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Mercruiser Marine 350 block casting # identification

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Old Jan 12, 2001 | 11:48 AM
  #1  
G92Joe's Avatar
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From: Cromwell, CT 06416
Mercruiser Marine 350 block casting # identification

I have a 350 short block assembly with a casting #8970014. Other casting numbers appearing on the block are G2S 72, T3, and OONV2. The person I received it from claimed it was originally a Mercruiser marine engine.
Does anyone know if this particular block is any different than other 350 automotive blocks? I've heard the cylinder walls may be cast thicker, heavy-duty (pink?) rods are used, but the pistons and crank are cast.
I removed the oil pan, and confirmed it is a 2-bolt main configuration. Any guesses that this short block would hold up to 450+ hp as-is?
Thanks, Joe.
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Old Jan 12, 2001 | 12:16 PM
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RB83L69's Avatar
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
I could be wrong, but I'd bet that's 3970014, which is a typical common generic 2-piece rear-main-seal 350 casting dating back to the 70s and used for many years. I've had more than one block with that #. Some were fitted with 4-bolt caps, like many of the 3970010s were.

There's nothing special about that casting at all, no thicker walls or any such thing. It may be one of the high-nickel-content ones, I'm not sure about that, but even that makes no particular difference to the output the block can support. In short, it is netiher particularly desirable, nor particularly undesirable. It's just an ordinary block.

For 450 HP, I would recommend a steel crank and forged pistons, because that is probably going to put the RPM range up to around 6000. That block is fine for that assuming that it has no other problems. If you intend to operate it beyond 6500 RPM regularly I'd suggest you get 4-bolt caps put in it.

The rods are almost certainly not the "pink" ones, AFAIK those were never put in any production motor but only in the HP crate motors or over the counter as parts. THey may however be X rods, which are one of the best production-line motor versions around. They will work well at low HP like 450 with just new rod bolts like ARPs and a rework.

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"So many Mustangs, so little time..."

[This message has been edited by RB83L69 (edited January 12, 2001).]
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