Re: 383vs400 crankshaft
[Re: Performance Only]
#1410723
03/31/13 08:36 PM
03/31/13 08:36 PM
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Joined: May 2003
Posts: 6,569 Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
Posts: 6,569
Downtown Roebuck Ont
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John, 71 was the last year for the 383 and as you know, 72 was the first year for the 400. It stands to reason they wanted to deplete the old 383 cranks. I think we all know they'll physically interchange dimensionally. That does not mean that the component weights were the same. At the factory all they had to do was drill the counterweights differently.
I understand that but the crankshaft was individually balanced to a set bobweight, if the 400 bobweight was that much different than the 383 they would have given the crank a different part number and a different balance but they didn't...so a parts room 2268114 crank would have been supplied as a direct replacement for either the 383 or the 400.
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The pistons are not close enough in weight to just swap cranks from a 383 to a 400 and not rebalance it.
Again, depends on how much imbalance is considered "too much"....evidently the factory thought it wasn't enough to warrant a different part number.
A crankshaft bought over the counter did not have balance holes drilled in it. Aside from that, how many forged crank 400's were ever built? I've never seen one.
If you have ever seen a 400 that had a manual trans behind it, it had a forged crank in it. Lots of trucks for sure.
Kevin
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Re: 383vs400 crankshaft
[Re: pushbutton]
#1410726
03/31/13 09:46 PM
03/31/13 09:46 PM
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Joined: Jan 2003
Posts: 10,019 Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,019
Frostbitefalls MN (Rocky&Bullw...
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Can you bore a 400 block large enough to take a .030" over 440 piston?
That would only be .008 overbore. A .060 440 piston would be .038 over bored 400. 400 bore, 4.342. 440 bore, 4.320 a Motor home or low compression passenger car piston might work. Even if you find the right piston in the bone pile, it may be way off on balance specs. According to the weights listed for replacement pistons, the stock 440 pistons are possibly 75 grams heavy. That equals a cut of about .110. Too much. Best bet is a stock weight replacement piston, or run what you have.
Last edited by gregsdart; 03/31/13 10:20 PM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 383vs400 crankshaft
[Re: Pale_Roader]
#1410727
03/31/13 11:48 PM
03/31/13 11:48 PM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
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You could spend yourself poor at the machinist to reinvent the whole thing, or you could spend a few hundred on pistons. I've driven myself bats with the math on this puzzle... just buy the damn pistons!
That said... i have a No-buck zero-deck 400 ready for the rebuild in my shop. Found a standard bore re-cond. 400 at the junkyard, free in trade. Had some .030" over 440 pistons (stock low comp, perfect comp ht. for lowdeck) kicking around. Enough rods to build a V700, and a couple steel 383 cranks. Bore the 400 to just 4.35", flycut the pistons, balance it all and pow! Zero-deck/steel crank/balanced 400 to go with some nice 516 heads and .040" quench. Total cost? $125 + machining/balancing. Kinda hokey... but i bet it screams.
All that and not one use of your sillyass ov ... ..
Did you add valve notches to those pistons? If you didn't don't get crazy with your cam choice.
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Re: 383vs400 crankshaft
[Re: JohnRR]
#1410729
04/02/13 07:30 AM
04/02/13 07:30 AM
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Joined: Jan 2005
Posts: 4,862 the frozen wastes...
Pale_Roader
Swears too much
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Swears too much
Joined: Jan 2005
Posts: 4,862
the frozen wastes...
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Quote:
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You could spend yourself poor at the machinist to reinvent the whole thing, or you could spend a few hundred on pistons. I've driven myself bats with the math on this puzzle... just buy the damn pistons!
That said... i have a No-buck zero-deck 400 ready for the rebuild in my shop. Found a standard bore re-cond. 400 at the junkyard, free in trade. Had some .030" over 440 pistons (stock low comp, perfect comp ht. for lowdeck) kicking around. Enough rods to build a V700, and a couple steel 383 cranks. Bore the 400 to just 4.35", flycut the pistons, balance it all and pow! Zero-deck/steel crank/balanced 400 to go with some nice 516 heads and .040" quench. Total cost? $125 + machining/balancing. Kinda hokey... but i bet it screams.
All that and not one use of your sillyass ov ... ..
Did you add valve notches to those pistons? If you didn't don't get crazy with your cam choice.
DAMMIT!!!!!
I'll try harder next time. I WILL, i promise!
