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290 pistons

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poormansMACHINE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote poormansMACHINE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2011 at 11:17pm
290 through 401 have the same bore spacing so if it's lacking then they're all lacking.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Buzzman72 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2011 at 11:19pm
SHHHHHHHHHH!
 
Some Chevy guy probably told him that...so it's just GOTTA be gospel!  Toilet
Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 17tamx Quote  Post ReplyReply Direct Link To This Post Posted: Oct/01/2011 at 11:30pm
Isn't the bore spacing the same between a 290 and a 401?
Bore spacing is based on the dimensional limitations of the basic engine block design. The AMC thinwall casting Gen II and Gen III V8's originally designed by Dave Potter are neither small block or big block but really a medium block. The external dimensions are the same for all the engines. The internal dimensions of the castings where changed as both bore and stroke increased to give larger displacement numbers.
 
Don't we have 4.40" Bore spacing on our AMC Gen II & Gen III V8's?
 
I hear about guys running 4.225" (4.165 plus .060) on their 390 and 401's all the time.
 
Is anyone running a larger bore than 4.225" at this time?
 


Edited by 17tamx - Oct/01/2011 at 11:36pm
Kirk P. Fletcher
70 AMX BBG w/Shadow 390 4sp
71 SC360 Wild Plum Ram Air 4sp
67 Rogue Convert 343 4sp
66 Rogue Hardtop 290 Auto
66 440 Convert 232 Auto
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wantajav View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 7:31am
bore spacing = distance from bore center to bore center, not the diameter of the bore itself
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wantajav View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 7:34am
4.75" the same as a Buick 400-455
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonb79 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 8:53am
Correct me if I'm wrong but isn't the bore on a 290 3.75 and the stroke 3.28.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 9:05am
four 3.75" holes that are located 4.75" apart in the engine block.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigbad69 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 9:22am
Originally posted by jonb79 jonb79 wrote:

...  I was under the impression a 290 could perform out like a ford or chevy 302 or even a chrysler 318 with some mods...
If you're talking Boss 302 or Chevy 302, those were purpose built engines for racing. They were put in a limited number of production cars in order to be able to use them for Trans-Am. At the time, AMC was using the 290 or 304 and they were competitive.  None of these engines were known as great street performers because they made their power at high RPM.

Nowhere in this thread have you mentioned the purpose of the car. Is it street, street/strip, or race only? That makes a big difference on the engine you build. Street performers really need low end grunt because you can't achieve high RPM for very long. For street/strip you want a wide power band to take advantage of higher RPMs but still have low end for the street. For race only, you have to decide what class you want to be in, then build the engine (and car) specifically for that class.

A guy I know has a 318 in his Dart (street only). It has 340 heads, an upgraded cam, intake, and carb. He says it runs like a 340 and he's right. But that's a lot of work to get it to the level of a stock 340. If he started with a 340 or 360 and did the same work, he would be in the range you are looking for.

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poormansMACHINE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote poormansMACHINE Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 9:40am
Are you sure you're ready to build an engine?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonb79 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/02/2011 at 4:05pm
Im going to build something for the street and once inawhile at the strip. Most likely going to buy a 360. love that chevy guy comment.
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