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502 crank question

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Old 04-18-2012, 02:19 PM
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Default 502 crank question

Does anyone know if the genIV carbed 390h.p. 502 has a forged crank from the factory or not? All my searching said yes, but I want to be 100% sure. Thanks in advance.
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Old 04-18-2012, 02:58 PM
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ob,
Someone is probably going to proove me worng on this, but I didn't think there was such a thing as a cast 502 crank so I would have to say that yours is definitely forged ?

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Old 04-18-2012, 04:20 PM
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Your 390/502 has a forged crank.


There's no such thing as a cast 502 crank (as supplied in a motor sourced from GM). All cranks that came from GM in a 502 are forged. All pistons that came from GM in a 502 are forged (but there are several variations). All rods that came from GM in a 502 are forged and have 7/16 bolts. All heads that came from GM on a marine 502 are rectangular port (some crate motors had alternate heads).

There's no such think as a Gen IV 502. The 396/402/427/454/502 Std Deck GM Big Block is a MkIV thru around 1990, when the Gen5 was released.

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Old 04-18-2012, 08:37 PM
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Quote:
Originally Posted by mcollinstn View Post
Your 390/502 has a forged crank.


There's no such thing as a cast 502 crank (as supplied in a motor sourced from GM). All cranks that came from GM in a 502 are forged. All pistons that came from GM in a 502 are forged (but there are several variations). All rods that came from GM in a 502 are forged and have 7/16 bolts. All heads that came from GM on a marine 502 are rectangular port (some crate motors had alternate heads).

There's no such think as a Gen IV 502. The 396/402/427/454/502 Std Deck GM Big Block is a MkIV thru around 1990, when the Gen5 was released.

MC
MC, All good information. I think he was calling the MkIV block the Gen IV. To further your post, in 1998 the Gen 6 block was brought into production by GM. My Merc 7.4L
330P motor was a Gen 6 block. Along with:
http://www.crateenginedepot.com/ZZ-5...P9419C604.aspx
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Old 04-18-2012, 08:40 PM
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Thanks for the response guys. All the searching I did, I couldnt find a cast crank either. I just wanted to double check before I purchased this engine. Again, thanks for the help.
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Old 04-18-2012, 08:43 PM
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Originally Posted by ROTAX454 View Post
MC, All good information. I think he was calling the MkIV block the Gen IV. To further your post, in 1998 the Gen 6 block was brought into production by GM. My Merc 7.4L
330P motor was a Gen 6 block. Along with:
http://www.crateenginedepot.com/ZZ-5...P9419C604.aspx
Rotax454,


You are correct. I was calling the mkIV the gen IV by mistake.
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