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PhD in Procrastinology
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I found an ad on CL for a 1972 351. Guy said it's a "marine" block. What is the difference between that and other blocks, new and old?
 

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different freeze plugs and a backwards firing order and reverse rotation motor but just the block will be fine.
 

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If the seller says its a marine block, but the ad says a windsor? Find out what it is exactly because its either an M or a W, not both.

The M means 'modified' or 'marine'. Depends who you ask. Its a 351c style block/heads with a 351w crank. Its nothing more than a destroked 400. The 351m uses a 429/460 bolt pattern. The 351w uses a smallblock bolt pattern. Some call the 351m a big block 351. The bolt pattern is what they are referring to. It is also heavier than the 351w and has a taller deck height. The 351w uses a wet intake with coolant passages in the intake. The 351c uses a dry intake with no coolant passages in the intake. The M and C are similar. The C thermostat is flush against the block. The M thermostat sits about 3/4" higher.
 

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It is a 351w. He shouldnt be using 'marine' in the ad. Some people still find that confusing, even with pictures.
 

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Marine just means it was used in a boat, nothing to do with the 351M (modified) engine.
 

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PhD in Procrastinology
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Discussion Starter #8
It is a 351w. He shouldnt be using 'marine' in the ad. Some people still find that confusing, even with pictures.
I see you're taking a jab...nice
 

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PhD in Procrastinology
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Discussion Starter #9
Would I be wrong to offer him $100?
 

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Is a '72 block a "good one"?
All 351 are good ones. Fastback's" junk" uses a late model roller block.

The 69-71 ones are the stronger ones.

That one will still hold 700hp+ depending on your machinist. It's in the prep work and the balancing. If you fill it or not etc.

Sent from my galaxy s II
 

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If the seller says its a marine block, but the ad says a windsor? Find out what it is exactly because its either an M or a W, not both.

The M means 'modified' or 'marine'. Depends who you ask.
Just commenting as I have a casual interest with Ford engine history and I'm bored right now. Most 351 engines used for marine use were Windsors. They were referred to as "marine motors" as well, third parties had a relationship with Ford to make them and Ford made and sold some themselves. There was no difference in the actual block between marine and non marine though except for maybe the type of freeze plugs. The marine designation came from the other marine specific crap bolted on them. They were marine engines, not marine blocks.

The 351M wasn't nearly as popular for marine use. The Windsors of the time were higher revving and had cams for mid/high torque which made them a better choice compared to the 351M/400 motors.
What was the purpose of the 351M? It was first made in 74/75? The 351 Cleveland was done in 74 because there was no easy way to make it emissions friendly. The existing 400 was not as emissions friendly and there was a size gap to fill in for the soon to be outgoing FE 360 and 390 used in trucks. A complete switch over to a 351W was not possible because production, the fact it has a different bell housing from the FE and 400, and it was not specifically designed for heavy low rpm high torque things like the 400/351M or the FE was (larger bearings etc). Ford could have done a do over with a new design or put something together with existing stuff with some modifications. From that combination of events came the 351M. Emissions friendly (provisions for a thermactor) and the right size and durability for large cars and mid sized trucks. The 429/460 could still be used for the big stuff. The 351M was loaded up with emissions changes and lower and lower compression every year and became a turd. Its only good marine use at that point would have been as an anchor.

You are right, some people call the 351M a marine motor but I have no idea why. The design and the purpose of it had nothing to do with marine use. I guess because of the M.
Some people consider a marine motor a 351W that was dressed up for marine use. In my opinion, that is more correct but still really means nothing other than making your CL ad stand out.
 

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Yes^^ The 351 modified was very similar to a cleveland, but the front timing chain cover area had been 'modified' from it's cousin the cleveland. The water neck and thermostat areas were also changed a bunch.
 

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PhD in Procrastinology
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Discussion Starter #14
Thanks, guys. So if the only difference is the type of freeze plug, is this a good block to go after? I understand that you don't know about the actual integrity of the block.
 

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Thanks, guys. So if the only difference is the type of freeze plug, is this a good block to go after? I understand that you don't know about the actual integrity of the block.
As long as you are going to bore it and get better pistons, etc, the yeah thats a damn good block. Just post the casting number up from the block when you get it.
 

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just if it comes with a rotating assembly or dist.. trash it
 

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PhD in Procrastinology
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Discussion Starter #17
Called him, he won't sell the bare block. He wants $450 for the short block and $650 for the LB
 

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Moveon

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