383 scat or eagle??
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Instructor
Joined: Dec 2007
Posts: 246
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From: colonia New jeresy
383 scat or eagle??
I asked for some tech info on building a 400 hp 350.my parts will need machine work cut crank/new rod bolts resize/new pistons. so 4 about the same price i can build a 383.scat or eagle that is the question do i buy a kit and give it to the machine shop and check the crank/rods for quality machine work?[ i want to build the motor ].can i trust the machine work as far as rod/main bearings true/the same size/clearance? i herd bad thinks about both .the quality control is hit or miss if its bad then do i let my machine shop fix the parts rebalance cut and grind Or should i use my 350 parts and build that i know the parts are gm steel crank/ pink rods they need to be machined for a rebuild?what do u think?
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From: Corsicana, Tx
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You can never assume bearing clearances will be right. The bore size of the mains for example may be within tolerances..but with a tlerance stack up between the bores, the crank and the bearings it could be anywhere.
If you're buying a crank anyway. no reason to not go 383 or 396 these days.
If block is being done at shop anyway to bore etc...then they can ck clearances for you and then you can assemble it all. Sometimes best to let them get parts unless they are OK with you getting them. Most shops have preferences.
You might also look at Mahle...they have some nice kits. Between SCAT or Eagle...I'd go SCAT for better machine quality out of the box. Get an internal balanced assy...makes things lots easier. Sometimes best to buy unbalanced assy and let local shop actually do it. Quality is better if it's a good shop.
If 400HP is all you're after..the 350 will get you there with good heads and cam. Stroker just adds some more and makes it easier.
JIM
If you're buying a crank anyway. no reason to not go 383 or 396 these days.
If block is being done at shop anyway to bore etc...then they can ck clearances for you and then you can assemble it all. Sometimes best to let them get parts unless they are OK with you getting them. Most shops have preferences.
You might also look at Mahle...they have some nice kits. Between SCAT or Eagle...I'd go SCAT for better machine quality out of the box. Get an internal balanced assy...makes things lots easier. Sometimes best to buy unbalanced assy and let local shop actually do it. Quality is better if it's a good shop.
If 400HP is all you're after..the 350 will get you there with good heads and cam. Stroker just adds some more and makes it easier.
JIM
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
You can never assume bearing clearances will be right. The bore size of the mains for example may be within tolerances..but with a tlerance stack up between the bores, the crank and the bearings it could be anywhere.
If you're buying a crank anyway. no reason to not go 383 or 396 these days.
If block is being done at shop anyway to bore etc...then they can ck clearances for you and then you can assemble it all. Sometimes best to let them get parts unless they are OK with you getting them. Most shops have preferences.
You might also look at Mahle...they have some nice kits. Between SCAT or Eagle...I'd go SCAT for better machine quality out of the box. Get an internal balanced assy...makes things lots easier. Sometimes best to buy unbalanced assy and let local shop actually do it. Quality is better if it's a good shop.
If 400HP is all you're after..the 350 will get you there with good heads and cam. Stroker just adds some more and makes it easier.
JIM
If you're buying a crank anyway. no reason to not go 383 or 396 these days.
If block is being done at shop anyway to bore etc...then they can ck clearances for you and then you can assemble it all. Sometimes best to let them get parts unless they are OK with you getting them. Most shops have preferences.
You might also look at Mahle...they have some nice kits. Between SCAT or Eagle...I'd go SCAT for better machine quality out of the box. Get an internal balanced assy...makes things lots easier. Sometimes best to buy unbalanced assy and let local shop actually do it. Quality is better if it's a good shop.
If 400HP is all you're after..the 350 will get you there with good heads and cam. Stroker just adds some more and makes it easier.
JIM
If your going to build a 383 go with the 6 inch rods and crank to go with it and then you can internally balance the rotator.
The scat I beam 6 inch rods with 7/16 bolts have a lot of cam clearance and pan rail clearance,
As Jim mention the Mahle power pack piston kit is a great value and quality.
There are a lot cheap kits out there where the rods are not even a stroker rod HMMMMMMMMMMMMMMMMM
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
As posted elsewhere, Eagle has real QA issues especially with their cast cranks. I won't do business with Eagle after returning a crank multiple times for unacceptable taper on the journals. Scat has been prefect every time.
Best buy by far is an internally-balanced ***'y; yes, the shop will need to touch it up and this costs $$, but it's a certainty that it *can* be balanced. At that power level you have a tough decision to go cast or forged; cast/hypereutectic is fine as long as you have NO PLANS to use power-adders. If you can afford it, forged offers you more options later if you're looking for more power.
Make sure you have a completed design before you order *anything*. Take the block to the shop first to have them clean/flux/pressure test and measure. They'll tell you what it will clean up at and then you're ready to order your ***'y. A 396 is significantly more work for the 13 CID due to reduced clearances, where a 383 is pretty much a bolt-together operation with the right parts.
No reason to consider reusing your 350 crank/rods - by the time you get the machine work done you'll have spent MORE money for LESS CID...not a good deal.
Be clear with the machine shop that you want to do the final assembly, and be clear on what that means. You'll want the shop to install the cam bearings, oil passage plugs, block plugs, head pins, etc. Keep in mind that if you assemble it you are 100% accountable for the engine - if they make a machining mistake and you don't catch it...it's your fault.
Best buy by far is an internally-balanced ***'y; yes, the shop will need to touch it up and this costs $$, but it's a certainty that it *can* be balanced. At that power level you have a tough decision to go cast or forged; cast/hypereutectic is fine as long as you have NO PLANS to use power-adders. If you can afford it, forged offers you more options later if you're looking for more power.
Make sure you have a completed design before you order *anything*. Take the block to the shop first to have them clean/flux/pressure test and measure. They'll tell you what it will clean up at and then you're ready to order your ***'y. A 396 is significantly more work for the 13 CID due to reduced clearances, where a 383 is pretty much a bolt-together operation with the right parts.
No reason to consider reusing your 350 crank/rods - by the time you get the machine work done you'll have spent MORE money for LESS CID...not a good deal.
Be clear with the machine shop that you want to do the final assembly, and be clear on what that means. You'll want the shop to install the cam bearings, oil passage plugs, block plugs, head pins, etc. Keep in mind that if you assemble it you are 100% accountable for the engine - if they make a machining mistake and you don't catch it...it's your fault.
Drifting
Joined: Apr 2002
Posts: 1,720
Likes: 19
From: Manhattan Beach Ca
My Eagle ended up interfering with new forged pistons I bought even though the pistons were specifically for a 383. It didnt interfere with KB Hypers. Not sure if piston maker is to blame or crank. Just shows you need to check everything.
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Just what part of China do you return your out of tolerance Eagle parts 
Where is the Eagle factory anyway ?
My buddy had to eat a 4 inch Eagle crank that wasn't straight, I then decided to do the right thing and buy a Callies crank. The crank was right on the money in every department. Scat is OK too but I'd spend another few bucks and buy a crank you don't have to worry about.
Where is the Eagle factory anyway ?
My buddy had to eat a 4 inch Eagle crank that wasn't straight, I then decided to do the right thing and buy a Callies crank. The crank was right on the money in every department. Scat is OK too but I'd spend another few bucks and buy a crank you don't have to worry about.
