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I've ran into some confusion on a 327 lg journal crank as to if GM made a forged one. Mortec shows two different numbers. I spoke to a crank regrinder and he said Chevy never made a forged lg journal. I know they made sm journals as I have a few but I need a 327 lg crank and might go forged if in fact there is some available as I've seen several on Ebay. Thanks for the info.
Chuck
 

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Chuck If I am remembering correctly by the time GM went to the large journal 327 it was pretty much a sedate small block. Only came with a 2 bbl carb and put out about 200 hp. The 350 was the new hot rod small block and the same numbers the 327 used to produce was made a lot easier by the new 350 mouse. This may be the reason all the forged cranks are small journal.
 

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Thanks Phil, I also wondered if the 350 had something to do with the 327 crank confusion although I see the forged 327's for sale and cautious to buy one. What do you think about the 383 cranks on the market as I'm leaning towards a stroker?
Chuck
 

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Chevy stopped using their forged crankshafts cranks for the 327 about 1964 when they introduced the first cast iron ones. All forged 327 cranks made by GM are small journal. Only solid lifter motors got a forged crank after 65. The 350 came out in 1967 exclusively in the Camaro, and was released for production in all other vehicles for 1968 with a large journal (the 1967 350 was the first large journal motor). All small block engines made after 1967 were large journal and were made of cast iron unless it was for a high performance motor.

A 3.75" stroke will build more torque in the lower RPM's were it is needed on the street. A 3.25" stroke motor will build more peak horse power; but it does so only at extreme RPM's found normally while racing, not cruising on the street.

Big Dave
 

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Large Journal 327 "Steelies"

Heads up guys!!

Just finished a 100% factory original 327" SB unit for a '68 "Vette" restoration!

Large journal without a doubt AND "steel", the correct part number is in the post, "4672", and it's also "nitrided".

Thanks, Gary in N.Y.

P.S. I have a number of these L/J pieces "on-the-shelf" as original "rotating assemblies" with the forged 11:1 pistons, all these cranks are still std./std. They were also found in the "marine" environment! They fit the '68's and later units.
 
G

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someone can check my memory but i believe the 4672 IS a steel, but is a small journal crank.

not trying to argue, correct me if i'm wrong... i think i'm right though.


i've always liked 327's. i like the way they rev :D



Be Good !!! ;)
 

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Chevy stopped using their forged crankshafts cranks for the 327 about 1964 when they introduced the first cast iron ones. All forged 327 cranks made by GM are small journal. Only solid lifter motors got a forged crank after 65. The 350 came out in 1967 exclusively in the Camaro, and was released for production in all other vehicles for 1968 with a large journal (the 1967 350 was the first large journal motor). All small block engines made after 1967 were large journal and were made of cast iron unless it was for a high performance motor.

A 3.75" stroke will build more torque in the lower RPM's were it is needed on the street. A 3.25" stroke motor will build more peak horse power; but it does so only at extreme RPM's found normally while racing, not cruising on the street.

Big Dave
Here the only discrepency with that, I just bought a 1968 327 chevy, large journal forged crank, I beleive it is a steel crank, casting number 4672. It IS a forged crank, wide parting line, pings when tapped with a hammer. Did this come out of a corvette or camero SS? I have the entire motor(sb) if any stamped numbers would help.
 

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Here the only discrepency with that, I just bought a 1968 327 chevy, large journal forged crank, I beleive it is a steel crank, casting number 4672. It IS a forged crank, wide parting line, pings when tapped with a hammer. Did this come out of a corvette or camero SS? I have the entire motor(sb) if any stamped numbers would help.

According to a fellow by the name of Alan L. Colvin the crankshaft that bears casting number 3914672 was only made in 1968. It was a forged steel crank, but it was not a high performance part as used in a 300 plus horsepower 327 but instead it was found in C-40 through C-60 medium duty truck engines. So the crank is balanced for a heavy cast aluminum truck piston not a car piston so it will need to be rebalanced. It is a large journal crank.

Big Dave
 

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According to a fellow by the name of Alan L. Colvin the crankshaft that bears casting number 3914672 was only made in 1968. It was a forged steel crank, but it was not a high performance part as used in a 300 plus horsepower 327 but instead it was found in C-40 through C-60 medium duty truck engines. So the crank is balanced for a heavy cast aluminum truck piston not a car piston so it will need to be rebalanced. It is a large journal crank.

Big Dave
No sir, you misread. The casting number, complete is: 4672, not 3914672. Yes, they are two different cranks. Mine is the four digit 4672, which under casting numbers says its a lrg. journal 327 nodular iron crank. I do beleieve it to be steel, could be wrong. But beyond a shadow of a doubt it is forged! I bought the engine, shortblock complete, balanced rotating assembly. But my forged crank part number is 4672 on front counter weight.
 

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Ok, just checked the numbers and your crank is nodular iron not forged.

4672= 307/327 68-73 2.45/2.10 3.25 Stroke Nodular Iron

3914672= 327 2.45/2.10 3.25 Stroke Forged

Well, now I come up with this????.. I think we need a pic of this crank...

4672.......327.......forged..medium journal...3.25" stroke
 

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Ok, just checked the numbers and your crank is nodular iron not forged.

4672= 307/327 68-73 2.45/2.10 3.25 Stroke Nodular Iron

3914672= 327 2.45/2.10 3.25 Stroke Forged

Well, now I come up with this????.. I think we need a pic of this crank...

4672.......327.......forged..medium journal...3.25" stroke
This is correct: 4672.......327.......forged..medium journal...3.25" stroke I know this as the cast cranks have a thin casting line where the two halves of the mold met when the crank was cast in the foundry. My crankshaft, #4672, has a wide parting line, looking as though the thin line was pressed out or ground down, where the forging process mashes that thin parting line. In a John Lingenfelter book I have he also notes the forged cranks can be tapped with a hammer and make a "ping" sound as compared to a "dull" thud when doing the same on a cast crank. I have no doubt that the crank I have is a forged crank (ping), but many sources state that in post 64'-65' applications, the only forged 327 crank was used in HP applications (i.e. 375 HP 327 corvette engine). The cam is still in place, no numbers visible on nose of camshaft to verify the grind number,that is what I'm dying to find out. Paid $150 for the shortblock and the crank is a casting (unmachined sides have sandy texture, but appears to be steel I will post pics sometime tomorrow. Have a good one bud!
 

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This is correct: 4672.......327.......forged..medium journal...3.25" stroke I know this as the cast cranks have a thin casting line where the two halves of the mold met when the crank was cast in the foundry. My crankshaft, #4672, has a wide parting line, looking as though the thin line was pressed out or ground down, where the forging process mashes that thin parting line. In a John Lingenfelter book I have he also notes the forged cranks can be tapped with a hammer and make a "ping" sound as compared to a "dull" thud when doing the same on a cast crank. I have no doubt that the crank I have is a forged crank (ping), but many sources state that in post 64'-65' applications, the only forged 327 crank was used in HP applications (i.e. 375 HP 327 corvette engine). The cam is still in place, no numbers visible on nose of camshaft to verify the grind number,that is what I'm dying to find out. Paid $150 for the shortblock and the crank is a casting (unmachined sides have sandy texture, but appears to be steel I will post pics sometime tomorrow. Have a good one bud!
Im new to this site, so if you could, how do i upload pics from either my phone or my pc to this page so you can see the crank?
 

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