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  #1  
Old 01-15-2008, 10:11 PM
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70Barracuda 70Barracuda is offline
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Default 340 to 400? answers needed

Guys,
So I have a good running 400 at a good price lined up. It's a 72 auto. I want to know if the crank is drilled for my 4 speed. What about a flywheel? Will my 130 tooth work? I don't think so. What about engine mounts?

Then if all that works out. I'm wondering about simple HP upgrades, like thinner head gaskets to up the comp. A decent cam. Just throwing the idea out there for any ideas.

My car is an original BB car, so theres where I'm coming from.

Thanks
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  #2  
Old 01-15-2008, 11:09 PM
68cuda92stealth 68cuda92stealth is offline
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Wanna sell your 340 to me if you put the 400 in?
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  #3  
Old 01-15-2008, 11:11 PM
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cageman cageman is offline
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yeah no crap, why would anyone put a 400 in place of a 340.
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  #4  
Old 01-16-2008, 12:20 AM
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70Barracuda 70Barracuda is offline
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Sure. Break out the cash!

My car is a big block car. It's all in the air for now.
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  #5  
Old 01-16-2008, 12:59 AM
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MOPEkid MOPEkid is offline
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Wait... autos and manuals need different crankshafts??!
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  #6  
Old 01-16-2008, 01:00 AM
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Is it an external balance 400, that will be info that is needed, and is the crank drilled?
Im not familiar with 400's, are they all external balance?
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  #7  
Old 01-16-2008, 01:06 AM
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I'll find out on Thursday. If not, it's over.
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  #8  
Old 01-16-2008, 01:14 AM
Paul Precht Paul Precht is offline
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The 400 is external balanced and the crank is not drilled for the pilot bearing if it came in a car with an automatic. The crank can be drilled by hand if you're good and the bushing custom fit, not hard to do either. The flywheel should be available new or used, Paul.
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  #9  
Old 01-16-2008, 02:13 AM
DartGT66 DartGT66 is offline
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Same flywheel in all cast crank BB's, so also a 440 or even a 383 cast crank flywheel works. A stock zero balance flywheel can also be drilled for the correct balance, but it's a pretty dedicated machine shop job. The crank doesn't have to be drilled for pilot bearing (I think they all are, just not reamed), there is currently "conversion pilot bearings" available that fits the torque converter centering ring in the crank. # 53009180, used stock in magnum engines with manual tansmissions. In stock form the 400 is not a very powerful engine. However, it does have a lot of potential and good parts availability with decent prices, especially popular to build a stroker out of one. Even as a 400 cubic incher it will be a good performer fi you raise the CR to decent level and use a performance cam. http://www.440source.com Just makes me wonder why no one is putting up a "440source" for small blocks?
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  #10  
Old 01-16-2008, 11:12 AM
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The engine allready has the thin gaskets as stock material. You'll need to mill the head or replace the pistons. KB makes slugs for this engine in Hyper-U's at zero deck. A little expensive by compare to the rest, but thats a low production engine by compare as well, so things of that nature go up in price.

The 400 has more potentail via cubes, 60 more or even better, stroked.
The engine is going to act much like the 340 it will replace. The strokes are close, 3.31 vs 3.38. But the bore size difference is hhhhuge!

Quote:
MOPEkid; Wait... autos and manuals need different crankshafts??!
Sometimes, yes. It is where the crank and the manual trannys input shaft meet, the crank needs to be drilled out to size and a bushing installed. If the crank is out of the engine, it is super easy.
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  #11  
Old 01-16-2008, 03:14 PM
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I think I'll just place a smaller cam in my 340. I'm tired of the high HP game.
I don't enjoy going to the drags much. It's hot and I stress anout something going wrong and possibly wreck the car at the track, how much money am I out. Alot!

Think I'll keep my eye out for a 383 runner to make my car closer to it's original self.

To that one dude, I'll sell the 378/340 if you got the cake..

Thanks
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  #12  
Old 01-16-2008, 10:29 PM
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Doing the flywheel swap is easy. Im pretty sure there are templates in the moparts archives for the rebalance. Can do with a drill.

in the pilot, use a roller pilot from a dakota. Then trim the nose of the inoput if you have to. It will be as good ore better than the factory hammer in piece of powdered brass.
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  #13  
Old 01-16-2008, 11:26 PM
68cuda92stealth 68cuda92stealth is offline
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Your in oregon? maybe if you were closer to the middle of the U.S.
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  #14  
Old 01-17-2008, 01:10 AM
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Good Go_, a small block in a factory big block car? And "why would anyone put a 400 in place of a 340..." well, when you can drop a 440 crank in it and get 110 more inches and about 200 more ft/lbs of torque. 440source conversion crank and some slugs. Itll look like the factory 383, rev like the 340 and itll rock. Sell the 340 and use the coin to make the 400 GO. That is my humble opinion.
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  #15  
Old 01-17-2008, 11:02 PM
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I like Pishta's thinking. Thats what I was thinking to do myself in my Magnum. The 400 by itself isn't to bad when equiped with some decent compresion and port work to breath, but stroking it! I'll argue it'll rev faster than a 340 with it's light bob weight.
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  #16  
Old 01-17-2008, 11:13 PM
Paul Precht Paul Precht is offline
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The bob weight is ok on the 400 but the crank is 76 lb, the 340 is about 55. In stock eliminator I use the cast 318 cranks in 340s, it's about 5 lb lighter, Paul.
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  #17  
Old 01-18-2008, 12:58 AM
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Quote:
Originally Posted by 68cuda92stealth View Post
Your in oregon? maybe if you were closer to the middle of the U.S.

Oh c'mon, thats what freight is for. 1970 340, O heads all Cometic, FBO engine. Demon to pan.

I might pick up the 400, the guy wants $400 for it. Says it runs good no smoke. Edelbrock intake too. See if I can work him on the price. Put it away for now. 440 crank, Eddie heads
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