318 build up

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Then, someone has been welding the balance drilled holes in it. If a real enigne-shop has done it, that would be ok, I guess. But if someone did it at home.....[/QUOTE]

Arentbyou supposed to press in slugs made of mallory metal to rebalance??
 
JohnWayne said:
With futher investigations of the forged crank, I belive it came out of a 273. The casting numbers is very hard to see, but the two first ones is 21. According to my books that would be a early 273 crank.

The bearings do not look very good at it. A polish would not be enough. Then, someone has been welding the balance drilled holes in it. If a real enigne-shop has done it, that would be ok, I guess. But if someone did it at home.....
Click to expand...

Arentbyou supposed to press in slugs made of mallory metal to rebalance??
Click to expand...

Typically, yes, but only if you need more weight than a little bit of welding can't cure and naturally, that all depends on the parts chosen. Using light pistons like the KB 167s should work well with 273 light duty stuff, and it'll keep down the bobweight (less parasitic hp loss). I've received engines back from reputable shops with weld marks on the counterweights--cast and forged cranks alike...if they only need a couple grams, it's significantly cheaper to weld than buy/add the mallory. You should be able to tell if it was done correctly...if the welds look like a rack of dimes, you're good, if it looks like someone laid on blobs of slag, you might want to have that addressed.
 
moparmat2000 said:
Its gonna be awhile before i actually crack it apart and inspect everything, however with the .040" overbore KB flattops, and 65 cc head chambers it will put it around 324 cubic inches, and around 9.9 to 1 compression. Plenty of pop for a street engine.
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Do you have any cam choise yet?
 
From one source, the early 273 forged crank numbers are:
2268119 Manual trans
2463551 Auto trans
I suspect these numbers are later service replacement parts numbers, because this does not agree with this PN info which is from a FABO post for forged crank numbers:
2128278
2128869
2205700
These 3 above are probably the original forged crank PN's.

The later cast 273 crank (also used in the early 318s, I believe) was 2843699, per what I can find. But I do not know if this is the original or just a service PN.

FOR BALANCE:
I would consider using the early 273 crank and the 273/early318 rods for the following reason: If you are using the KB167 pistons, the total weight of the 273/early 318 rod plus the KB167 pin and piston, would be:

726 gr + 132 gr + 526 gr = 1384 gr

The stock 273 rod+pin+piston weight was 1479 gr for 4 bbl and 1476 gr for 2 bbl. So you would end up about 95 grams under the stock weight. Engine balancing would be easier as you would only be taking weight off of the crank, not adding it on. (And it may require less weight removal than balancing to the 318 crank, which may be cast for a heavier 318 rod+pin+piston weight combination. But I don't have the stock 318 piston weight to be sure of that.)

Now that I think about it, the later rods with a 758 gr weight, would add 32 grams to take you to around a 1416 gr total and the balance process would be even easier.

I do not know if the 1416 gr total weight is within balance limits for the 273 crank; it is 5% off from the stock 1478 gr 273 weight, so I suspect not; maybe someone can comment on this.
 
I have, in my collection, several sets of well used SBM rods, from the late 60s to mid 70s. Some are 318, some are early 340, and some are early 360. All have the same casting numbers. Some are bushed. Some are for pressed pins. I have not weighed any of them.
The point is, I like the full floating ones, mostly cause I can take them apart at home.They definitely appear more robust than the 273/early teener rods.
 
I've read the comments on the lighter rods..... those who have actually beat on them report success. The comments about them looking light have all been from those who have not ever used them. So I am concluding they are OK. But I am sure I will get an earful of how they failed now! If so, please state if you put in new rod bolts, how much HP or 1/4 miles times, etc., so some context can be had for any such failures.

From what I have read, the heavier rods are only about 32 grams more metal....so they can't be THAT much stronger.....
 
Ive run them in stock;273s and early teeners.No problems. But those engines barely break 4500rpm.I think they would be strong enough in their original application.I guess think is not right cause the Chrysler engineers must have more than thought about it.I have to wonder though,why they later switched to the heavier rods.
And I would worry about them, when trying to put the coals to them. Id hate to find out, with a lousy tune.And since I regularly visit 7200,I left them in the box.
If you grab one of each, I dunno,That little rod just dont feel like it wants to go.I just dont have the spare cash to build a second motor if it does let go.
Then again, if you look at those teeny rods in the 5.7 hemis.....I nearly fell over laughing the first time I saw those.Guys seem to be putting some good pressure on them tho.........
I thought Id offer that info, in case the OP had options. I certainly wouldnt rush out to buy new rods just yet.
This is of course just my opinion.
 
rumblefish360 said:
These questions are aweful rookie like.
New to this?
I believe you need to read a book or two.
How to rebuild and how to hit rod your small block MoPar would help you A LOT.

Cranks fit into the block.
The back of the crank is ether drilled for a manual trans or not.
If not drilled for a manual trans input shaft, have it machined.
The newly drilled pilot hole will need a bushing.
The manual trans input shaft needs that bushing.
Click to expand...

Yes, because when it comes to engines I´m kind of a rookie. Body and paint are my strong sides :)

I now reading a book every night before going to bed, How to hot rod your small block Mopar engine :)

And I´m learning all the time :cheers:
 
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