That's making my brain squeak; I can't work out how new bolts would distort the rods and caps differently to used bolts. I'm not doubting you, just not following. Splain me?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

When ARP bolts get pressed in, they fit much tighter into the connecting rod. Sometimes the edge of the new bolts hit the side of the connecting rod and cause a little interference before they get fully seating. The extra tightness and interference is enough to distort hole and big end of the connecting rod. We are talking a couple thousandths of an inch probably. But when you have .002 clearance and the area at the parting line is distorted .002, you now have zero clearance at that point. Zero clearance, causes lack of lubricant at that point, which causes heat, which cause bearing failure. Or in my case a broken rod.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Yessir, re-size w/ARPs is a must for Me, no matter what engine We're talking...
There's another re-size needed for those with AARP, usually wardrobe related, luckily My skinny ass doesn't require that....

I had a set of 198 rods that were ruined by the machine shop. They resized the big end then they installed the ARP bolts, instead of installing the bolts first. The distortion was visible to the eye.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Found engine rebuild parts list. Yes, Mr. Rick ARP bolts were use in the rebuild. Not sure if the con-rods were resized. But by the comments here, they must have been. Called engine shop to get more info, closed for the long weekend. Business must be good. Thank y'all for the help with my stand pipe question. Doesn't seem to be the main cause for the rod knock. Tear down will reveal much. To be continued...

Tear down will reveal very heavy wear at the parting line if they were not.
Not sure I follow?

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Using ARP's the machine shop either resized the con-rods on purpose or accident. Admittedly that's presumptuous on my part. But not knowing gnaws at my tranquillity.

Here is what I have measured in inches.
On a Mopar Performance Rod Bolt (P4120097)
Under the head : .3915-.3920
Body Shank or Body : .388

ARP 142-001
Under the head : .394
Body or Shank : .388

I spoke to Tech at ARP and they said the rod big end needs a .392-.393 hole for the area under the bolt head.

Seems to be close, but the only set of ARP bolts I ever tried to install would not go in with normal force.
So I went back to MP.

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Hyper_pak

I have put in 3 or 4 sets. All were tight going in. Not snug, not tight, but real tight. First set I put in Ryan's Dart and never had them resized. It ran 50,000 + miles of very hard driving without any issue. I put a set in my 1st big bore engine and it only ran for 4 or 5 races and overheated the bearing and broke a rod/cap and destroyed the engine.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

The ARP bolts that were installed in my 198 rods were so tight they actually deformed the big end adjacent to the bolt. It was actually visible. I had heard ARP had temporarily discontinued the Slant six bolts doe to some issues. I did some checking and the factory rod bolts for the slant six, and the small block are the same. So You should be able to use the ARP small block bolts and have some extra's.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I would call ARP and get the tech information before buying the small block bolts.

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Hyper_pak

Years ago, I had an oil change place change the oil in my '65 Dart. When they got done, they had used generic oil and a generic oil filter. The next day, when I started the car, there was a knock.

In those days I was running the Motorcraft version of the FRAM PH8A. So i replaced the generic filter with the Motorcraft version and the knock went away.

Oil filters do matter. I always run the "large" filters and I always have a stand pipe on the pump.

Up-date, pulled one plug wire at a time to try isolate knock. Only made knock worse. Now thinking loose oil pick-up, main cap bearing? Time to pull the engine. Removed the easy bits. Got to flex plate bolts. They were tight but not real tight. Not too sure torque spec for them, 60 ft/lbs? Anyways one had some 'discoloration/scratches' on it. (see pic) That 'could' be the knock. Not sure how to proceed. Reassemble, torquing flex plate in proper sequence and hope. Finish pulling engine and tear down.

PS. either my laptops are jankie or the site is. Alot of posts have missing text.

The site is having issues. It is being worked on.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

A cracked flex plate makes a noise like a rod knock.
Loose bolts might also.

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Hyper_pak