"White Knight"

Alright the question is.....can a piston 4.030 bore designed for a 355 with 6in rod fit anything else? (it's a blower piston -24cc) Would it be able to be used in a 383 set-up? a 3.75" stroke 383 crank would work right?

OldSStroker

No, not without a special length rod. Here's why:

Assume 9.025 stock deck height which is distance from crank centerline to top of block. For the piston top to be flush with the top of the block at top dead center (TDC), the crank throw, which is 1/2 of the stroke, PLUS the rod length PLUS the compression height (CH), which is the distance from the center of the piston pin to the top of the piston, have to add up to 9.025.

So, (3.48/2) crank throw for 350/355 + 6.00 rod length + CH = 9.025. We can solve for CH by rearranging the terms:

CH = 9.025 -6.00 - (3.48/2) or

CH = 9.025 - 6.00 - 1.74 or

CH = 1.285 inches.

In the real world, the block would already have been decked to 9.000, and let's say the piston was .010 down in the hole. Now to figure the CH, you use the same formula with the new numbers:
CH = 9.000 - 6.00 - 1.74 -.010 (piston in the hole) or
CH = 1.250 inches.

Notice the .025 removed from the block and the .010 in the hole require the piston CH to be .025 + .010 or .035 shorter.

Not trying to insult anyone's intelligence with all this, but if you understand the concept, you can do the math on a calculator, and you'll be able to figure out ANY combination.

You can do the math to figure how much shorter a rod you'd need, or how far out of the block that piston would be using the 6.00 rod with a 3.75 stroke.

And the answer is.....???

Eff

Well...... to sum that up, you neglected to mention your compression height.
If you wanted to use that rod and crank setup, assiming your deck height was 9.0, your deck clearence and compression height would have to add up to 1.125.

eg. if you used a .015 deck clearence, you would need a CH of 1.11

thats a good average number for deck clearence. I suppose if your CH was within about .005" either way you would be ok.

"White Knight"

I don't take offence at all. Thanks OldSStroker. I'm still trying to figure it out though.... I started to figure it out, but then i had to go take care of a harrasment case here at work.

"White Knight"

Anyone know where their is a thread that i can see the davantages/disadvantages of using 5.7/6" rods? I know their has been some posts in the past, but i can't find them.