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360 stroker help

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81j10honcho View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 81j10honcho Quote  Post ReplyReply Direct Link To This Post Topic: 360 stroker help
    Posted: Sep/20/2008 at 10:48pm
hey guys  well im stroking a 360 with a 401 crank since a 401 block is tough to come by and one thing im woundering is that has anyone done this and if so what kind of torque am i looking at with a summit 8600 cam 650 holly evenger carb performer intake  im gonna clean the chambers on the head free from any lips and rhoads lifters
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 1:39am
I am not clear on why you want to attempt to use the 401 crank in a 360 block with 401 blocks still around in ample supply plus the 401 crank has a longer stroke of 3.574 rather than the 360 stroke of 3.440 which will make your 360 pistons stick out above the top of the block by .055.  The pistons height of the 401 is 1.508 and the 360 pistons are 1.601 so unless you are also planning to have custom, shorter 360 pistons made to accomodate the longer stroke from the 401 crank you are much better off building up the 360 or looking some more for a 401 block due to custom pistons costing about $100 per slug which should cover the cost of a rebuildable 401 motor.
 
You can get more power than you can possibly use by simply building up the 360 so I am not sure why you would need the 401 crank even if it didn't push the stock pistons out of the block.  The 360 is a more rev happy engine than the 401 so unless you are looking for bragging rites with the bigger cubic inches, which no one will believe anyway because the block will still have the 360 markings on it, why bother putting up with all the aggravation of trying to stuff the 401 crank in the 360???
Dan Curtis, AZ AMC Collector Quality Restorations & Parts - amcmusclecars.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 10:57am
Alot of 360s will handle the 4.165 bore so you can use a stock piston. Mostly these types of combos are used when you have to utilize what you have and dont have a large budget. After weighing the options you may find that a 401 crank in a 401 block makes more power and in the end its up to you what you need out of this motor. A stroker 360 definately gets props :)
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 11:02am
I am of the understanding that only a very small number of 360 blocks have the thick web casting that can be bored out to 4.165 and that the vast majority of your run of the mill 360s can take a max of .060 overbore which is only 4.140 which will run pretty hot and is still .025 shy of 4.165 let alone 4.195 which is the standard .030 overbore of a 390/401.
Dan Curtis, AZ AMC Collector Quality Restorations & Parts - amcmusclecars.com
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Steve_P Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 12:54pm

there was a lot of discussion and info on this on previous forums, incl pics.  First off, the main bearing area web casting has nothing to do with the ability to bore the block- that's the ability to take a 4 bolt main cap.

IIRC, it was at least until the mid 70s that the 360 can go to std bore of a 401 as it used the same water jacket cores.  They also used the same water jacket cores with the 343 as the 390- this is how they ran a ~439 in the grant funny car with a 343 block.   Anyway, back on topic, IIRC, the 360s that could not go to a 401 bore had two extra core (freeze) plugs behind the bellhousing for easy ID.  Saying all that, a sonic check is always recommended and this is pretty standard equipment these days.
 
Finally, 401 blocks that aren't at least .030 over are NOT in ample supply.  Using the 360 makes perfect sense to me.


Edited by Steve_P - Sep/22/2008 at 12:54pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 5:27pm
You missed my point on the thick webbing blocks. It is my understanding that there is no question that the thick webbed block can be bored to a 4.165 size whereas, and as mentionoed in your repsonse, there are other 360s that cannot be bored.  Regardless and no matter what you do to it internally, you will still have a block with 360 markings on the side. 
 
Whether we agree or disagree that there are still an ample supply of 401 blocks around (I know of both a NOS 401 block and a used standard bore right here in the Phoenix area as I write this response) plus there are also 68/69 390 blocks, 70 390 blocks and 390 and 401 service blocks around that you can use the 401 crank and pistons without having to bore the motor to accomodate the 401 pistons to go with the 401 crank which can't use the 360 pistons. 
 
I agree that there are far more 360s blocks around but I'm also willing to bet that a large percentage of them are the ones with the later style water jacket casting that cannot accomodate being bored to 4.165.  Plus, most people and and even a higher percentage of the machine shops would not know the larger bore capable 360 block from the one that is able to be bored to 4.165.  So my point is why run the risk of having the wrong 360 block if you can find a 390 or 401 block and not have to worry about whether you have the correct or incorrect 360 block! 
 
On that subject, we currently have a used 390 service block in standard bore with 7/16ths head bolts holes and I have in my personal stash a NOS 390 service block that was decked .030 to accomodate the later model 401 pistons on stock 68/69 rods.  If anyone wants to build a clandestine motor that you can put in any 290 to 401 car without anyone being the wiser we have the blocks available. Wink.


