Rotating Assembly Details from AD Performance

Indycars · Jun 7, 2010

I had this email conversation with Brian Adams of ADPerformance and I'm having trouble understanding the details. Below is the condensed version of the emails between us.
Link to the rotation assembly in question:
http://www.adperformance.com/index.php? ... cts_id=673
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Rick Said:

I need more info about your Scat 4340 Forged Competition Rotating Assembly for $969.00.

- Scat part number for the crankshaft?
- Is this crank internal or externally balanced?
- I can't find specs for the piston options. What ring spec are used? Are any "file to fit" rings?
- Mahle Coated with Rings.....are these pistons Forged?

Thanks!
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Brian Said:

Thank you for your inquiry.

The crank part number can be different if a 6" rod is selected but the base level is 4-350-3750-5700 and is external balance. The 6" rod option is a 4-350-3750-6000 and is internal balance. Both are unbalanced kits at that price.

The basic kit is crank, rod and pistons as listed, no rings are included. Most of our plasma moly ring sets are available as a file fit.

Mahle's pistons are forged, the only piston we carry that is not is a KB.

Brian Adams
http://www.ADperformance.com

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Rick Said:

Thanks for getting back with me!!!

Could you confirm that the crank for 5.7 rods is externally balanced???
When I search the Scat catalog for 4-350-3750-5700 I find the following.

Part Number: 4-350-3750-5700
Short Number: 435050
Description: 350 2-PC REAR SEAL
Stroke: 3.750
Rod Length: 5.700
Rod Pin: 2.1000
Weight: 52
Tech Notes: Internal balance

When selecting "Mahle Coated, with Rings" piston option, are the rings "File to Fit" or "Standard"???

Thanks again!

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Brian Said:

I'll defer it to the manufacture but speaking from experience a short counterweighted Scat 3.75 stroke can be difficult to balance internal.

Mahle's rings are a file fit ring generally.

Brian Adams

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My questions are:

- Is there a reason why the rotating assemble with 6" rods would be easier to balance??? Would it be the lighter pistons with the shorter compression height???
- What does he mean by "short counterweighted" and does he make sense???

I would like to have an internally balanced engine, if I ever have to replace a balancer or flex plate it won't be necessary to disassemble the engine to re-balance. Also I'm leaning towards the 5.7" rods so the wrist pin does not end up in the ring groove, this will be a street engine.

If I buy the individual components what do I need to know??? It seem I've read about having trouble balancing randomly selected components. I'm reading Reher-Morrison "Championship Engine Assembly" Book, maybe all my questions will be answered if I just keep reading.

Any input is greatly appreciated.....thanks!!!

Rick

grumpyvette · Jun 7, 2010

My questions are:

- Is there a reason why the rotating assemble with 6" rods would be easier to balance??? Would it be the lighter pistons with the shorter compression height???
- What does he mean by "short counterweighted" and does he make sense???

as the counter weights rotate under the piston skirt theres LESS clearance with a 5.7" connecting rod than a 6" rod provides, so the counter weights tend to be smaller and lighter, crank counter weights on a 6" crank allow far easier balance jobs
maybe a picture helps

I would like to have an internally balanced engine, if I ever have to replace a balancer or flex plate it won't be necessary to disassemble the engine to re-balance. Also I'm leaning towards the 5.7" rods so the wrist pin does not end up in the ring groove, this will be a street engine.

If I buy the individual components what do I need to know??? It seem I've read about having trouble balancing randomly selected components. I'm reading Reher-Morrison "Championship Engine Assembly" Book, maybe all my questions will be answered if I just keep reading.

Any input is greatly appreciated.....thanks!!!

It always seems to costs a bit more up front but its almost ALWAYS cheaper in the long run to buy a BALANCED assembly with the bearings,rings,pistons,rods,crank,damper,flywheel etc FROM A SINGLE SOURCE
Rick

places to shop

http://www.speedomotive.com/

http://ohiocrank.com/

http://www.dougherbert.com/

Indycars · Jun 8, 2010

It always seems to costs a bit more up front but its almost ALWAYS cheaper in the long run to buy a BALANCED assembly with the bearings,rings,pistons,rods,crank,damper,flywheel etc FROM A SINGLE SOURCE

I cannot find an rotating assembly that has exactly what I want, therefore the reason I asked about individual components. Also if its already balanced and I need to fly cut the pistons, then I wasted about $200.....right???

Scat said their crank for the 5.7" rods was internally balanced, but Brian thought it was not. Is this not a black & white question, or is it one of those "Depends" questions???

I don't want to get into a situation where I have to spend extra money to return ship an assembly that is not what I am expecting or just accept something less than I was hoping for.

