger swing at this. If you have an old stock distributor around, put the springs in from that.

JW

 

The engine is very recently rebuilt, unfortunately it changed hands a few times before I bought it that way and I know not much about it. All parts other than the carb appear stock or stock replacement, and a compression test shows 160-170.
I do have the ta-212, Holley sniper and a pertronix ignitor with coil for the non-stock parts now

 

Thats the way I'm leaning. I'll pull some more timing out this afternoon

 

Correct, unfortunately its fairly hilly where I live, and I didnt give it quite enough diagnosis. Now I find that i can be above where the noise usually starts and drop down a gear, without the rattle happening.

I was running the crane blue/yellow springs (all in by 2600), I just swapped the blue/blue in (in by 3200), and I'll take a few more degrees of initial out as well. Thanks for the input everyone!

 

New NGK UR4 gapped at .40, the blue springs, and its still there. I have the stock springs around, I'll try those next. I wonder if the pertronix has anything to do with this