318 ???.

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barracudadave67

barracudadave67

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Hello
I am working on a 66 Dart GT, it has a tired 273 2bbl in it. When I am done with the body, I plan on installing a different motor.
Here is my question.... What kind of crank is in an original, unmolested 69 318 2bbl, that has 89000 original miles on it,,,,,? I thought I remember reading somewhere that all the small blocks up to a certain year had forged cranks, is this so,,,,??

I was thinking of rebuilding the 318 for a nice street motor. If not I have a couple 340 blocks around also. The 318 is the original motor from my 69 B-Cuda, that I'm the 3rd owner of. A built up 340 street motor resides in it now. I also have a few cranks around here some place, but can't remember what they are as far as cast, or forged.

Thanks alot you guys. I love this place.
barracudadave67
 
The 273 has a forged crank in it and can be used in a 318. Drops right in.
 
forged or cast, the 318 is a tough crank. Unless you are doing something serious with the engine, no need to bother worrying about the crank.
 
While 273,318 and 340 cranks will interchange, there is the necessity of rebalancing everything. But a bigger issue is the converter problem that's been discussed on several occasions recently. The older 273 cranks have a small register for the small nose of the converter to fit into. Going to a newer ('68+) crank or engine will require a custom converter (spline count is different so they don't interchange) or a reducer ring for the older converter to properly fit into the newer crank/engine.
 
No, not all 273 cranks are forged. In '68, they were cast. My son and I just pulled one out of a supposedly unmolested '68 273 last year. (Put it in his 340.) The 318's would be in the same boat, except for some truck 318 cranks that stayed forged.

I suspect that the change in the crank register size is concurrent with the change to cast cranks. And if you want to tell the difference, you can search for threads here about how to tell cast versus forged.

For the OP, I would not worry over the cast versus forged issue for a mild to moderate street 318. My son and I put the '68 cast 273 crank in his 340 build last year, and that is a 375 HP or higher build, with a lot of low RPM torque for the street. (The only modifier that helped with that HP rating is light rods and pistons.) The general concensus is the cast cranks good for 400 HP or more, like Willrun318 indicates.

Note that your 273 and 318 cranks all interchange as far as balance, as long as you keep the pins and pistons together. Edit to correct: Keep the correct year pistons and pins and rods together. The 340 is the same crank, but is modified to balance with the 340's heavier rod and piston assemblies.
- So swapping 273 and 318 requires no re-balance.
- But the 340 crank will not balance with the 273 or 318 piston+rod assemblies (or vice versa) without rebalancing the crank.
- Balancing a 273 or 318 crank for the ORIGINAL 340 piston+rod assemblies is not the easiest thing to do. Balancing 273 or 318 cranks with lighter 340 piston+ rod assemblies is a snap.
 
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Unless you are building a 500 hp monster, what the crank "is" is inconsequential. Cast or forged
 
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