400 with internal balancing - Team Camaro Tech
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post #1 of 15 (permalink) Old Feb 1st, 10, 12:50 AM Thread Starter
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Jimmie-Retired
 
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400 with internal balancing

I'm wondering if I can retain the original rotating assembly in a 4 bolt 400 SBC(511 block I beleve) and turn 5500-5700 rpm and make 360-375 HP? Could I stay with an original balancer and buy a new externally balanced flywheel? This will not be raced but just want reasonable power. Why rebuild a 350 when I can get the extra 50 c.i. for a $200 builder block. I've thought about the 383 route but the stroker kit alone is $600-$700 and it only nets you 33 extra c.i. What are your thoughts? Car has M21 with a LUK 10 1/2" clutch. I've always like the old addage that there's no substitue for cubic inches. Where would I start looking for the externally balanced flywheel? Thanks.

Jim's '69
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post #2 of 15 (permalink) Old Feb 1st, 10, 04:01 AM
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Jeff
 
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Re: 400 with internal balancing

It takes quite a bit of work (and $ for mallory) to internally bal. a stock nodular 400 crank. You can use stock 350 flywheel and damper if the budget is tight.
The biggest problem I can see is your 4 bolt 400 block, the main webs are very weak were the outer main bolts thread into the block. At the 375 h.p. range it may be OK however, anything much over that you are begging for trouble.....IMHO

1970 RS Z28, 427 small block, fogger, plate and a Liberty Power Brute Super T-10
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post #3 of 15 (permalink) Old Feb 1st, 10, 05:02 AM
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Bill
 
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Re: 400 with internal balancing

Jim,
Your post is a little confusing. In the title you say "internal" balance but then you are looking for an external balance flywheel ??

If the entire rotating assembly is stock GM 400, then you can use the 400 damper and a 400 flywheel, both of which will have a weight built into them. Just about everyone sells 400 flywheels.

As far as running it hard, there are plenty of guys that have run stock 400's for many years and never had problems.

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1971 Chevelle "Heavy Chevy" original owner


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post #4 of 15 (permalink) Old Feb 1st, 10, 05:07 AM
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Steve
 
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Re: 400 with internal balancing

Summit has externally ballanced flywheels for a 400.

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post #5 of 15 (permalink) Old Feb 1st, 10, 05:51 AM
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Rich
 
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Re: 400 with internal balancing

No need to internal balance,even up to 7500rpm.The myth that 4 bolt 400's crack at the main webs is a farce.I have run plenty of them as well as 2 bolts well over 700 hp,and I can tell you flat out,that out will push the head gaskets out or lift the heads off the block before the maiins will fail.If you wanted to know which 400's to stay away from,aviod 1976 and later engines from trucks and vans.The softer metal causes cracks from the head bolts into the cylinders,and there is no real good way to aviod it.
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post #6 of 15 (permalink) Old Feb 1st, 10, 07:05 AM
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Jeff
 
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Re: 400 with internal balancing

Quote:
Originally Posted by RichSchmidt View Post
No need to internal balance,even up to 7500rpm.The myth that 4 bolt 400's crack at the main webs is a farce.I have run plenty of them as well as 2 bolts well over 700 hp,and I can tell you flat out,that out will push the head gaskets out or lift the heads off the block before the maiins will fail.If you wanted to know which 400's to stay away from,aviod 1976 and later engines from trucks and vans.The softer metal causes cracks from the head bolts into the cylinders,and there is no real good way to aviod it.
I fully agree there is no need to internally bal. in such a low h.p. application.
However, there is no myth, no farce, stock 4 bolt 400s are weak-period.
A 2 bolt 400 will outlive a 4 bolt 400 in any high perf. application and the cracks from the coolant passages/cylinders to the head bolt holes will be found on ANY GM 400 block.
I also agree the first place you will see trouble will be the head gaskets, but that is very easily cured with a set of F.P. 1045s.
An "honest" 700 h.p. stock block 400 is very unlikely, it would be a time bomb waiting to happen.
A N/A 700 h.p. 400 will not only brake main webs but also cranks due to the main caps walking around. A nitrous assisted 700 h.p. stock block 400 will split cylinder walls with a quickness also. Been there, done that.

1970 RS Z28, 427 small block, fogger, plate and a Liberty Power Brute Super T-10
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post #7 of 15 (permalink) Old Feb 1st, 10, 05:06 PM Thread Starter
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Jimmie-Retired
 
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Re: 400 with internal balancing

Quote:
Originally Posted by BillK View Post
Jim,
Your post is a little confusing. In the title you say "internal" balance but then you are looking for an external balance flywheel ?? .

Yeah, I screwed that one up. My point was suppose to be can you use the stock crank/rods (400 4 bolt) to make decent power using stock style balancer and using a new flywheel to maintain the external balancing?

Since this is not going to be a track car, I just dont want to spend the money for an all new internally balanced crank/rods.

I can get another 400 builder that is a 2 bolt main(509 i think). The guy is asking $350 but I havent tried to dicker with him. It was running when it came out of an early 70's Caprice according to him. The 4 bolt builder motor is $200 but I think it is in a 78 GMC 2500 Sierra pickup.

Jim's '69
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post #8 of 15 (permalink) Old Feb 1st, 10, 10:40 PM
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mike
 
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Re: 400 with internal balancing

Quote:
Originally Posted by RichSchmidt View Post
No need to internal balance,even up to 7500rpm.The myth that 4 bolt 400's crack at the main webs is a farce.I have run plenty of them as well as 2 bolts well over 700 hp,and I can tell you flat out,that out will push the head gaskets out or lift the heads off the block before the maiins will fail.If you wanted to know which 400's to stay away from,aviod 1976 and later engines from trucks and vans.The softer metal causes cracks from the head bolts into the cylinders,and there is no real good way to aviod it.
I believe its a farce also judging from the many posts I have read with people using 4-bolt main 400's that do just fine in high horsepower applications.

