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Old 03-11-2010, 10:21 PM
party340 party340 is offline
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Default 440 overbore?

How far can a 1976 440 rv block bored? Dad wants to put one in his 1999 dakota. Has anyone here done this?
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Old 03-11-2010, 10:48 PM
John Van John Van is offline
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I have a '72 block bored over .055 . Bring your block to a machine shop,have them sonic test the cylinder walls to see how much they can be safely over bored if needed. Good luck!
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Old 03-11-2010, 10:53 PM
Green66 Green66 is offline
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Default Over bore

The old school of thought was that the later blocks were Thinwall castings, but there has been a lot of research done sonic testing various blocks that debunks this. There is an article on the 440source website that is very informative I can not post links yet but just look under the heading "Everything you wanted to know about blocks and more".

So I see no reason if the block is Ok that you could not go .060 if you absolutely had to.
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Old 03-11-2010, 11:23 PM
440+6 440+6 is offline
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my buddy just built a 500 horse 440 from a '78 block taken .040 over.....no problems
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Old 03-11-2010, 11:25 PM
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bulldog426 bulldog426 is offline
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i've actually heard the later blocks are made a little stronger, and can actually handle a little more boring, 340 what part of la you from??
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Old 03-12-2010, 12:56 AM
dave5711 dave5711 is offline
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There is some good info on the AR engineering site, where Andy weighed bare blocks to see what mass of iron they had. As mentioned the later blocks weren't worse. If anything they were better. Info on 440 source backs this up as well.

Depending on what services your local machine shop offers, you may not be able to get sonic checking done.

Personally, I would not be afraid to bore any big block .030 over without a sonic check, as long as you were doing a reasonable street strip build (under 600 hp)

There are a lot of things that are more likely to go bad than the block itself.02
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Old 03-12-2010, 03:53 AM
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ehostler ehostler is offline
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As Josh stated, a sonic test will determine your max over bore. I've seen 440s that made it to 60 over with no problems. I've seen others become scrap metal at 40 over. A sonic test will remove all guess work.
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Old 03-12-2010, 04:43 AM
cudabob496 cudabob496 is offline
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I bored my 496 to 40 over. Was told not to go to 60 over.
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Old 03-12-2010, 04:46 AM
cudabob496 cudabob496 is offline
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Good info below regarding ring seal!! (Probably why I was told to only go 40 over)

Mopar Action Tech Question
Gary Angell, Mason City, IA , 1968 Dodge Dart 446

How much can I bore a 1972 casting 413
It is a HD block with cast-in water pump bosses in the rear of the block and extra heavy braces on the sides.
Can it be bored out to 440 spec. safley?

Unlikely. But, really, the only sure way to answer this is via a sonic wall thickness check. You'd like at least 0.090" (major thrust side) at your final bore size. But remember the axiom: thick cylinder walls make for a good ring seal. And a good ring seal makes power - and durability. I'll take beefy cylinder walls over another 10 C.I.D. any day of the week!

Rick
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Old 03-12-2010, 08:42 PM
party340 party340 is offline
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Thanks for the replyes. He was thinking that the later blocks could only take a 0.020 overbore. So it seams that 0.030 would be fine.
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Old 03-12-2010, 11:24 PM
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bulldog426 bulldog426 is offline
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usually the rv engines you will find aren't very high mileage anyway, because it was right before that big gas crunch, and most people parked em in a shed and forgot about em, my 78 casting 440 only had 19,000 miles on the odometer, "i was thinking that's probably 119,00, or 219,000" but when i pulled the engine down, you could still see the factory hone marks in the cylinders the main and rod bearings could have been reused if i really wanted to, my machinist said it was the best engine he had ever seen, a pity it was a low compression motor and i had to buy pistons for it, otherwise i would've left it as is.. i notice you are from la, if you aren't to far from ms gulf coast region, i can reccommend a dang good machinist this man knows more stuff about engines than hughe hefner has silicone, and he was taught by one of the best
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