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I have the rods that came out of the engine im rebuilding, can I reuse them on the new KB203-030 floating pin pistons, the old were press in, will it coast more to set them up for float? can I press the new piston pin on the old rod? what is resizing the rod? scat has a set for 260.00 , is float better then press? also, I already have the bearings so resizing would I have to get a new set of bearings?
I would imagine that after they were converted the rods to floating they would recondition the rods. They should be miked after they have been reconditiond
for bearing clearance. Yes full float is better, I think I would order the rods from scat.
Kurt
press work fine .realy no need to float your old rods . for street and mild race . i like press pin the rod is stronger and you do to have to worry about beating out the pin bushing or pin locks .part of hanging the piston s on your press in pin rods is to check the press on the pin 001.2 to 001.5 is what you need for press .and the big end gets resized if thats what you want i re build rods all the time .its up to you if you want your old rods re built its $10.00 a rod for the big end $5.00 a rod for check and tune in the pin end . i get $10.00 to bush the pin end a rod if you want so it addeds up fast then there rod bushing and rod bolts . this is my price hard to say whats your shops around you get or if they can do a good job . takes time to do rigth not many want to play with them .when you can buy new for under 300. you first re size the big end of the rod is this makes the rod shorter not by much .003 or so if you have a machine that will bore the small end you can move the pin center back were it needs to be as the bushing bore is bigger then the pin then you bore the bushing on the pin boring machine for the floating pin .the pin boring machine when set up will make all rods the same length
I was typing while Pat was posting. I'll let this ride anyway.....
Pressed pins are used in probably 99.9% of automotive engines because it's cheaper and quicker than floating pins. In a motor that will be put together and run for several seasons without coming apart, pressed pins are the way to go. If the motor is a race motor that will be coming apart for inspection on a regular basis, then floating pins might be more attractive.
Let's start with a primer. The bore on the small end of the rod on a pressed pin rod is bare steel. When the motor is being assembled, the rod is laid in a heating apparatus that heats the pin end, swelling the inside diameter of the bore to that a wrist pin can be pushed through the rod. As the rod cools, the bore gets smaller and locks the wrist pin to the rod, holding it in place laterally and circumferentially. The piston used with this arrangement can be machined for wrist pin locks, or it cannot be machined for wrist pin locks. It doesn't matter either way, because the wrist pin is locked to the rod and cannot move. If the piston is machined for locks, you simply don't use them.
The bore on the small end of the rod on a floating pin rod has been bored out to accept a thin-wall bronze bushing which is pressed into the pin end of the rod. The wrist pin rides on this bearing material and is free to rotate within the rod or move laterally within the rod. Therefore, you must use some means of keeping the wrist pin from moving laterally and riding on the cylinder wall where it could score the wall. This is where piston lock rings come into play. They keep the wrist pin from contacting the cylinder wall. Another way to keep the pin off the wall is to use Teflon wrist pin buttons that fit into the inside diameter of the wrist pin and stick out just far enough to ride on the cylinder wall, keeping the harder material of the wrist pin off the wall. The soft material won't score the wall, particularly while being bathed in engine oil that is splashed up off the crankshaft.
http://www.cbperformance.com/catalog.asp?ProductID=172
Resizing a rod is explained here....(taken from www.cdxetextbook.com)
Part 2: Step-by-step instruction
Remove piston pins
On these connecting rods the piston pins are semi-floating, which means they are free to move in the piston, but they are pinched into a permanent position in the small end of the rod.
To remove a pressed-in pin, the piston is set in a hydraulic press which forces the pin out of the grip of the small end of the rod.
Remove rod caps and bolts
With the rods separated, the caps now need to be removed. It is important that if you need to hit these to separate them, you only do this with a brass hammer.
Next, the old bolts are pushed out of the rod with the hydraulic press, and discarded.
Grind rod ends and caps
Each cap is kept with its rod and, one by one, their ends are very slightly reground in the same manner the main caps of the block were.
After the caps are done, the ends of the rods themselves are ground down a little as well. The grinding leaves a sharp edge that will have a tendency to scrape the backs of the rod bearings when they are installed, so the edges are smoothed with a file.
Install new rod bolts
Depending on the type of new rod bolts to be installed, the edge of the bolt hole may need to be chamfered to accept its shape.
Any metal shavings are cleaned out of the rods and caps and the bolt holes are cleared to prepare them for the new bolts.
Connecting rod bolts live deep in the motor and take a lot of abuse, so it is strongly recommended that - here in particular - you fit the highest quality bolts that you can get.
The threads are lubricated and the nuts installed and torqued on each rod. With brand new bolts the nuts are tightened and torqued and then loosened again and tightened and torqued again a total of three times. This will break in the bolt and make sure that the proper stretch is achieved for all of the bolts before the rod big ends are resized.
Realign connecting rod big ends
One by one each rod is honed to return the big end back to a perfect circle. The size is checked frequently during the process and when they are close to specification, they are left to cool for a while. Just as when the block was honed to realign it, the metal expands from the heat of the friction of the honing stones. Once cooled, the job is finished and the rods will all be within tolerance of the correct specification.
Larger machine shops might have a rod production machine. It can be set up to run off large numbers of rods in a short period of time. So, instead of waiting for your rods to be machined, sometimes it makes more sense to buy a whole set, with high quality new bolts already installed.
Thanks guys, I'm learning more from your input every day. Think I'll buy new rods, maybe I can sell the old ones, they still have the stock flattops hanging on them, the new ones come with ARP bolts, the new pistons do come with the spring clip retainer.One more thing , bout three weeks ago I stopped out at summit racing, I live 45mins. from them, very cool, like a hotrod part grocery store!
I put floating pin in all my old big block Dodges.
And over the years I never had one come apart or had any kind of problems with them.
But I did pull a couple motors apart with pressed pins in them that I could barley get the pistons to move by hand. I think there is just less friction with floating pins.
Just my opinion though. Kurt