Transam.82

I'm going to bore and stoke my ZZ4 crate to a 383, but I'm slightly confused on which rotating assembly to get. If I bored the engine .30 over would actual engine CID be 383 or 380? And what would include .30 over pistons and rings right? What about rod length and engine stroke? I'm ordering through Summit and those are the questions I don't know the answer to, in order to make sure I'm ordering the right parts.

Apeiron

If it's a brand-new block, don't bother boring it. Actual CID doesn't make any difference to anyone, so just keep calling it a 383 regardless of the bore. Stroke has to be 3.75" to make it a 383. Stick with 5.7" rods, in street engines there's not enough benefit in anything longer to make it worth the hassle.

88gta3508

From what I learned.. it is much harder to balance the rotating assembly with 5.7 rods
Also the 6.0 combo is much lighter and less rotating weight... Equals power & quicker reving

Apeiron

No

Depending on part selection there can be some weight savings, and the longer rod gives longer dwell at the top of the stroke. There's also reduced longetivity and increased rod angle, poorer ring sealing, and generally increased cost.

five7kid

iTrader: (14)

If you bored it .30" over, you'll have scrap metal. The most the typical factory SBC block can be bored is .060" over.

88gta3508

Sorry its way more complicated then you saying NO... 6.0 rods have a better bob weight ratio over 5.7 rods Also the shorter 5.7 rods on a 383 conversion.. have been proved to have incorrect thrust angle on the piston. lingenfelters testing states 5.85 rods will be the best combo for a 383.. 6.0 rods have gained around 25 hp over 5.7 rods

Apeiron

It's exactly that complicated. Start balancing your cranks yourself and you'll see.

Yes, there's lots of monkey-spank about the superiority of long rods. It's all true on high-performance engines, and all not worth the effort and expense on street builds.