Re: 400 motor
[Re: DusterKid]
#177150
12/28/08 06:09 PM
12/28/08 06:09 PM
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Joined: Nov 2004
Posts: 3,544
Syracuse,NY
CompWedgeEngines
master
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master
Joined: Nov 2004
Posts: 3,544
Syracuse,NY
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OK, I'm going to try and help you out here without making this too long. You have said a lot, but its not all correct!
The stroke of a 400 low deck motor is 3.38" and a RB ( 440) is 3.750. The deck heights are 9.98 vs 10.725 respectively.
A typical 440 piston is 2.061 inches. Take that, add it to the stock 400 stroke, add for crank travel and add in the stock 440 rod length and you'd arrive at 10.511 inches. That means the piston would be above the block over .500 inches.
Take your scenario and use the 400 rod ( 6.358, add for crank throw, and add in the height of a stock 440 piston and you would arrive at 10.109, which means the piston is still .11o above the deck surface.
What you are ultimately asking for is a 451" or 470" type of stroker motor, very very common.This would be a 440 crank in a 400 block, with changes made to the crank, piston and rods. The pistons need to be custom ( there are some stocking part numbers now however) because of the difference in compression height.
Adding stroke will have more of an impact on compression that will the larger bore. The larger bore helps in other areas however.
The stroker motor will certainly run better if cammed properly and especially in a heavy car. The addition of the cubic inches alone doesnt amount to a hill of beans. Its the additional stroke that creates the torque, which moves the vehicle. There are many other factors, but this is a quick explanation.
RIP Monte Smith
Your work is a reflection of yourself, autograph it with quality.
WD for Diamond Pistons,Sidewinder cylinder heads, Wiseco, K1 rods and cranks,BAM lifters, Morel lifters, Molnar Technologies, Harland Sharp, Pro Gear, Cometic, King Engine Bearings and many others.
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Re: 400 motor
[Re: CompWedgeEngines]
#177151
12/28/08 06:25 PM
12/28/08 06:25 PM
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Joined: Nov 2003
Posts: 4,027
Dearborn Hts, MI
Sledge_57
master
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master
Joined: Nov 2003
Posts: 4,027
Dearborn Hts, MI
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Sounds to me what he's looking to do is increase the compression without breaking the bank. Doesn't someone, KB maybe, make a higher compression piston for a 400? Of course if you got the money a stroker is the way to go with that 400, a 470 is lots of fun, trust me 
Doug
1967 "Pedal Car" 500" low deck , TF 727, 4.30 Locker
Best to Date: 11.67 @ 114.9 1.64 60ft
"Kids in cars cause accidents. Accidents in cars cause kids..."
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Re: 400 motor
[Re: Sledge_57]
#177152
12/28/08 06:27 PM
12/28/08 06:27 PM
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Joined: Feb 2003
Posts: 1,572
wisconSIN
Blown61
pro stock
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pro stock
Joined: Feb 2003
Posts: 1,572
wisconSIN
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Quote:
Sounds to me what he's looking to do is increase the compression without breaking the bank.
Doesn't someone, KB maybe, make a higher compression piston for a 400?
Of course if you got the money a stroker is the way to go with that 400, a 470 is lots of fun, trust me
How does one make a 470??
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Re: 400 motor
[Re: Blown61]
#177155
12/28/08 07:21 PM
12/28/08 07:21 PM
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Joined: Nov 2003
Posts: 4,027
Dearborn Hts, MI
Sledge_57
master
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master
Joined: Nov 2003
Posts: 4,027
Dearborn Hts, MI
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Quote:
Quote:
Sounds to me what he's looking to do is increase the compression without breaking the bank.
Doesn't someone, KB maybe, make a higher compression piston for a 400?
Of course if you got the money a stroker is the way to go with that 400, a 470 is lots of fun, trust me
How does one make a 470??
Some answers here:
http://www.moparts.org/Tech/Archive/bb/38.html
Doug
1967 "Pedal Car" 500" low deck , TF 727, 4.30 Locker
Best to Date: 11.67 @ 114.9 1.64 60ft
"Kids in cars cause accidents. Accidents in cars cause kids..."
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Re: 400 motor
[Re: DusterKid]
#177156
12/28/08 07:23 PM
12/28/08 07:23 PM
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Joined: Mar 2005
Posts: 303
southwest Alabama
challenger73400
enthusiast
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enthusiast
Joined: Mar 2005
Posts: 303
southwest Alabama
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Quote:
Thanks for the info guys. Reason I asked is I have a 400 block that was bored .010 over and has .030 440 pistons in it and they come flush to the top of the block. Not sure what part # the pistons are but remember that they were purchased and once received noticed that they were designed to lower the compression in the motor to be capable of running "todays gas". So I'm guessing they are .030 replacement pistons for the newer 440 motors (76-78) that only had 8:1 compression or so. I can't remember what rods were used in the combo and I don't want to tear the motor apart as it is complete, so I'm thinking I must have used the 400 rods and with the 440 pistons being (I don't know the correct term, but have the wrist pin higher up in the piston to lower compression) made it come flush to the top of the block.
That's what I did. My pistons ended up .008 in the hole for a 9.3:1 CR. Stock 400 rods but I don't remember the part no for the pistons. I went with a .038 over bore and .060 over 440 pistons.
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Re: 400 motor
[Re: DusterKid]
#177157
12/28/08 08:21 PM
12/28/08 08:21 PM
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Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,923
NC
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Quote:
Would taking a 400 motor, and having it bored out .010 and use a 440 .030 piston help bring up the compression?
I see you are asking about using a 400 crank and 440 pistons in a 400 block. There were several variations, by year, in 440 piston compression heights (pin to top of piston). Even some replacement pistons had variations from factory specs.
I have no idea what you have. But for example, I measured:
440 piston: 1.924" CH
400 piston: 1.826" CH
The block height can also easily vary 0.030" from the factory.
Here is an example, put in your numbers:
1.69 Stroke divided by 2 (3.38/2)
6.358 Rod length
1.926 Piston Compression height
------
9.974"
If the block was 9.980", the piston would be 0.006" down the hole.
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Re: 400 motor
[Re: Blown61]
#177160
12/30/08 04:24 PM
12/30/08 04:24 PM
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Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,923
NC
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Quote:
Is this doable with a 383 and a standard bore 440 piston?
The 383 bore is 4.25", while the 440 bore is 4.32". Too much to bore, the cylinder walls would likely be too thin, IMO.
The 400 bore is 4.34" to start with.
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Re: 400 motor
[Re: 440Jim]
#177161
12/30/08 07:00 PM
12/30/08 07:00 PM
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Joined: Sep 2003
Posts: 1,397
Toronto Ontario, Can
Glen440
pro stock
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pro stock
Joined: Sep 2003
Posts: 1,397
Toronto Ontario, Can
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I looked into the 440 piston in a 400 a long time ago. The biggest drawback is those cheap pistons have no valve reliefs. It was cheaper for me to just put cheap KB's in it.
87 dakota 6.1 hemi
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