I emailed Eagle to find out what clearances they used. Their response was "The cranks are ground and the rods are sized to O.E. spec range. The bearings are "off-the-shelf" Clevite77 "P" bearings. Clearance should be within O.E. specifications." So do I have to buy more bearings with 0.001 to possibly get the clearances I need. It just seems that the list of details is never ending and the retailers don't provide enough info to make a good decision.

Ok....the frustration is beginning to show just a little. Thanks for your time!!!

Rick

grumpyvette · Jun 8, 2010

Indycars said:
It always seems to costs a bit more up front but its almost ALWAYS cheaper in the long run to buy a BALANCED assembly with the bearings,rings,pistons,rods,crank,damper,flywheel etc FROM A SINGLE SOURCE

Click to expand...

I cannot find an rotating assembly that has exactly what I want, therefore the reason I asked about individual components. Also if its already balanced and I need to fly cut the pistons, then I wasted about $200.....right???

Scat said their crank for the 5.7" rods was internally balanced, but Brian thought it was not. Is this not a black & white question, or is it one of those "Depends" questions???

when SCAT or almost anyone else says a CRANK is internally balanced what they mean is that its designed to use internally balanced flex plates,flywheels, and dampers , VS the externally balanced components, they do NOT mean its already balanced, and ready for assembly and ready for use as it comes, out of the box!,It means its going to require INTERNALLY BALANCED COMPONENTS, and rods and pistons of the matched weight and length, thats why most cranks will usually say (use with 5.7" or use with 6" rods) depending on the counter weights and clearances.
as that can only be done once the full compliment of components is individually weighed and then the assembly can be balanced, with those components, usually to a tolerance of 1/2-1 gram, a factory balance can be within about 4 grams, from what Ive seen

I don't want to get into a situation where I have to spend extra money to return ship an assembly that is not what I am expecting or just accept something less than I was hoping for.

I emailed Eagle to find out what clearances they used. Their response was "The cranks are ground and the rods are sized to O.E. spec range. The bearings are "off-the-shelf" Clevite77 "P" bearings. Clearance should be within O.E. specifications." So do I have to buy more bearings with 0.001 to possibly get the clearances I need. It just seems that the list of details is never ending and the retailers don't provide enough info to make a good decision.

most manufacturers TRY to match the basic O.E.M. balance specs and clearances, that assumes youll use similar components thru out the rotating assembly, but keep in mind O.E.M. balance specs and clearances are designed to match an operation environment that favors mostly below 4500rpm use so its rarely as exact as you'll get with an aftermarket balance job done to your custom assembly with parts that will rarely weight exactly what the o.e.m. parts did.
the longer 6" rods allow the use of lighter weight pistons that also allow larger counter weights on the crank, making the balance work easier and the crank assemblies stress levels lower, at high rpms

Ok....the frustration is beginning to show just a little. Thanks for your time!!!

Rick

Indycars · Jun 8, 2010

when SCAT or almost anyone else says a CRANK is internally balanced what they mean is that its designed to use internally balanced flex plates,flywheels, and dampers , VS the externally balanced components, they do NOT mean its already balanced, and ready for assembly and ready for use as it comes, out of the box!

I realized that the parts have not been thru the balancing process. I'm assuming when they say (as in the Scat example) that it CAN be balanced internally WITHOUT the extra expense of using a heavy metal. So with this in mind, my question remains.....will the Scat crank for 5.7" rods balance without heavy metal??? I'm not trying to say you should be able to answer this question, but the answer should be attainable somehow before buying.

Maybe I'm making too much out this detail of internal balance with 5.7" rods. It just seems better, in my way thinking, that I would be better off with the wrist pin below the last oil ring groove for durability.

Rick

grumpyvette · Jun 8, 2010

heres scats ph# 310-370-5501
heres their site
http://www.scatcrankshafts.com/

SCAT should be able to tell you the IDEAL bob weight range suggested for that crank

bob weight= connecting rod, piston,piston pin, rings and rod bearings

"So with this in mind, my question remains.....will the Scat crank for 5.7" rods balance without heavy metal???"

the answer depends on the pistons and connecting rods you select and their combined BOB WEIGHT, of the parts you selected will require, during balancing,
but if the parts are similar in total weight, or lighter in weight to OE.M. components you should be able to balance WITHOUT heavy metal

keep in mind SOME forged full floating pin pistons, and many pistons using tapered tool steel piston pins, tend to be lighter than heavy stock cast pistons and press in piston pins and that SOME aftermarket rods even ones 200% stronger than factory connecting rods can be lighter in weight