Flycut pistons (for valve clearance). Yes, part ov the budget (see?? see???). And that actually was the hangup that back-burnered the whole deal for now... flycutting the pistons. I'm too lazy to get that neat Isky tool and do it myself, and my machinist was too far away for the back and forth needed to get it going. No way i'd put together a neat combo like this and limit myself on cam size.
I wish there was a standard template for flycutting a piston for valve notches. Something that didn't require giving him the entire pile or assembling it to figure it out. Or maybe i'm overthinking things?
The whole point with this combo was NOT to succumb to the 'might-as-wells'...
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Re: 383vs400 crankshaft
[Re: Pale_Roader]
#1410731
04/02/13 12:37 PM
04/02/13 12:37 PM
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Joined: Jan 2003
Posts: 75,094 A Banana Republic near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,094
A Banana Republic near you.
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Quote:
Quote:
Quote:
You could spend yourself poor at the machinist to reinvent the whole thing, or you could spend a few hundred on pistons. I've driven myself bats with the math on this puzzle... just buy the damn pistons!
That said... i have a No-buck zero-deck 400 ready for the rebuild in my shop. Found a standard bore re-cond. 400 at the junkyard, free in trade. Had some .030" over 440 pistons (stock low comp, perfect comp ht. for lowdeck) kicking around. Enough rods to build a V700, and a couple steel 383 cranks. Bore the 400 to just 4.35", flycut the pistons, balance it all and pow! Zero-deck/steel crank/balanced 400 to go with some nice 516 heads and .040" quench. Total cost? $125 + machining/balancing. Kinda hokey... but i bet it screams.
All that and not one use of your sillyass ov ... ..
Did you add valve notches to those pistons? If you didn't don't get crazy with your cam choice.
DAMMIT!!!!!
I'll try harder next time. I WILL, i promise!
Flycut pistons (for valve clearance). Yes, part ov the budget (see?? see???). And that actually was the hangup that back-burnered the whole deal for now... flycutting the pistons. I'm too lazy to get that neat Isky tool and do it myself, and my machinist was too far away for the back and forth needed to get it going. No way i'd put together a neat combo like this and limit myself on cam size.
I wish there was a standard template for flycutting a piston for valve notches. Something that didn't require giving him the entire pile or assembling it to figure it out. Or maybe i'm overthinking things?
The whole point with this combo was NOT to succumb to the 'might-as-wells'...
ov
When you said flycut I thought that was to trim the top of it to get it to zero , my bad.
You could have bought some small carbides and soldered them to valves and cut them that way , keeping with your bucks down theme
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Re: 383vs400 crankshaft
[Re: Performance Only]
#1410737
04/02/13 06:52 PM
04/02/13 06:52 PM
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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
master
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master
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
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"I don't understand how both cranks can be the same part number since they both have a different stroke from the other. Can you post a copy of the parts information your talking about? A 383 is 3.375 stroke and a 400 is 3.380 stroke. Granted it's only .005" different but i don't believe they used the same part number crank for both engines. I will however believe it when you prove it to me." I don't think you're correct about this. I have always understood that All B cranks share the same stroke and that this stroke is ACTUALLY 3.375, but many application data sheets round up to 3.38"
Last edited by StealthWedge67; 04/02/13 06:55 PM.
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: 383vs400 crankshaft
[Re: StealthWedge67]
#1410738
04/03/13 11:06 AM
04/03/13 11:06 AM
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Joined: Jul 2010
Posts: 2,091 Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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The factory service information lists the stroke i mentioned, as does Chiltons and motors manuals. Some people do round the numbers up but that doesn't make it accurate.
Last edited by Performance Only; 04/03/13 11:34 AM.
machine shop owner and engine builder
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Re: 383vs400 crankshaft
[Re: Performance Only]
#1410740
04/03/13 03:04 PM
04/03/13 03:04 PM
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Joined: Jan 2003
Posts: 25,988 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,988
Rio Linda, CA
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My Motor's Manual shows the 400 stroke as 3.375" Every FSM shows the 400 stroke as 3.375".....3.38" is just 3.375" rounded off to two digits. The 383 and the 400 have the same stroke and the forged cranks have the same part number easily verifiable in any factory parts book.
The INTERNET, the MISinformation superhighway
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Re: 383vs400 crankshaft
[Re: John_Kunkel]
#1410741
04/03/13 04:22 PM
04/03/13 04:22 PM
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Joined: Jul 2010
Posts: 2,091 Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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My 1970 FSM shows the 383 as 3.375 In the end it doesn't really matter. One would be foolish to replace one crank with the other and not balance it. The factory balance was not that close to begin with and the 383 and 400 DO have a different bobweight, believe it or not.
machine shop owner and engine builder
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