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Discussion Starter · #1 ·
Hey guys, for any of you that might have read some of my previous thread about the 350///357, I sold that short block. Im having another short block built.
The shop needs me to order my flexplate and harmonic balancer so they can balance the assembly.

I do not know which type to order... these are the ones I have picked out but im trying to make sure.

The balancer is internal balance and the flexplate is external balance so I assume this is wrong.

Brand:Chevrolet Performance

Chevrolet Performance Harmonic Balancers 12551537 - SummitRacing.com

Manufacturer's Part Number:12551537

Part Type:Harmonic Balancers

Product Line:Chevrolet Performance Harmonic Balancers

Summit Racing Part Number:NAL-12551537

Engine Balance:Internal

Safety Rating:Not SFI-approved

Degree Markings:Yes

Outside Diameter (in):6.750 in.

Harmonic Balancer Material:Cast iron

Harmonic Balancer Construction:Steel

Harmonic Balancer Finish:Natural

Mounting Hardware Included:No

Quantity:Sold individually.

Notes:Designed for timing pointer in the 2 o'clock position.






Brand:Hays
http://www.summitracing.com/parts/hay-10-025

Manufacturer's Part Number:10-025

Part Type:Flexplates

Product Line:Hays Heavy-Duty Flexplates

Summit Racing Part Number:HAY-10-025



UPC:084041100257

Ring Gear Tooth Quantity:168-tooth

Rear Main Seal Style:1-piece

Engine Balance:External

Flexplate Material:Steel

Safety Rating:SFI 29.1

Quantity:Sold individually.

Notes:With counter weight.
 

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What is the description of your crank?
The crank is usually intended to be run either internally or externally balanced, and sometimes can differ from front to rear, but without knowing that you are just guessing on what parts to get. The balance shop should be able to give you an idea, but they may need to spin the assembly to find out.
 

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Discussion Starter · #4 ·
What is the description of your crank?
The crank is usually intended to be run either internally or externally balanced, and sometimes can differ from front to rear, but without knowing that you are just guessing on what parts to get. The balance shop should be able to give you an idea, but they may need to spin the assembly to find out.

the block is a 1pc rear main seal 4bolt roller provisioned block. The crank is GM STEEL
 

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Discussion Starter · #6 ·
One good thing is the bolt circles/patterns differ between the two: smaller circle for the 1-piece crank and larger for the 2-piece "traditional" crank. Makes inadvertently using the wrong one impossible.
Okay well Im going to buy the ones I had listed and ship them directly to the machine shop.
After taking my previous short block to the shop and hearing him tell me the pistons where .043-.047 in the hole I decided to just sell the thing and start over.

Im having this one built with D cup keith black hypers 1.561 comp. height.
Keith Black KB Performance Pistons KB142-030 - SummitRacing.com and a decked block for
.010 piston to deck clearance.
Its a 4bolt instead of 2, steel crank, lt1 or X rods with arp rod bolts. All balanced. So im happy! Should be far better than the previously purchased short block. Ill post pictures as soon as I get it at my door in the crate. Gonna take 4 LONNG weeks though!
 

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Okay well Im going to buy the ones I had listed and ship them directly to the machine shop.
After taking my previous short block to the shop and hearing him tell me the pistons where .043-.047 in the hole I decided to just sell the thing and start over.

Im having this one built with D cup keith black hypers 1.561 comp. height.
Keith Black KB Performance Pistons KB142-030 - SummitRacing.com and a decked block for
.010 piston to deck clearance.
Its a 4bolt instead of 2, steel crank, lt1 or X rods with arp rod bolts. All balanced. So im happy! Should be far better than the previously purchased short block. Ill post pictures as soon as I get it at my door in the crate. Gonna take 4 LONNG weeks though!
Ayuh,.... Does this new block have the staggered starter bolt pattern,..??

Ya Need it to use the 168 tooth flywheel/ flexplate...
 

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Okay well Im going to buy the ones I had listed and ship them directly to the machine shop.
After taking my previous short block to the shop and hearing him tell me the pistons where .043-.047 in the hole I decided to just sell the thing and start over.

Im having this one built with D cup keith black hypers 1.561 comp. height.
Keith Black KB Performance Pistons KB142-030 - SummitRacing.com and a decked block for
.010 piston to deck clearance.
Its a 4bolt instead of 2, steel crank, lt1 or X rods with arp rod bolts. All balanced. So im happy! Should be far better than the previously purchased short block. Ill post pictures as soon as I get it at my door in the crate. Gonna take 4 LONNG weeks though!
Sounds good!

You likely are aware of this already, but your KB hypers require a wider-than-normal top ring gap. More: KB Pistons for Automotive Applications
 

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Discussion Starter · #9 ·
Sounds good!

You likely are aware of this already, but your KB hypers require a wider-than-normal top ring gap. More: KB Pistons for Automotive Applications
Yeah I saw the "special instructions" for the pistons. I will mention this to the shop but hopefully they are aware.

I do not know about a "staggered starter bolt pattern"
I will call and ask.
 

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Yeah I saw the "special instructions" for the pistons. I will mention this to the shop but hopefully they are aware.

I do not know about a "staggered starter bolt pattern"
I will call and ask.
You will need to match the flexplate/flywheel ring gear tooth count to the type of starter you want to use.

The larger flywheel has 168 teeth (about 14" OD) , and uses a starter w/offset mounting holes.

The smaller flywheel has 153 teeth (about 12-3/4" OD) and uses the starter w/the mounting holes straight across from each other.

Most all blocks are provisioned w/holes to mount either starter, but check to be sure that you have the holes and that they aren't stripped or broken.

Here is are some photos.
 

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All SB Chevy engines with a 1-piece rear seal are internally balanced. They are equipped with a counter-weighted flex plate. The counter weight on the flex plate is to compensate for a rear main that does not have a counter weight. The counter weight on the flex ,plate does not mean the engine is "externally balanced".

Always use a neutrally balanced harmonic damper on a engine that is internally balanced. I used a pioneer 872021 damper. It is 6.100" O.D. and is SFI 18.1 approved.

Why would anyone use hyper-eutectic cast pistons in a high performance engine when eutectic forged pistons are available?
 
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