Edited by amx39068 - Sep/22/2008 at 5:30pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 5:29pm
I havent seen a pre 78 360 block that couldnt take a 4.165 bore ;)
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Sep/22/2008 at 5:34pm
I would steer clear of Rhoads lifters if you are going to try and use the pump up lifter. They work well in the passenger side bank of the AMC V8 but the rear drivers side cant seem to stay pumped and IIRC the mopar oil slot was wrong for any kind of lift.
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcramblermarlin Quote  Post ReplyReply Direct Link To This Post Posted: Sep/24/2008 at 8:49pm
Agree and disagree; the discussion is still good to spit out all the nitty gritties of the issue! I have always been certain that the AMC 360 block casting does not have the same cast cylinder walls as the 401, and cannot be bored to accept the larger pistons because this is what all the AMC literature said, like their book "Performance American Style". There was a special "Trans-Am" block made in the early seventies for sure that does have thicker main webbing and cylinder walls that can be bored to the larger piston sizes, but I'm doubtful there is an ample supply of them out there. (uncertain how long AMC made the Trans-Am 360 block available) It seems the man who says that 360s will take the overbore has had some success with doing this. If so, this potential for bored out and/or stroked 360s is a newer discovery. He needs to assure the rest of us with some more specific info. (I seriously doubt that AMC would cast such fat cylinders for the standard 360s though because of cost and weight issues) Because AMC used higher quality nodular iron and carefully machined/snap in, very sturdy main bearing caps, I agree with "Performance American Style" that 4 bolt caps are not necessary, with exception of "Indy Cylinder Head" aluminum AMC V8 blocks; I have never heard of or experienced any weakness from the AMC V8 bottom end... in my opinion, this is a Chevy fix adapted to what is not a problem for AMC V8s. Something tells me that the man who wants to do the stroker 360 already knows he'll need new pistons. In my opinion, the 401 was never in ample supply, as a junkyard find or as stock equipment in an AMC product. But anyone with big money could  always buy one from somewhere... Many more 360s out there, and 304s; the "bread and butter" engines. In the "AMC Power Book" there is one article how to do a stroker 343 to 370 cid using a 390 or 401 crank and rods. They used custom forged pistons to compensate for the resulting change in piston pin height. The article concluded with an attitude of good success, as if the money was well spent. -Custom Pistons = how to 401 crank & rods in 360 block.                                                                                                                                                                                             The Chevy people have been doing the stroker thing for a while now; the 400 crank in the 350 block. What is not mainly expressed is that their 400 block has siamese cylinder walls; not good for shedding heat on performance built up engine. (the AMC 401 has full water jackets) Nevertheless, the Chevy people assert there is gain to be had from rod ratio geometry, citing the length of the rod has to do with how long the piston lingers at TDC. The idea is that a longer rod stalls the piston at TDC longer than a shorter rod, to take more advantage of valve timing. (On the other hand, there are those who argue that a shorter rod applies more leverage to the crank by it's geometry...) I've always been disturbed by the mainstream magazines who push for the stroker kits because I have read about piston temperature ranges -that they vary several hundred degrees from top to skirt, and this would affect the longevity of the piston pin -whether the oil there scalds or not. Whenever I rebuild and engine, I always notice scalded oil underside the piston top, inside the piston. Another complexity would be "piston slap" from the larger measure of piston pin height, saying that a numerically lower piston pin height affects less "piston slap", increasing the longevity of the bore from less rocking motion of the piston. I have not noticed any weakness in AMC engines due to piston slap, not even in the Rambler V8 that has over 1.6" of pin height; a good candidate for a stroker engine with it's long (6.+") forged steel rods and 3.25" short stroke crank.                                                                                                                                                                                                                                       Anyway, there is a more complex discussion to question how the rod ratio will affect the power output, of how the stroke will demand a different cam grind, of how the durability of the engine will be affected for good or bad. It is plausible in my mind that because of rod ratio and piston pin height the 401 crank and rods in the 360 block might have some undiscovered potential to be very torquey and durable. Shouldn't it weigh slightly less than a 401? The combo will yield approximately a 385 cid engine. It'll have good sized water jackets to shed heat. Not as much piston slap. The custom pistons should come out lighter from reduced pin height?... maybe this person is a Chevy spy merely posing the question to test the AMC guys, -to see if we know our block sides from a hole in the ground... and the other guy... to get our 360 blocks bored out too thin to try to eliminate some of the rompin stompin AMC drag cars out there! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote poormansMACHINE Quote  Post ReplyReply Direct Link To This Post Posted: Sep/24/2008 at 9:08pm
Originally posted by amcramblermarlin amcramblermarlin wrote:

It seems the man who says that 360s will take the overbore has had some success with doing this.  

Wouldn't simple sonic testing of the cylinders answer this this?
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