CHEVY: Cranks
CHEVY SMALL BLOCK & BIG BLOCK FORGED 4340 STANDARD WEIGHT CRANKSHAFTS
SMALL BLOCK CHEVY 350 & 400 MAIN, 2-PC & 1-PC REAR SEAL FORGED
Part No Short No Description Stroke RodLength RodPin Weight
4-350-3000-5700-2" 435005 350 2-PC REAR SEAL, STD WEIGHT 3.000" 5.700" 2.000" 50
4-350-3250-5700 435006 350 2-PC REAR SEAL, STD WEIGHT 3.250" 5.700" 2.100" 50
4-350-3480-5700 435010 350 2-PC REAR SEAL, STD WEIGHT 3.480" 5.700" 2.100" 51
4-350-3500-5700 435020 350 2-PC REAR SEAL, STD WEIGHT 3.500" 5.700" 2.100" 51
4-350-3562-5700 435030 350 2-PC REAR SEAL, STD WEIGHT 3.562" 5.700" 2.100" 51
4-350-3625-5700 435040 350 2-PC REAR SEAL, STD WEIGHT 3.625" 5.700" 2.100" 52
4-350-3750-5700 435050 350 2-PC REAR SEAL, STD WEIGHT 3.750" 5.700" 2.100" 52
4-350-3750-6000 435056 350 2-PC REAR SEAL, STD WEIGHT 3.750" 6.000" 2.100" 53
4-350-3875-6000 435076 350 2-PC REAR SEAL, STD WEIGHT 3.875" 6.000" 2.100" 53
4-350-4000-6000 435086 350 2-PC REAR SEAL, STD WEIGHT 4.000" 6.000" 2.100" 54
4-400-3500-6000 440026 400 2-PC REAR SEAL, STD WEIGHT 3.500" 6.000" 2.100" 55
4-400-3750-5700 440050 400 2-PC REAR SEAL, STD WEIGHT 3.750" 5.700" 2.100" 55
4-400-3750-6000 440056 400 2-PC REAR SEAL, STD WEIGHT 3.750" 6.000" 2.100" 55
4-400-3800-6000 440066 400 2-PC REAR SEAL, STD WEIGHT 3.800" 6.000" 2.100" 55
4-400-3875-6000 440076 400 2-PC REAR SEAL, STD WEIGHT 3.875" 6.000" 2.100" 55
4-400-4000-6000 440086 400 2-PC REAR SEAL, STD WEIGHT 4.000" 6.000" 2.100" 55
4-350-3480-5700-L 435010L 350 1-PC REAR SEAL, STD WEIGHT 3.480" 5.700" 2.100" 51
4-350-3750-5700-L 435050L 350 1-PC REAR SEAL, STD WEIGHT 3.750" 5.700" 2.100" 52
4-350-3800-5700-L 435058 350 1-PC REAR SEAL, STD WEIGHT 3.800" 5.700" 2.100" 52
4-350-3800-6000-L 435065L 350 1-PC REAR SEAL, STD WEIGHT 3.800" 6.000" 2.100" 52
4-350-3875-6000-L 435070L 350 1-PC REAR SEAL, STD WEIGHT 3.875" 6.000" 2.100" 52
BIG BLOCK CHEVY 454 MAIN, 2-PC & 1-PC REAR SEAL FORGED
Part No Short No Description Stroke RodLength RodPin Weight
4-409-4000-6135 440910 409 2-PC REAR SEAL, STD WEIGHT 4.000" 6.135" 2.200" 70
4-454-4000-6135 445410 454 2-PC REAR SEAL, STD WEIGHT 4.000" 6.135" 2.200" 70
4-454-4000-6385 445415 454 2-PC REAR SEAL, STD WEIGHT 4.000" 6.385" 2.200" 75
4-454-4250-6135 445420 454 2-PC REAR SEAL, STD WEIGHT 4.250' 6.135" 2.200" 70
4-454-4250-6385 445425 454 2-PC REAR SEAL, STD WEIGHT 4.250" 6.385" 2.200" 70
4-454-4375-6385 445426 454 2-PC REAR SEAL, STD WEIGHT 4.375" 6.385" 2.200" 70
4-454-4500-6535 445430 454 2-PC REAR SEAL, STD WEIGHT 4.500" 6.535" 2.200" 70
4-454-4250-6135-L 445420L 454 1-PC REAR SEAL, STD WEIGHT 4.250" 6.135" 2.200" 75
4-454-4250-6385-L 445425L 454 1-PC REAR SEAL, STD WEIGHT 4.250" 6.385" 2.200" 70
4-454-4500-6385-L 445430L 454 2-PC REAR SEAL, STD WEIGHT 4.500" 6.535" 2.200" 70

Rotating Assembly Details from AD Performance

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