383, do you clearance the 350 block, machine the crank, or both?

[arlowf]

I hate to start a new thread when it seems that grumpy has exhaustively covered EVERYTHING when it comes to blocks and engine buildings already on this site, but this is sort of a specific question:
I have been following a step by step on prepping my block to become a 383 build, and I am confused on a point thanks to various people on facebook.

I thought you "clearanced" a 350 used block to fit a 400 crank to make a 383; but someone just told me the crank is supposed to be machined (cut) to fit the block. Which is it? Can I do one or the other, or do I need to do both? I can't just get away with cutting down the crank to fit a 400 in a 350 block can I?
is this one of those "it depends" questions?
To be more specific it's a 1 piece rear main seal 1986 used block, and I'm buying either an Eagle or Skip white 383 rotating assembly kit which includes a crank. Are those cranks already "made to fit" a 350 block, whereas a standard 400 crank isn't? Is that it?

EDIT: NEVERMIND GRUMPY
Sorry for asking this stupid question. Apparently you can buy different sizes of crank, the important thing is that it has 3.75 stroke. A lot of people use a 400 CID crank, which is bigger, and machine it down or clearance the block. But you can get a smaller diameter crank that is 3.75 and doesn't require machining that'll drop right in a 350 gen 1 block, right?
EDIT2:
Okay, apparently it's what I thought: It depends. Almost any aftermarket "383" crank you buy is going to be a 3.75 stroke that fits a 350 block, no machining necessary. A SCAT 9000 crank is a good example, though i'll probably get one of the cheaper Scat 9000 cranks, not the $1800 one.

 

[Grumpy]

generally you clearance grind the BLOCK using a crank and rod assembly designed to fit in a 350 block with either 5.7" or 6" long connecting rods that are DESIGNED to give max clearance to BOTH THE CAM LOBES AND BLOCK.
careful minimal clearance grinding is required but in many blocks its minimal,
I generally strongly suggest going with the more expensive forged steel 4340 cranks and use of SCAT rods, that are specifically designed to provide max clearance to the block and cam lobes, and forged pistons as that provides a much stronger rotating assembly less prone to having issues when properly balanced and clearanced.
grinding on the block if you selected the type of connecting rods and crank assembly DESIGNED to provide max rotating assembly clearances is not a huge undertaking, if you try to slap together random OEM parts that are modified to fit you'll need to do much more expansive clearance work and you could conceivably find the crank or rods won't clear the cam lobes, or in rare cases, if you get carried away, you'll grind into the block coolant passages,
this is never a cheap hobby, but its a whole lot more expensive if you have to buy replacement parts if you don,t do things correctly the first time and use the best parts you can afford, and understand your personal limitations, and exactly what you can expect from the choices you make, obviously you'll need to verify piston to bore clearances, ring end gaps, bearing clearances, connecting rod to cam clearances, rod to piston skirt clearances, dial in the cam, check the rotating assembly to windage tray, clearance, install an oil pump and pick-up etc.

Pneumatic 1/4 in. Die Grinder with 3 In Extension

Amazing deals on this 1/4In Air Die Grinder With 3In Extension at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

HF sells a decent cheap/disposable air die grinder

https://www.henryschein.com/us-en/dental/c/burs-diamonds/carbide-burs?gad=1&gclid=Cj0KCQjw2qKmBhCfARIsAFy8buJUCFsVwPOcY8T3REQ7qCrB2UJoTT8SxDYqv-exYvKJIyhdKRScDswaAhnpEALw_wcB

I learned that long ago,
“Quality is like buying oats. If you want nice, clean, fresh oats, you must pay a fair price.
However, if you can be satisfied with oats that have already been through the horse ...
that comes a little cheaper.”

thats why I generally suggest SCAT rotating assemblies
and having the required precision measuring tools, if you save $400 on the rotating assembly initially,
but need to spend $250 to get it balanced and $250 to get it polished ETC, what have you gained,
especially if its lower quality cast iron vs cast steel in a SCAT crank
remember in most case you still need a flex plate/flywheel and damper and associated bolts/fasteners etc.

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[Grumpy]

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[arlowf]

Thanks grumpy.

Yeah it's the rods I have to clearance for not the crank; I get it.
expensive forged steel 4340 cranks and use of SCAT rods
That's what I've been looking for all day in an internally balanced kit with for 1 puevectear main seal with (and this is the hard part) Hypereutectic pistons. I don't want forged or steel pistons; just forged crank and rods.
Hard to find that combo.

 

[Grumpy]

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[arlowf]

Grumpy I found the kit I'm looking for that has all the things I like, but is confusingly called an unbalanced assembly... with an internally balanced crank. Makes no sense.

So yeah I'm calling Scat. SkipWhite offers assemblies with scat cranks and they claim to balance all their kits but they don't offer the internally balanced cranks. Plus SkipWhite's people treat me like trash when I call them because I'm just spending 4k with them, not 10. Don't have time for my questions about their kits, essentially.

 

[Grumpy]

SkipWhite...
does not have an enviable reputation for standing behind his product quality ,
from what I've heard over the years from his former customers

I generally deal through summit, or jegs or I try hard to deal direct with the part manufacturers like,
erson, lunati, TRICK FLOW, J&E, BRODIX, CLEVITE, AFR, DART, KINSLER, CROWER, HOLLEY, WEBER, HAYS, SCAT,
when I can do so.

do the required research and find a local machine shop you can trust to do work correctly
, and hopefully at a decent price and one that delivers parts.
when they quote you at the price and date they quote you.
if you can do much of the work and have the skills and tools that's ideal,
but it helps if the local machinist, is knowledgeable skilled and sympathetic to your project goals,
YEAH its going to cost you a good deal more
but its better if its correctly done, the first time,
if your not that skilled or equipped/ knowledgeable!
if the local machinist, can advise and if required guide or even partly complete the project,
if thats something your not equipped to do personally
remember, being out a couple hundred dollars more than you expected ,
is far preferable to having a rod punch holes in a head or block, because you screwed up,
on some clearance or bought the wrong parts

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http://garage.grumpysperformance.com/index.php?threads/think-thru-your-goals.10606/#post-73288

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[NewbVetteGuy]

Arlow, you did well to post these questions to this forum. I'm on that very confused / confusing FB group and saw your posts there.

IMHO, a forum, is a way better place to work through some of these questions / issues.


Adam

 

[arlowf]

Adam,
I get it, but I get a TON of differing opinions on facebook. You're right though that I need to take what I learn from there, consolidate it here, and ask very specific questions instead of "google" questions here. I'm sorry for wasting Grumpy's time with some of my other questions, I didn't know how simple they were until I had already asked them. I've made a build thread here and I'm answering as many questions as I'm asking.

 

[Grumpy]