318-340 rods query

Postby Goldenblack440 » 01 Nov 2009 15:14

hi, does anyone familiar with SB rod Part #s know what i should have here?

I have just pulled down a 318, it was a late model replacement engine (cast 1984 and assembled 1993) and the rods are part # 3418645 (pressed pin and cast crank)

The 1971 340 i have just pulled apart has the same rods but full floating pins as 340's do. It is a forged steel crank engine.

I have a set of 340 rods (full floating) i bought off ebay, along with another set of 318 rods, they are all the same 3418645 part number.

i thought that 340 had a heavier rod with a different part number? I know the 360 does.

Anyone with a book that tells what the part numbers should be for which engine, or if they changed through the years?

Thanks, steve
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Postby dave-r » 01 Nov 2009 16:42

My old small block books only cover engines up to the late 1970s but they suggest the "495" rod with floating pin for street and occasional high rpm use.

For more serious high rpm use such as racing they suggest the "641" rod with floating pin.

Don't know if that is any use to you but that is the only small block rod info I have.
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Postby Jon » 02 Nov 2009 2:29

I have some spare 340 rods from a 68 motor in the attic. I'll check the numbers tomorrow.
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Postby Goldenblack440 » 02 Nov 2009 11:45

Dave: those numbers...are they the last three numbers of the same part number, eg 3418-641, 3418-495, etc?

I know the early 273 also had full floating rods, bu these were very light rods. (an often passed over engine, the sweet little revver 273)

Jon: Thanks for that.
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Postby dave-r » 02 Nov 2009 11:56

Goldenblack440 wrote:Dave: those numbers...are they the last three numbers of the same part number, eg 3418-641, 3418-495, etc?


Last three of part numbers. The rest of the number may be the same but not always. Mopar guys tend to refer to parts by their last three digits. Such as "906 Heads".
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Postby Jon » 03 Nov 2009 23:08

The rods from the 68 short block 340 w/steel crank are 2899496. On the other side reads DF9MS 3049.

Just for grins I found an old (stock type forging) connecting rod with the direct connection part number P-4120558. :s004:
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Postby Goldenblack440 » 04 Nov 2009 6:12

Thanks for looking for me Jon, more numbers to add to the confusion eh? Looks like they had lots of part numbers over the years. BTW, just been looking at the Summit Racing site. They have some great prices on pistons, piston ring sets and Mr Gasket complete overhaul gasket kits ($42 !) for SB Mopar. 318 re-reing kits only $181 includes hyper-eutectic pictons and Moly rings, gasket kits and bearings. Have more pistons than Mancini for better prices for 340 engines too.
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Postby Goldenblack440 » 05 Nov 2009 14:50

Jon, your rod makes sense. Just found this info:

Yr, engine, pin type, part number, forging number
64-71, 273/318, Floating, 2406785, 1518699
72-73, 318, Floating, 2899495, 2899496
74-86, 318, Pressed, 3751015, 3418645
68-73, 340, Floating, 2899495, 2899496
71-86, 360, Pressed, 3751015, 3418645


So yours is the HD version of the 495. Apparently too, all 318 after 74 had the heavy duyt rod, and that Chrysler started consolidating parts after the 360, probably and sensibly to save costs.

I think with technology now though, a wiser choice would be the new light and strong rods. There are some fantastic prices on name brand I beams -Mancini have some Eagle I beams for under $300 and i bought some SCAT rods recently for a touch over $300. Very light, already weight matched and resized with ARP 2000 bolts, ready to bolt in. You do pay considerably more for H beam though.
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Postby dave-r » 05 Nov 2009 15:02

Oh well. There is that "495" rod mentioned in my book. The other one will be a MP aftermarket race rod.
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Postby Jon » 05 Nov 2009 16:01

More good detective work there Steve. I think it wise to go with an aftermarket if you plan to rev the motor above 6k. I had problems with both the stock 340 road and the Direct connection (shot peen-ed, magnafluxed, polished) "P" part. Missing shifts didn't help matters much for sure. :s023:
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Postby Goldenblack440 » 06 Nov 2009 15:24

Jon wrote:I had problems with both the stock 340 road and the Direct connection (shot peen-ed, magnafluxed, polished) "P" part. Missing shifts didn't help matters much for sure. :s023:


oh dear, my imagination is filling in the missing words from that sad story.
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