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I know u guys hear these alot but i havent found a for sure answer yet. What is the difference between putting a 5.7 or 6.0 rod in a 400? Also i hear they are very skeptic as in keeping cool and if you rev em just once ur done? Are you able to fill the bottom and does it work and stay cool? Any body have experience with these? Deciding what to do with mine, any info is appreciated
 

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the rods

there can be a clearence issue with the cam with either 5.7 or 6.0 rod , but its nothing to stop you from doing this. Just has to be checked. A rod with that uses just a bolt that threads into the rod instead of the typical bolt/nut combo helps eleviate clearance issues at the cam , which you could use a small base circle cam to correct this also. The block is gonna need some grinding in the area of the bottom of the cylinders , maybe the pan rails too. Nothing to stop you from using a 5.7 or 6.0 rod though.

My engine builder pal tells me , he can usually do a circle track engine using the 400 block and get 2 seasons out of it with heavy use. He does a few tricks to the deck with pipe plugs , he uses big compression , 14-15/1 so he gets some cracking in the area of the mains and cracking on the deck between coolant holes in most cases.

I've saw some engines built with 400 blocks get tortured and never heard of them having a problem with RPM. I had one myself that got hot one time and it smoked after and lost power. Prolly a low pour using block filler would help in that area. I was 19 and didn't know better.
 

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I agree with levisnteeshirt except the part about clearancing the oilpan rails. That only has to be done when stroking a 400 with a 3.85 and larger stroke crank
 

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I agree with levisnteeshirt except the part about clearancing the oilpan rails. That only has to be done when stroking a 400 with a 3.85 and larger stroke crank
x2 on both. i myself am running a 400 sbc with a half filled block and amost 14-1 comp with N2O. the main thing is to run an oil cooler cause the bottom end gets cooled by oil not water. alot of people over look oil coolers but in the 400's its almost a must if you want to make big power and drive on the street. i drive my car on the street and it normally runs about 180-185* i have an oil cooler with an 8" electric fan running on it. if your goiiing to go this route i would strongly sugest you dont over look this.
 

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Discussion Starter #6
so

you can run 5.7 rods in a 400 and it wouldn't matter? Seems to me you would have to do something different for the different length rods
 

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The crank, rods, and pistons all need to agree. If you're using a 5.7" rod, you need different pistons. GM did not make any, but there are plenty of aftermarket suppliers who do. It's not too tough to figure out, but you do have to make sure they are all compatible.

The simplest solution is to buy a complete rotating assembly from a supplier. It will have all compatible parts (crank/rod/piston), and usually you can get them already balanced. try http://www.flatlanderracing.com http://cnc-motorsports.com http://www.sdpc2000.com or even jegs/summit. After that, all you have to do is get your block machined (typically you're going to need at least a little overbore, so have your machine shop look at the block and tell you what piston oversize you need to buy) and do the assembly.

If you want to 'roll your own' then you have to do the math to figure out the right crank/rod/piston combination.

The standard deck height on a SBC is 9.025" (give or take) so that's the goal. If you use a 5.7" rod, and a 3.75" stroke crank, that's 5.7 + (3.75/2) = 7.575", and 9.025 - 7.575 = 1.45, so IN THEORY you would need pistons with a 1.45" pin height. In practice, the deck height is not exactly 9.025 (and/or you deck the block so it's 9.00 or something) and you need to worry about tolerance variations, and your quench distance. You want to aim for .020-.040 (somebody check me here) distance between the piston and the head for best mixture burn and avoiding pinging. So...if you use a .032 thick head gasket, and aim for the pistons being flush with the deck, all that holds. If you want/need a different head gasket thickness, (or crankshaft stroke, or deck height) you need to adjust the pin height accordingly.
 

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The crank, rods, and pistons all need to agree. If you're using a 5.7" rod, you need different pistons. GM did not make any, but there are plenty of aftermarket suppliers who do. It's not too tough to figure out, but you do have to make sure they are all compatible.

The simplest solution is to buy a complete rotating assembly from a supplier. It will have all compatible parts (crank/rod/piston), and usually you can get them already balanced. try http://www.flatlanderracing.com http://cnc-motorsports.com http://www.sdpc2000.com or even jegs/summit. After that, all you have to do is get your block machined (typically you're going to need at least a little overbore, so have your machine shop look at the block and tell you what piston oversize you need to buy) and do the assembly.

If you want to 'roll your own' then you have to do the math to figure out the right crank/rod/piston combination.

The standard deck height on a SBC is 9.025" (give or take) so that's the goal. If you use a 5.7" rod, and a 3.75" stroke crank, that's 5.7 + (3.75/2) = 7.575", and 9.025 - 7.575 = 1.45, so IN THEORY you would need pistons with a 1.45" pin height. In practice, the deck height is not exactly 9.025 (and/or you deck the block so it's 9.00 or something) and you need to worry about tolerance variations, and your quench distance. You want to aim for .020-.040 (somebody check me here) distance between the piston and the head for best mixture burn and avoiding pinging. So...if you use a .032 thick head gasket, and aim for the pistons being flush with the deck, all that holds. If you want/need a different head gasket thickness, (or crankshaft stroke, or deck height) you need to adjust the pin height accordingly.
Typical quench goals are in the .035"-.045". There are those who have run tighter but if you're not REALLY familiar with setting piston-to-cylinder wall clearances (because of piston rock) then I don't recommend going any tighter. "Witness" marks on the pistons and heads are ok but if they "Kiss" it causes some REAL UGLY outcomes!!

The easiest way to get good quench is to shoot for a "Zero Deck" and use a typical .039" Felpro head gasket. :yes:
 

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One of my 400's was half filled and ran cooler than my .060" over 350.
That engine was a factory 4 bolt (the ones everybody says are no good) it saw over 8000 many times. I've gone thru about 4 blocks in the past 10 years, but the amount of abuse my stuff sees is probably far greater than most of you would be doing. Dyno pulls, testing parts, and racing weekly are kinda hard on stuff, and when street driving with 4.30's it sees a lot of rpm even while cruising.
 

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My buddies 400 is filled to water pump holes.So far it hasn't got hot once.We first fired the engine we had a thermostat stick shut and it got to 230.We put a new 180 thermostat in it and it stays about 200 degree's.

That's with a stock water pump,Flex fan and 3 core radiator.Also steam holes in the heads and the correct headgaskets.

It has 5.7 powder metal rods and matching flat top pistons.Standard base circle comp cams cam also.

It seemed to make good torque.And alot of smoke to boot!:no:
 

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My suggestion would be to read Smokey Yunick's "Power Secrets" book and Grumpy Jenkins book and Small block chevy performance book with Joe Sherman in it. This will give you all the info you need regarding running long rods. In my last 400 I ran 5.7 rods, my latest one I got 6.0 rods. Never had any overheating issues.
 

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I ran a 400 sbc on the street for a couple years till the oil pickup fell off mid pass at the track (always weld the pickup!) and trashed the crank. I used the 5.7 rods and flat tops for around 11.4cr. With a big hydraulic roller and some dart pro 1 215s it ran very good and never got over 190, even in traffic. I think a lot of people give 400s a bad rap who dont have much experience with them.
 
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