Okay I have a block and a 440 stock stroke crank that's already been cut 10/10 just laying around. So if I had that crank grinded down to build a 451 and had the rod journals cut down to 2.20 and maybe using a 6.700 or 6.800 rod would the off shelf piston of 1.32 compression height still work

offset grinding the crank to 3.90 (2.20 rod pin) stroke works great with a 6.7" rod and 1.32CH if I'm not mistaken, or atleast the math works great.

the thing that keeps me hesitant from the doing the same with a crank I have sitting around, is that the rods I've seen are chevy width on the big end. the rod side clearance is large.

for ~ $750 you can buy a crank that is designed to work with the chevy rods...

Call KB, United Technology, tech. help for your correct answer 1-800-648-7970
Are you planning on staying with the stock stroke or offset grinding it down to 2.200 rod journal to make it have 3.90 stroke?
I like those 3.90 stroke motors in both the 440 and 400 blocks
I have one in the shop that I built for a customer back in the early 2000 that he never picked up, 400 block with a forged steel 440 crank with stock stroke and blueprinted LY rods, it made right at 490 HP at 5500 RPM on CA pump swill before splitting a cylinder due to massive casting shift on the driver side cylinders towards the motor mount side leaving the camshaft side really thin
I replaced the block and called him, family and legal problems prevented him from picking the motor up
As far as the rod length and compression height I can't answer about the piston comp. height but the 6.800 and 6.00 long BB Chevy rods both work good in 400 blocks with a lot of different stroke crankshafts, 3.91 to 4.300 strokes

Was thinking about cutting it down to be able to make a 451 just because I have the crank sitting in the garage taking up space

Looks like low deck stroker is the trend this week !

I will go with 6.700 rods and the 14cc dome pistons from 440 source, it will give me 12.66 cr with an 84cc chamber. Hoping for a big bang ! no street driving.

I have a question for Cab....when turning down the counterweight on the crank, do we remove 1/2in the whole width of the counterweight or just the area that is hitting the block inside ?

Thanks and good luck on your build !

Dan

I prefer flat tops, I think they have great flame travel and can still run the number on cheap gas. My 451 with Eddy heads had flat tops and ran 9.89 at 136 with the MP 590 cam, I keep thinking in my head that the rods were 6.76" long, does that sound right? I loved that motor and might build another one just like it.

yeah ! sounds right for a 451 ! and pretty good at 9.89 !!

You’re going to spend more on that crank to make it work than it’s worth in my opinion. For another 3-400 dollars you have a stronger better new crankshaft and whatever cubes you choose up to 511 easily. I used a 4.25/6.7/1.12ch piston. The kits come with shorter 6.535 rod
1.32 piston.
If you do choose to go 451/470/511 they all use a 1.32 piston with a different rod.
The big side clearance of using a Chevy rod is really not an issue.
I went with longer rod for less r/s ratio and a lighter piston. The 1.12 is what’s used in the 499 low decks.

I can't tell you exactly how much needs to be removed from the counterweights on a RB crank, sorry
I think you can chamfer the #5&6 counterweight on the outer edge that faces the #4 main webbing a little bit, maybe a 1/4 inch to make it clear the low deck block main webbing.
A lot of the better machine shops down here in the U.S. cut, trim in a lathe, the outer counterweight ends off to help balance them better with the longer rods so they don' have to drill holes or add heavy metal to get them to balance better

Right at cylinder #1, couterwight is sitting in the block, not all the radius of it....

Kinda what I was thinking my crank has been sitting unprotected for some time now so the condition of it needs to be cut in order for it to clean up.

Thanks all for the replies

Want to build a long rod, big bore 426? The math works, haven't tried it yet thuogh.
7.1 rod (bbc) 383 crank ground to 3.54, 1.120 pin, 4.375 bore piston .030 over 400 block! 2/1 rod ratio, for those that are concerned about it. You would probably need a gasket of .051 and a minimum deck cut.