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Re: 340 crank in a 318 from factory?
[Re: Supercuda]
#910316
01/23/11 04:14 PM
01/23/11 04:14 PM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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273 and 318 used the same cranks, the forged cranks used in them were NOT drilled in the journals. They both were balanced for the same bob weights and used the same rods and the 273 had a heavier wrist pin to make up for the lighter pistons so they could use the same balance factor. The 340 used a much heavier piston and rod so it required a lighter rod journal to balance it internally even with the forged crank, that is the reason the crank pins had lightening holes drilled in them ONLY in the 340. The balancers for all 3 of those motors was the same any given year until the 340 went cast crank, the cast crank just was not heavy enough to balance internally useing the stock heavy pistons and rods even though the cast crank 273 and 318 could still be balanced internally with the cast crank, they just started drilling holes in the cast crank pin so the 273 and 318 could internally balance.
Bottom line, if it is forged and has holes in the crank pin it is from a 340, if there are not lightening holes in the crank pin than it is from a 273-318. All cast crank had the lightening holes in the crank pins weather 273 318 or 340.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 340 crank in a 318 from factory?
[Re: HotRodDave]
#910319
01/23/11 09:25 PM
01/23/11 09:25 PM
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Joined: Jan 2003
Posts: 1,072
The Sunny Shuswap
dodgefarmer
super stock
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super stock
Joined: Jan 2003
Posts: 1,072
The Sunny Shuswap
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Quote:
273 and 318 used the same cranks, the forged cranks used in them were NOT drilled in the journals. They both were balanced for the same bob weights and used the same rods and the 273 had a heavier wrist pin to make up for the lighter pistons so they could use the same balance factor. The 340 used a much heavier piston and rod so it required a lighter rod journal to balance it internally even with the forged crank, that is the reason the crank pins had lightening holes drilled in them ONLY in the 340. The balancers for all 3 of those motors was the same any given year until the 340 went cast crank, the cast crank just was not heavy enough to balance internally useing the stock heavy pistons and rods even though the cast crank 273 and 318 could still be balanced internally with the cast crank, they just started drilling holes in the cast crank pin so the 273 and 318 could internally balance.
Bottom line, if it is forged and has holes in the crank pin it is from a 340, if there are not lightening holes in the crank pin than it is from a 273-318. All cast crank had the lightening holes in the crank pins weather 273 318 or 340.
I have a 1969 273 (marine engine supposedly) crank that is through drilled, and extensively drilled on the counterweights to achieve balance.
Randy
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Re: 340 crank in a 318 from factory?
[Re: dodgefarmer]
#910320
01/23/11 09:46 PM
01/23/11 09:46 PM
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Joined: Jan 2003
Posts: 8,940
Holly/MI
Dean_Kuzluzski
master
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master
Joined: Jan 2003
Posts: 8,940
Holly/MI
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Correct me if I'm wrong..........
A casting number is the raw piece, unmachined..........
The p/n is then assigned when the part is modified/machined to the required spec'd per the application that the engineer created it for.
I'm saying this to inform some that haven't seen the distinction.
So, a given crank casting number could apply to either a 318/273 or 340 depending on how it was machined and the p/n assigned.
At, that's how it went when I worked for a competitor.
R.I.P.- Gary "Coop" Davis 02/09/68-05/13/04
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