I've heard from some places you can use emery cloth or coarse sandpaper and open up the small end of a production connecting rod +0.005 (or something like that) to accept floating pins instead of pressed pins. Obviously floaters will not work with unmodified GM rods. I have a perfect set of late model 1998 GM rods I want to use in a 350, but my pistons are floaters. I'd prefer floaters for ease of assembly. Only question is isn't there supposed to be some sort of bronze bushing or similar device in the small end or a rod set up for floating pins?

I know you can stress relieve stock rods in an oven and drill the small end of floater rods for more lube. What about this?

 

There is supposed to be a bushing. But, what you are talking about can be done. It works better if you use a brake cylinder hone and do it somewhat more accurately. But it will only last for a little while, maybe a couple thousand miles at the most, unless you feed it some oil; unfortunately, that's not easy. But if you can get access to a long enough drill bit in about the 3/32-1/8" range, you can drill a hole endwise through the rod; you'll need to drill a matching hole hole in the cap half of the rod bearing too. Somebody with laser drilling equipment could do it too.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

I've heard that you can either drill two hole in the top of the small end (how does sufficient oil get up there???) or one in the top of the small end and two at an angle underneath. So it comes down to oil...so in other words, is it altogether a bad idea, and if so, how much should I expect for this operation to be done? I definitely want this thing to last at least 80k miles or as much as a 400+HP 350 with forged pistons can.

So far the rods are magnafluxed, straightness checked, stress relieved, ARP bolts installed, and are almost ready for assembly. Haven't decided on pistons choice yet...

Wait, I see...are you saying I have to drill a hole up through the beam of the rod and the bearing into the small end so it gets a pressurized supply of oil? That sounds risky and sounds like it'll significantly weaken the rod...

[This message has been edited by dhirocz (edited August 23, 2001).]

 

Reamers also do an excellent job of fitting pins, but you have to make very small incremental passes to keep the surface smooth and clean.

------------------
Later,
Vader
------------------
"Get UP - Drop the bombshell!"
Adobe Acrobat Reader

[This message has been edited by Vader (edited August 23, 2001).]

 

It'll work OK. I'd drill the hole in the top. All the rods i have seen have the hole there as it weakens the rod the othere way. It should last a long time, you will wear the pins before the rods. Why not pay $40 or less to have them pressed on?



[This message has been edited by JoelOl75 (edited August 24, 2001).]

 

i'd never run a floating pin without the bronze bushing. as far as i know all floating pins can also be used as a pressed in pin with no problems.

------------------
ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

Problem is the machine shops around here are into customer wallet raping. They want $10 to mount each piston. I figured I could use floaters and not have to spend the extra $$$ since I have found several new sets of forged flat-tops fairly cheap. I never thought about using the floating pin as a pressed pin...makes sense now that I think about it...shame not to use a full floater when I can though.

So I can hone out the small end to fit a floating pin, and drill the top of the rod for lube(or into the small end from the big end), but without the bushing it can be risky as to how long the pin will last. I'm mostly worried about overheating the small end due to lack or lube and cracking it...in other words, I don't want it to break!

 

It'll work without the bushing. If you get the book "How to hotrod small block Chevys" it shows you how to drill (and chamfer) the hole in the top of the rod for proper lubrication of the wrist pin. It worked back then, so I guess it will still work today.

My only comment would be: this is precision machine work. This is NOT grabbing some sandpaper and having at it. Get a shop to do the work. You'll never get the wrist pin holes round or straight doing by hand or in your garage on the workbench. When all's said and done it will be more expensive to have the rods converted over than to press on a set of pistons. BUT YOU'LL NEVER HAVE TO WORRY ABOUT IT AGAIN! I did it on 2 of my engines so that I could swap pistons in my garage overnight without having to wait for the machine shop to open. I didn't give a hoot whether it made any more power or not- I wanted CONVENIENCE.

 

Also not all rods can be 'converted'... I've seen GMA and GMB code rods with the small end so thin the way it is, honing them to float isn't the best idea, and honing them even further for bushings would be impossible. GMK and GMX (Pink) seem to be the only choice.

That price is wayyyyy too high, find a different machine shop. I pay $33 and at most $40 seems to be the norm/avg for the whole set of 8

The brass bushings are a ford part, but I don't have the pn handy. Expect to pay more than a set of Summits all-ready bushed, sized, magnafluxed rods to have a machine shop do your rods, not including new bolts or sizing. Plus the summits have ARP bolts, so it's like getting them for free.

I'm running the Eagle SIR rods that are bushed, but this isn't a good idea because with these you will need to have the crank re-balanced, they are lighter than the stockers.