If this is a double post, please forgive. I tried to send from my android but can't find it.

I bought my project engine without any idea what year it is. The ID number on the deck has been milled off. Based on the 5 freeze plugs and the forged crank, I have been ordering parts for a 1969 Dart because I had read here on another post that all slants up to 1975 had forged cranks. My crank certainly sounds forged. It rings like a church bell when struck lightly on a counterweight. .
I just got a set of rod bearings from RockAuto and they are much more narrow than the rod journals. They are at least .030 shy of the fillets on the rods on each side. I read that the main bearings for the forged crank are wider than those for a cast crank. I haven't received the main bearings yet. Are the rod journals for a forged crank also wider than the cast ones?

Thanks, Bernie

Yes they are.

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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

Rock auto's listings for rod and main slant six bearings are not correct in most cases. I am also finding the same problem with other online catalogs. What part number and brand bearings did you receive?

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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

The invoice from Rockauto says:

Mahle/Clevite CLE CB606G10 (the crank is .010 under)


The Mahle box says:

Mahle CB-606G-10
2375CP10
0270675 10433

That part number seems like a forged rod bearing.
Post a picture of the bearing shell in your rod cap or in the rod journal.

I think 0.030" in from the fillet is not anything to worry about.

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http://www.youtube.com/hyperpack

Cannot seem to upload from my phone. I may be wrong on my estimate of the difference in size but it is not a reasonable amount. I have built a couple of engines and never saw a bearing that wasn't the same width as the journal it runs on.

The bearing will not be as wide as the crank journal. See how it fits in the rod. If you notice the rod bore has a camphor on the edge. The bearing should fit in the rod bore, and not be as "overhang" the camphor. That part number CB606G is the correct part number for the forged crank.

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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

So the bearing shells will not be as wide as the rod journal? Forgive my curiosity, but what keeps the bearing from "walking" side to side in the journal? Just the tangs? Why would they design a journal wider than the bearing? Wouldn't this cause a "groove" in the rod journal as wear occurs? These shells do not overhang the chamfer, they don't get anywhere close to the chamfer.

Don't worry about the "tang" it is only for locating the bearing. It has nothing to do with preventing the bearing from moving. The "crush" of the rod housing prevents the bearing from moving. If the bearing is wearing a groove in the crank there is a problem. The bearing should not ride on the crank journal. There should always be a cushion of oil between the bearing and the crank. If you have a micrometer or vernier caliper, measure the width of the bearing. It should be .984 wide. That is the actual measurement of a Michigan 77 CB-606G bearing. I don't have any cast crank bearings to check.

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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

The bearings measure as you say. Thank you sir. I will concede to your knowledge.
Would love to talk to the engineer that designed a bearing surface approximately .100 wider than the bearing it rides on.

Most of the rods I have seen have this feature, at least old Mopar engines, US V8s, etc. Probably it has to do with giving ultimate support to the bearing so there is no concentrated force right at the edge of the bearing shell and/or the rod surface. It could also have to do with holding a reservoir of oil there after it exits the bearing shells in case oil supply is temporarily interrupted. Heat dissipation at edges is another idea. I do not know, but I know there is a good reason...

Lou

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Home of Slant6-powered fun machines since 1988

If I never talk to another engineer that would be fine with me!

_________________
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