Engine builders Help needed
 

This is a 540 set up i have that blew apart(prior to me). Just trying to figuer out exacally what it is i need. has an odd set up. The Cranks is a Crower 4.250 stroke. The block is a Merlin III 4.500 bore. The odd part is the rod lenght isnt standard its a 6.405. From what i could find out mean the pistons are 1.520 comp. height. Its a 10.2 tall deck. Im assuming the extra rod leanght makes up for it being a tall deck. On JE site the pistons listed were for the 9.8 engine. Can anyone let me know if im headed in the right direction so i can start getting parts
Thanks
Mike

Are you sure about those numbers???
I come up with this: 10.2- 2.125(half of the stroke)- 6.405(length of rod) - 1.520 (comp. height) = .150 This means the piston is .150 below the deck. That doesn't seem right. Are you sure about rod length? That is an odd length.
There are a lot of builders that like to use a tall deck to build a 540. Personally, I think that if you are going to have a tall deck, then use it. Make some inches out of it. To really take advantage of having the tall deck 540, you really need longer rods. You really need a 6.535 rod with that piston. That will leave the piston .020" in the hole. That leaves enough to deck the block to be sure it is square. Hope this helps.
Eddie

Checked the rods twice, It measured .405. Had a machine shop take the piston off the rod and pin out and check some numbers for me. Should i recheck them. Kinda has me baffled also. I was told a 6.385 was the most common rod for the 540.
-Mike

Young i came up with the same .150 though i did somethign wrong with the numbers. Seems there is alot of area missing out for the compression quench rite?
-Mike

Yes the quench is WAY to big. That will make the engine susceptable to detonation. Anything over about .075 is way to much. Ideally, you want .040-.060 including the gasket. You will be close to .200 with a gasket.
Eddie

6.385 is a common rod for a 540, but in a low deck block. The normal setup is a 6.385 rod with a piston with a 1.27 comp. height. Like I said, this is in a low deck.(9.8")
Eddie

Thanks Eddie i got ya. 9.8 deck instea of the .4 large brother of the 10.2 deck. Rod lenght is center to center correct?
-Mike

Yes, the rod is measured from the center of the housing bore (large end) to the center of the pin hole (small end)
Eddie

Thanks thats what i figuerd.
-Mike

Eddie million dollar question. Order 2 sets of rods and stay with same piston. Or do i need rods and pistons.
Thanks
Mike