My 383 stroker has 6" rods. Because I have to tear into it to replace the rings, I was wondering if I should step down a notch.
I want a 383 that will last. I drive the car a lot during the Summer, plus track 1-2 times a month during the season.

I'm not too convinced I'll be doing the 5.7 rods yet. I'd just like to hear the pros and cons, to see if that may sway my decision one way or another.
Also, do I need to get another crankshaft? What else would it need to be replaced, machined, etc...?
THX-Goose

 

Goose, i will give those rods a good home Which crank are you running now?

 

The crankshaft is a Scat large radius, the connecting rods are 4340 H-Bean. I'm not sure I'm going to do this though. I'm just collecting some information first. It's a longshot at this point.

 

I think 6'' is better due to less sidewall pressure
not sure though

I think its more about HOW you build it that rod length though

 

Why spend the $ to do that... doesnt seem worth it IMO.. dunno what youre doing with the motor.. but still.

 

This gets discussed a lot. Many people may be tired of posting thier opinions, so you may not get many responses. Perhaps you should do a search?

My own conclusion is that in general a high rev NA setup benefits from long rods while a SC setup should use a short rod. I have explained my rationale often enough that I prefer not to type it all out again.

However, if I had a suitable set of rods in good conditions I would re-use them whatever the length.

Rich Krause

 

going from a 6 to a 5.700" rod is going to mean a crank change too probably.

I have no idea why you would change, lol.

 

It wasn't quite my idea to change my rods. A friend implied I should do that. I just wanted to know if it made sense or not.
It looks like a bad idea.

 

You'll need new pistons

 

People could argue this all day... the truth is that the power/durability difference between 6" and 5.7" rods is small.
I personally chose 6" rods for my 383 (read too much Smokey Yunick in my life) , but I don't think its really gonna make a big difference.
If you already have 6" rods (or 5.7" rods for that matter) don't bother changing... take the money and put it into somthing else, you'll get better results

 

well the Scat crank should be fine, but:

You need new pistons to go with the shorter rods. On top of that you will have more rod angularity, which in turn will wear out the new piston rings faster. You ever notice that 400 SBC always wear out the bores and rings stupid fast? that's because they have the same long stroke and the shortest small block rod ever. That's a good set up, stay with it. Just get new rings and maybe deglaze the cylinders, that should work.

Bret

 

The funny thing is that many Honda motors run a similar rod ratio to a standard SBC 400, and don't have the same problem with cylinder wall wear.

With regards to the original question, I'd keep the 6" rods unless there was a specific desire to move the rings down on the piston or run a large piston dish (both of which are very valid reasons to run a shorter rod). But, if you don't need to do either of these, I think it'd be a waste of money to buy shorter rods, new pistons, maybe cut the counterweights on the crank (depending on whether or not they're already cut for a 5.7" rod), and then finally rebalance the rotating assembly. That's a lot of money if there's no good reason behind the change.

 

Swapping to a 5.7 from a 6 inch rod is pretty uncommon, most people go the other way. The reduced rod length would translate into a slightly lighter assembly which could have a small rev advantage. (however it requires a different piston with the correct pin height).

the benefits of a longer rod are 3-fold, as other guys said it reduces the loading on the bores. Also the extra length provides more leverage on the crank, giving a slight torque benefit. The real plus is the potential it gives you for ultimate high RPM power. The longer rod because of its geometry allows the piston to dwell longer at top dead center, allowing the combustion process more time to increase cylinder pressure before the piston starts to move back down the bore.

My 383 is a an 80 4-bolt 350 block bored .030 over, it has a forged GM caps, a callies 4340 crank, clevite bearings, 6 inch manley sportsmaster H beam rods with floating pins, JE forged pistons, comp roller cam with .600 (.640 with the 1.7 rockers) moly push rods, comp cams pro magnum roller rockers, comp stud girdles, pro mag lifters, 210 CC fully cnc ported AFR heads with stainless valves, titanium locks and retainers, triple comp springs, victor jr intake, 1 inch spacer with a 750 race demon carb, hooker super comp headers.....whooo outta breath

 

i think that is an incorrect statement, yes the rod itself is lighter but not the whole assembly

the weight of a 5.7" rod piston is much heavier than a 6.0" rod piston.....so actually you are lighter with the longer rod. i know it sounds weird, but i'm sure someone can confirm that

 

I run a 383 (forged Cola 3.75" crank) I was thinking about going to a 5.7" rod from a 6" rod, too (I guess that would mean a new crank). The 5.7" rod has a number of benefits.....lower ring pack, a larger selection of dish pistons, oil ring doesn't float thru the pin hole, and, longer piston skirt.