No doubt a 2-bolt 400 with splayed mains is stronger but give me a 4-bolt over a 2-bolt any day.

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post #9 of 15 (permalink) Old Feb 1st, 10, 11:02 PM
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AJ
 
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Re: 400 with internal balancing

Quote:
Originally Posted by HOGDADDY View Post
I believe its a farce also judging from the many posts I have read with people using 4-bolt main 400's that do just fine in high horsepower applications.

No doubt a 2-bolt 400 with splayed mains is stronger but give me a 4-bolt over a 2-bolt any day.
If your talking standard 302, 327, 350 bore spacing, yes, give me a 4 bolt any day.
But if your talking 400's, it's an entirely different story.

Main webbings are thin, I've seen a block that had cracked mains and main webbings, it was a 4 bolt, and I've only seen 2-3 400 blocks in my life bare.

CNCblocks had a pretty nasty picture of a 400 block that blew the crank out of the bottom and took the mains with it, I don't know if it was a 4 bolt or not, but it is possible.

The only Mustang I'd ever own is a Fender.

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post #10 of 15 (permalink) Old Feb 1st, 10, 11:27 PM
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mike
 
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Re: 400 with internal balancing

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Originally Posted by ace's68 View Post
If your talking standard 302, 327, 350 bore spacing, yes, give me a 4 bolt any day.
But if your talking 400's, it's an entirely different story.

Main webbings are thin, I've seen a block that had cracked mains and main webbings, it was a 4 bolt, and I've only seen 2-3 400 blocks in my life bare.

CNCblocks had a pretty nasty picture of a 400 block that blew the crank out of the bottom and took the mains with it, I don't know if it was a 4 bolt or not, but it is possible.
I am aware of all those that have been saying all along that 4-bolts are weak in mains but I am still not convinced that they are not suitable for performance builds because over the years I have read just as many posts saying they are ok to use.

My 400 4-bolt main 10:1 has been problem free for many years also.

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post #11 of 15 (permalink) Old Feb 2nd, 10, 05:22 AM
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Gary
 
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Re: 400 with internal balancing

What year is the 509? The earlier ones are the best 400 castings to use IF it's in good shape.
You can almost bet that the truck engine hasn't seen the high side of 4 grand or so, they're pretty strangled from the factory.
At your level, I'd think a 4-bolt would be fine. One trick is to chamfer the bolt holes where they come thru the bottom of the webbing. Putting a radius on the lower edges of the bolt hole rather than leaving sharp bolt threads reduces the chance of a crack beginning in that area.

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post #12 of 15 (permalink) Old Feb 12th, 10, 07:26 PM
Brad
 
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Re: 400 with internal balancing

I also have a 400 4 bolt bare block. Have had me concerns about it being to weak and over heating. Would like to stroke it to a 406 and shoot for around 500hp. Been looking at all kinds build combos, but it still looks like I would be in the $5000 to $6000 for turn key. Not sure if it's worth doing the build or buying one the is already built. Any input you guys have would be helpful.

Thanks!!
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post #13 of 15 (permalink) Old Feb 12th, 10, 07:57 PM
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Re: 400 with internal balancing

My father-in-law has a 400 bored 60 over with 6 inch rods vortec heads,10 to 1 compression,not sure on the cam in a 55 bel air 2 door hard top,373 gears,700r4,very strong,beat a 6.0 GTO,I think the gto was 425 hp,he has had no problems,4 bolt block.
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post #14 of 15 (permalink) Old Feb 12th, 10, 09:12 PM
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Re: 400 with internal balancing

Quote:
Originally Posted by scruffy68 View Post
I also have a 400 4 bolt bare block. Have had me concerns about it being to weak and over heating. Would like to stroke it to a 406 and shoot for around 500hp. Been looking at all kinds build combos, but it still looks like I would be in the $5000 to $6000 for turn key. Not sure if it's worth doing the build or buying one the is already built. Any input you guys have would be helpful.

Thanks!!
More people have problems with 400 blocks than all of the rest of the sbc's put together. That being said, as long as you get the block checked out you can make 600 HP without much worry with a 400 block, I have had several over the years from 400-550 HP.

You could stroke your 400 to a 406 but that would be really expensive without much benefit...you probably meant you will bore it to a 406.

You won't have any problems getting 500 HP from a 400 or even a 350 for 6K or less on pump gasoline.

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post #15 of 15 (permalink) Old Feb 13th, 10, 08:03 AM
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Rich
 
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Re: 400 with internal balancing

I have seen a heckuva lo more then 2 or 3,400's in my life.I have blown up 2 or 3 dozen.I have engines being run by street racerswho ask for a 500 hp engine that can take a 200 shot of nitrous.It never fails that they negotiate a race they shouldn't have and they stack 2 or 3 plates on the engine and rig up a bunch of T fittings in the fuel lines and see if they can make 1200 hp last until close enough to the finish line that they can coast to the win.I never had a factory 4 bolt block fail.Head gaskets are the first victim.I used to O-ring all the high power engines bfore I started using Cometic gaskets but when things get that hot the deck will melt between the bores.Bores get destroyed by melted pistons and inched rings,but the mains have never cracked.Maybe the rumor started when some "know it all"types figured that if 70 pounds of torque on the main caps was good then 100# mut be better.
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