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ok, so here's my dilemma. i recently got a good deal on a 383 shortblock($250 and the 350 block has already been machined, new bearings, 400 crank and pistons/rods etc). the reason it was so cheap? the guy somehow thought he could get away with using regular 350 pistons on 5.7 rods. and of course they come slightly above deck height. so i was just going to buy new stroker correct pistons. thing is, the pistons in there now are brand new speed pro aluminum -5cc flat tops and i'm on a tight budget. i heard that you can use stock 400 rods in a stroker and still use regular 350 pistons. i can get a set of balanced re-worked/re-sized 5.565 rods for $50 as apposed to spending $300 on new pistons/rings. i'm not trying to cheap out, but every penny counts. odds are, i'm only going to be using this motor for this summer and build my dream motor over the course of next winter. so i don't want to put too much into it. anybody ever use 5.565 400 style rods in a stroker? what problems might occour. will they need to be cam clearanced? my cam/head setup should peak between 5,500 and 6,000 rpm so i won't be reving it any higher than that. any dangers in using the 5.565 rods?
 

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Discussion Starter #3
yeah, i planned on having everything re-balanced once i figure out the rod/piston situation. i bought it without a flexplate and the crank is external balance so i figured that would have to be done no matter what. thanks for getting my back though!
 

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The short answer is "yes", but don't ask me how. My 383 was originally built about 17 years ago, so I don't recall the details and probably wouldn't have understood them at the time. But, when I pulled the motor apart a few months ago for a rebuild I was reminded that I was using 400 rods. I think the early way of building a 383 was to use these shorter rods so that stock 350 pistons could be used and so that you wouldn't have to clearance the block at the pan rail. I do recall some filing of the pistons to clear the crank, but I don't know about cam clearance. My 400 rods don't appear to be ground on so I don't think there was any issue clearing the cam. Based on how hard I ran my motor for many years I wouldn't be afraid to use the 400 rods in a mild street 383 motor. It may not be the ideal way to build one considering what is available today, but it can be done.
 

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I could be wrong but I bet they will still be sticking out of the block even with the shorter rod....the difference in stroke between the 400 crank and the 350 crank is .270" EXTRA stroke

the difference between the 5.7 350 rod and the 5.565 400 rod is only.135" LESS rod length center to center...so to me...like I said I might be wrong but I think the piston would still stick out of the block by about .135". you need to get pistons with the proper CR height (PIN HEIGHT) to match the rod and stroke combo you plan on using....Good luck...:)
 

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bowtie0069 said:
There have been about a bazillion 383's built with stock rods; no reason you couldn't do it too.
I agree but I bet they have a different CR height(pin height) on the piston then the stock 350 piston CR height(pin height):)
 

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I think what you wanna do is:

1) buy pistons with the right pin height for the 5.7 rods
2) get the resulting assembly balanced
3) sell the original (incorrect pin height) pistons on eBay

The new pistons don't have to cost an arm and a leg, especially if you're going to be reasonably nice to it anyway (no nitrous) Lots of choices here, as this is a common combo. Measure the bore to check what oversize you need (should be .030 if it's really a 383...) You really *should* have the pistons before the bores are done so they can be honed for proper clearance, but...you will probably be OK off the shelf. You will want to check that when you have the new pistons...or have the machine shop check for you and re-hone as needed.

As was mentioned above, make sure you pick pistons that will work with the heads to create an appropriate compression ratio.
 

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.135 X 2= .270

:eek: .270 stroke is .135 below the C/L of the crankshaft and .135 below the C/L of the crankshaft.:D

Made this mistake B4 myself :eek:
 

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RED67 said:
:eek: .270 stroke is .135 below the C/L of the crankshaft and .135 below the C/L of the crankshaft.:D

Made this mistake B4 myself :eek:
ahhh...ok...my mistake:eek:

So the piston would only be .135" higher at TDC...not .270" higher?

So then the rod should work I guess as there is a .135" differenece in rod length

Another question...do 350 pistons and 400 pistons have the same pin height?
 

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Discussion Starter #11
o.k. so does that mean i can get away with the 5.565 rods? i' may have to change out the pistons anyways(see my bore size post) but this bottom end is only going to be used for a summer before i build my "dream" motor from scratch next winter. so i'm trying to keep on as tight of a budget as possible. if i can get away with just spending the $50 for the rods, that would be great. so the 5.565 rods are possible? if there is a slight height problem, don't they make a head gasket that is used for shimming purposes? i dunno, just trying to keep costs as low as possible. i hate to spend a bunch of money on a bottom end thats gonna get re-done soon enough anyways. thanks for all your input on this. you guys are the best! by the way, i almost had a heart attack whe the site was downthe other day! made me realize just how valuable everyone here is!!!
 

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[QUOTE='74hatchback]o.k. so does that mean i can get away with the 5.565 rods? i' may have to change out the pistons anyways(see my bore size post) but this bottom end is only going to be used for a summer before i build my "dream" motor from scratch next winter. so i'm trying to keep on as tight of a budget as possible. if i can get away with just spending the $50 for the rods, that would be great. so the 5.565 rods are possible? if there is a slight height problem, don't they make a head gasket that is used for shimming purposes? i dunno, just trying to keep costs as low as possible. i hate to spend a bunch of money on a bottom end thats gonna get re-done soon enough anyways. thanks for all your input on this. you guys are the best! by the way, i almost had a heart attack whe the site was downthe other day! made me realize just how valuable everyone here is!!![/QUOTE]

The 5.565" rods will work just fine as long as they clear the piston skirt. Some 350 pistons have a long shirt that might interfere with the rod.
 

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Discussion Starter #13
thanks for everybody's help! sorry that my post on bore size and this one kinda got overlapped. i think i'm gonna try to get away with the 400 rods, as long as my bore size is usable(but thts what my other post is for). man, i don't know what i would do without you guys. (probably finally take some kind of automotive class):D :eek:
 

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This is the original way to build a 383

Cut down mains on 400 crank
use the 5.56 rods on 350 pistons. good to go.

Im contemplating this also seeing I have everything but the pistons
 

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nah I got a 350 block here also. The shop I had clean and mag said the bores are perfect as stock but I wouldnt go farther than .030 if I dont have to
 

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Discussion Starter #17
honestly, i didn't really think you would want them. they aren't exactly first choice pistons. only reason i might use them is because i don't want to put expensive pistons in a block thats gonna get re-done after the summer anyways. this summer is all about getting the car on the road as cheaply as possible (with as much horsepower as possible of course). if i totally fry it out by the end of summer, no big deal and no expensive parts/labor wasted.
 
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