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406 rotating assembly

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Old Dec 11, 2005 | 08:21 PM
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Default 406 rotating assembly

I will be putting together the rest of my 406 hopefully sometime in the near future. I haven't decided on what pieces yet, but I'm leaning towards forged. It won't be seeing any track time but I want it to be solid.

Any recommendations on where to pickup a reasonably priced forged kit?


Thanks
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Old Dec 12, 2005 | 12:05 AM
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No need to go forged with a street car. Look at Scat or Eagle with an internal balance. You will be able to get a full rotating assembly through cnc motorsports or racers outlet on ebay for less than $1250.
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Old Dec 12, 2005 | 12:31 AM
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This post is interesting to me.I just picked up a real nice 400 4 bolt main block,crank and rods.I would like to build a motor in the 375-400 hp.range.Without having a whole lot of money,I was hoping to use the stock cast rotating assembly.Is that pushing the limit.Should I also go for a nice forged assembly?When I put this motor together,I want to do it right the first time.Maybe I should try to come up with the extra cash to be on the safe side.Hoping you motorheads will chime in.


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Old Dec 12, 2005 | 12:41 AM
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Originally Posted by BLACKHORSEVET
This post is interesting to me.I just picked up a real nice 400 4 bolt main block,crank and rods.I would like to build a motor in the 375-400 hp.range.Without having a whole lot of money,I was hoping to use the stock cast rotating assembly.Is that pushing the limit.Should I also go for a nice forged assembly?When I put this motor together,I want to do it right the first time.Maybe I should try to come up with the extra cash to be on the safe side.Hoping you motorheads will chime in.


An internally balanced Scat, Eagle or combination of both will EASILY good for that. I personally have had good luck with Scat cranks and Eagle rods, but not saying they are any better than any other. I've used a Scat crank with Eagle SIR I beam rods and Keith Black pistons on a 400 and my machine shop found it very easy to internally balance without having to add expensive mallory metal.

By the way, the stock crank should be fine, but it may be more cost effective to go aftermarket if you have to have the stock crank ground. Also, the stock rods are 5.565". You do not want to reuse those and if you did you could almost pick up a set of Eagle or Scat rods for what it cost to recondition the stock ones. You will want to go with a 5.7" or 6" rod.

Last edited by 79VetteMike; Dec 12, 2005 at 12:46 AM.
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Old Dec 12, 2005 | 01:03 AM
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Originally Posted by 79VetteMike
An internally balanced Scat, Eagle or combination of both will EASILY good for that. I personally have had good luck with Scat cranks and Eagle rods, but not saying they are any better than any other. I've used a Scat crank with Eagle SIR I beam rods and Keith Black pistons on a 400 and my machine shop found it very easy to internally balance without having to add expensive mallory metal.

By the way, the stock crank should be fine, but it may be more cost effective to go aftermarket if you have to have the stock crank ground. Also, the stock rods are 5.565". You do not want to reuse those and if you did you could almost pick up a set of Eagle or Scat rods for what it cost to recondition the stock ones. You will want to go with a 5.7" or 6" rod.

Good information here.Can someone explain what the difference would be with the 5.7"-6" rods?Does that just depend on what crank is bought?Thanks
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Old Dec 12, 2005 | 01:22 AM
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Originally Posted by BLACKHORSEVET
Good information here.Can someone explain what the difference would be with the 5.7"-6" rods?Does that just depend on what crank is bought?Thanks
Some cranks will internally balance with a 5.7" rod and others will internally balance with a 6.0" rod. Internally balancing may be overkill, but that's the only way I go. A longer rod theoretically produces more torque and will dictate which pistons you can use. Consider that the stroke of a 400 crank is 3.75. Half of that is 1.875". Add that to 5.7 and you have 7.575". Subtract that from 9.025", which is a standard deck height-if it has not been decked- and you have 1.45".You will need a piston with a 1.45" deck height for a 5.7" rod(Keith Black shows 1.433). Keep in mind that if your block is zero decked, you can subtract .025 from that number, giving you 1.425". The piston deck height for a 6" rod will be 1.15" on an undecked block. The valve relief, dish or dome in the piston will determine your compression ratio-along with your heads and head gasket of course. Other factors are involved here, so this is just general info to get you started.

Last edited by 79VetteMike; Dec 12, 2005 at 01:26 AM.
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Old Dec 12, 2005 | 05:04 AM
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Forged everything, do it right the first time. That way you won't have to worry when you decide to juice it up in the future.
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Old Dec 12, 2005 | 08:22 AM
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79VetteMike

Thanks very much for posting all that 400 info. I too have been looking for all those statistics.
Eddie
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Old Dec 12, 2005 | 08:31 AM
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Originally Posted by blctalon
I will be putting together the rest of my 406 hopefully sometime in the near future. I haven't decided on what pieces yet, but I'm leaning towards forged. It won't be seeing any track time but I want it to be solid.

Any recommendations on where to pickup a reasonably priced forged kit?


