Anyone with experience please comment {especially the engine builders from around the country that visit this site}.

For a 4.25" stroke you have a choice of building the engine using either the stock BBC 6.135" rods or going to 6.385" rods. The short rod will need addtional crank clearance and create a less favorable rod ratio but the long rod requires the pin to ride behind the oil ring.

For a 5500 RPM street motor what is the best way to go?

Rods : Stock reconditioned GM 6.135" w/ ARP bolts - are these good enough? If going to a 6.385" rod, are I beam rods ok or do you need to go to H-beam rods.

Also, in an application such as this, a lot of the Stroker Kits use the KB Hypereutectic pistons. These can be installed with pressed in pins on the stock rods or floating pins. I would assume floating pins would be a must on the 6.385" rod combo. How do these hold up?

I have an Eagle 4.25 stroke crank and went with the 6.385 rod. It will be easier to balance the rotating assembly with the longer rod. What you may save in cost by using the 6.135 rod you will pay in adding heavy metal to balance the rotating assembly. The heavy metal they add for balancing is not cheap. Using the 6.385 rod should require little to no heavy metal.
As far as pistons I plan on using a j/e forged piston part# 142993 and they are not cheap about $550 this is a 454 bored 100 over plus the 4.25 crank (Internally balanced, uses same dampener and Flex plate / Fly wheel as a 396 / 427 ) equals 505 cu inches. People I have talked to have used the 6.135 rod and if they had to do it over again would have chose the 6.385 rod.

Yep,
I built mine with stock length rods, SRP pistons, and if doing it over it wouldhave 6.385 rods.

The pistons and crank cost the same, the difference in using a stock rod reconditioned and a aftermarket I-beam with capscrews, is only a couple of hundred dollars and part of this would be offset with the balancing.

Pretty much a wash and the longer rod is better.

Wouldnt the longer rod also be better bc it puts the pin higher in the piston making it less likely to rock and contact the cyl walls?

I've never been a fan of the pin sharing space with the oil ring.

Just for info, I have probably 20+ various big & small block street engines running around with the longer rods & pin under the oil ring with zero problems. 383's 400's 496's etc and again, no problems with the pin under the oil ring.
I have one 496 in a motor home that is run on propane with about 80,000 miles on it with a 6.385 rod. And they are floated pins.
Got another, same deal with 6.135 rods pressed pins, ext balance etc & it also has a bunch of miles on it with Fed Mog Hypers, no rail.
In my opinion the rail holding up the oil ring is not a problem.
Again in my opinion, it is one of those things that if enough people repeat it or write about it becomes gospel :D
Kinda like the longrod/short rod HP thing.

Mine's a standard length rod 496 and I would use the 1/4" longer rods now if I could do it over!!

I found out that the custom rods are now cheaper then cam-cutting the crank and adding the needed Heavi-Metal!!

pdq67

Mike, speaking of long rod/short rod.

Another option that has surfaced is boring my '72 block to 4.25 -4.28" {confirmed I will be able to do this without problem} using the readily available 454 stroker pistons {1.52 - 1.525 Comp Ht} with a 6.385 rod and my 3.76 crank to get a near zero deck 1.699 rod ratio 427 - 433 incher.

If I am right about this, it should make power like a Buick, only more because of the better heads. Everything about this feels correct. Better rod angle, much smoother piston acceleration/deceleration. Less stress on the pistons skirts and cylinder walls. Very economical to do. Should balance fine, the gain in rod wt should be close to the reduction in piston wt because of the shorter skirt.

Any thoughts on this?

I'll probably catch all kinds of flack for this but here's my opinion. :D
Rod length is one of the most over rated, over discussed parts of engine building.
I favor a rod long enough in strokers to be able to clear the needed counter weight as it normally makes balancing eaiser. If the rod is too short you can't get enough counterweight on the crank to balance it.
If you were to take the crank angles differences between say a 5.7 & 6" rod & overlaid them on a graph you probablly wouldn't be able to differentiate between the two lines on the graph!

In a longer rod engine the piston dwells longer around TDC & less around BDC which can be argued both ways.
If it is moving away from TDC slower it isn't putting as much power into turning the crank but it gives the charge more time to build pressure.

Ok, if it's a "short" rod it is moving away from TDC faster it will put more power into turning the crank sooner. :confused:
My basic opinion of rod length is if you don't have a good reason to change that actually makes sense,,,, leave it alone.

This was summed up real good at the Superflow Advanced Engine Technology Conference this year in a round table disscusion with some of the very best in the business of engine design in NASCAR.
This ain't a direct quote but it went something like this:
You decide on a stroke, design a piston to fit your needs, measure the deck height of the block & then make something to hook them together ;)
That was pretty much the consensus on the importance of rod length in overall engine design.

Makes total sense. It was my understanding that the longer rod should make a smoother running engine. Putting torque curve aside, is one better than the other for a smooth running engine.

I can't think of any reason it would. You will have a little less loading on the cylinder walls which I suppose could translate into less piston noise but if a little piston or tappet noise annoyed me I would probably find another hobby :D :D

Only my opinion but,, Ain't nothin sweeter than a properly adjusted solid roller humming along,,,,,,it just beats the hell out of being next to a ricer with a 1000 watt sound system playing "music" I can't even understand graemlins/angry.gif