If I use 5.7 or 6.0 rods in a 400 build up is there clearancing that needs to be done? Also will I need a small base circle cam? I plan on using Eagle H beam rods. But what is the benefit of the 6.0 rod over the 5.7? Where would I need to clearance?

I just assembled a 407 with stock stroke 3.75 SCAT crank, 5.7 H beam rods, and SRP flat top pistons.

I had to grind on the oil pan rail in three places-didn't hit, but they were too close for comfort.

I also had to grind on three of the piston skirts as they barely hit the crank counterweights-quality control problem???

I'm using a simple 282 solid lifter cam and have no conflicts with it.

I prefer the 5.7 as the 6.0 rods require an oil support to the oil scraper package-one more thing for me to mess up and less durable than normal ring package, but countless engines are run that way with no problem.

I ordered the assembly balanced so the grinding on the pistons wasn't very cool. I don't think I took enough off to worry about.

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I just did 5.565" rods with a Hawks racing 383 crank/350 pistons and it hit either the pistons or oil pump just slightly in 7 different places. I just masked off the motor and ground off material from the crank, didnt take to long.

Why the 5.56 rods? Aren't they an odd rod being as short as they are?

Originally posted by Whittaker:
Why the 5.56 rods? Aren't they an odd rod being as short as they are? Those are stock 400 rods....he must of had it in a 350 block, because no clearancing would be needed for a 400 block with 5.56 rods

If you build a SB 400 using stock 350 (5.7) type rods, the ONLY clearancing that is necessary is a slight 45deg grinding on the head of the rod bolts which face the cam (provided you go with a flat tappet cam). NO CLEARANCING OF THE LOWER END OF THE BLOCK IS REQUIRED (400 blocks are FACTORY clearanced).
If you build this same engine using a 6in rod, the required piston will have the wrist pin hole in the oil ring groove. This may be OK for a race engine, but personally, I don't like it for a street/performance engine. Also, clearancing requirements for an aftermarket 6in rod can ONLY be determined by doing trial fitting BEFORE final engine assembly (and before balancing). This trial fitting can be made much easier by having your machineist reduce the size of an old small block wrist pin so that it is just a slip fit in the rod. This makes it VERY easy to triall fit all the rods/pistons/crank/bearings to allow you to establish how much and where clearancing is required.
The ONLY time that I have seen a need to clearance the bottom of a 400 block for rod bolt clearance is when the stroke is increased to 3.85 or more.
If you are building an all around street/performance engine, and using a flat tappet cam, I think you will be plenty satisfied with, and have fewer hassles, if you build it with a good set of 5.7 rods. Over the years, I have built 25-30 SB400s, and all but a couple have had stock, reconditioned, resized 350 rods (2 engines got the std 400 5.565 rods). I even built one 420SB and used small journal 327 5.7 rods. It's still running strong in my jet boat.
If you use ANY aftermarket rod (something with a configuration which is different from a stock 350 rod), then it will be imperative to check for clearance by doing a trial fit/assembly.