Thanks
no track time ,,but do you drive hard ????
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Old Dec 12, 2005 | 09:53 AM
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Originally Posted by BLACKHORSEVET
Good information here.Can someone explain what the difference would be with the 5.7"-6" rods?Does that just depend on what crank is bought?Thanks
To add to what Mike wrote, the "difference" is in the crank counterweights. The 6.0 crank's counterweights are cut down to clear the piston slipper skirt. If you try to use 6.0 rods on a 5.7 crank, the pistons will likely not clear the counterweights. The counterweight difference is also the reason that it is easier (cheaper) to internally balance a 5.7 rod crank since you have more mass to start with. Just providing the abbreviated version.
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Old Dec 12, 2005 | 04:26 PM
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Originally Posted by gerry72
To add to what Mike wrote, the "difference" is in the crank counterweights. The 6.0 crank's counterweights are cut down to clear the piston slipper skirt. If you try to use 6.0 rods on a 5.7 crank, the pistons will likely not clear the counterweights. The counterweight difference is also the reason that it is easier (cheaper) to internally balance a 5.7 rod crank since you have more mass to start with. Just providing the abbreviated version.
Dunno 'bout that? ... I've found it's the other way 'round. Also, in addition to 5.7 piston's longer cd ... I've found typical 5.7" 400 piston's SKIRT is visably longer than typical 6" 400 piston's. Long rod cranks have larger counterweights ... 6" rod moves piston farther away than 5.7 ... often cannot use 5.7 on a 6 crank. That's what I've found ... your results may vary.
Originally Posted by BLACKHORSEVET
This post is interesting to me.I just picked up a real nice 400 4 bolt main block,crank and rods.I would like to build a motor in the 375-400 hp.range.Without having a whole lot of money,I was hoping to use the stock cast rotating assembly.Is that pushing the limit.Should I also go for a nice forged assembly?When I put this motor together,I want to do it right the first time.Maybe I should try to come up with the extra cash to be on the safe side.Hoping you motorheads will chime in.
For street-only 375-400hp sbc400 ... OE crank AOK no problem. Suggest 5.7 or 6 rod and appropriate piston to fit AND achieve reasonable compression ratio with WHATEVER heads you plan to use ... a 400 block bored +30 with flattops will make about 9.8:1 CR with OE 76cc heads.

Do use a CR calculator as you plan a motor ... this one works good:
http://www.campbellenterprises.com/R...o%20calculator

BTW ... if you need a set of pistons for a sbc400-406 ... I have new set of liteweight thirty-over SpeedPro skirt-coated flattop H122CL30 and new SpeedPro Moly rings ... for 6" rod 400/406 ... makes 9.8:1 CR w/ OE 400 heads. Bare piston weighs 461g, pin 105g. Pistons, pins, locks, support rails, ringpak All new never run ... I'll take $290 for pistons, pins & rings and ... depending where you are in USA I'll pay FedEx ground shipping ... and NO I won't sell cheaper.
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Old Dec 12, 2005 | 05:18 PM
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Jackson,
Appreciate the offer on the pistons,but right now I need to store this block for awhile because I don't have the money to build it.Also apreciate the extra tidbits of information.I'm still uncertain about the 5.7-6.0 rods.Is there a better choice between the two? Seems I've heard of more people using the 6.0.I also don't have the heads,so need to go with an aftermarket brand.Looks like a small combustion chamber will put the cr.up too high with flat tops.
The info is really helping me figure things out.And others also.Chime in motorheads !!!!!!!

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Old Dec 12, 2005 | 05:49 PM
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Originally Posted by BLACKHORSEVET
Jackson,
Appreciate the offer on the pistons,but right now I need to store this block for awhile because I don't have the money to build it.Also apreciate the extra tidbits of information.I'm still uncertain about the 5.7-6.0 rods.Is there a better choice between the two? Seems I've heard of more people using the 6.0.I also don't have the heads,so need to go with an aftermarket brand.Looks like a small combustion chamber will put the cr.up too high with flat tops.The info is really helping me figure things out.And others also.Chime in motorheads !!!!!!!
If you're going w/ aftermarket heads ... get 64cc chambers and run dish/inverse dome/reverse dome pistons ... 6" rods my preference.
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Old Dec 12, 2005 | 06:30 PM
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Hey guys, thanks for the posts. I think I'm pretty much decided on the forged assembly. I might give it hell every once in a while and I don't want it falling apart! I'm building an engine that was on chevyhiperformance.com a while back. It was a 406 with AFR competition 180cc intake runners and 64 cc combustion milled to 68cc. I think they used a -22 pistons. This combination made 490 horsepower and 524 lbs torque all under under 5600 rpms on 87 octane. They used a scat 9000 crank, but I think the rods and pistons were forged. I orderd the heads in Septemeber and the wait was quite long, though I should have them this month.

As for the kit. I'm talking to the guy I actually ended up going through to get the heads. Paul and Nick over at http://www.treperformance.com I found them on ebay orginally. They seem to specialize in mainly Ford stuff, but I talked to them when I ordered the heads and they said they could hook me up with other stuff I might need. Their price seems reasonable compared to other online sales. Now I just gotta save up money again.

Lates
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Old Dec 12, 2005 | 08:59 PM
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Internally Balanced SCAT 9000 Series Crank
SCAT 6.0" H-beam rods with 7/16" Cap Screws
SRP Forged Pistons, flat top, 424g
Speed Pro File-Fit Rings
Speed Pro H-14 main and rod bearings

100+ Drag strip passes, 7300rpm, 12000 street miles and still rocking.

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Old Dec 12, 2005 | 09:29 PM
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Hey blctalon,
Do you have a link,or know where I can get that article on the 406 buildup?That sounds like a h*lluva motor.

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Old Dec 12, 2005 | 11:18 PM
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http://www.chevyhiperformance.com/te...imp/index.html

I pmed you too.

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