[GoneNova/406]

i first ordered rods off ebay and then the pistons as i could afford it and some how ended up with press fit rods and floating pistons.i was looking forward to using the floating set up this time just for the ease of assembly and disassembly.i know i would have to pay to have the rods bushedto do this but the machine shop owner said the bushingis thin and comes lose quickly most times.i have a small library for sbc info and i didn't come across that info anywhere.are there any racers or machinist that can give me this info and the pro's and con's if any for using one or the other.i know most people use press for the street but i didn't find anything that said floaters should not be used except in racing.it actually said is just easier use the floaters and there was no down side.i'm simply talking about a 420-450h.p. street engine not an all out endurance racer.any info would be greatly appreciated.now that i am forced to deal with this problem i would just like to be well informed.thanks.
p.s.
since i don't have to pay anything extra for the press fit i am going that way but i still want the info.

 

[87442lover]

All you have to do is have the bushing drilled out a bit on those rods to make the wrist pin float in there. Then just drill a hole in the top for oil to get in.

 

[GoneNova/406]

yes i understand that but what the machine shop owner told me was that the bushing you use for it is very thin and losens up relatively soon.the rods i have are eagle sir 5.7 chevy rods.in the pictures i've been able to find of of both the press fit rod and the floater you can see that there is a bushing in the floater rod.none of the info i've found in print though says anything about the bushing being that thin or coming lose.

 

[k-star]

rods

There are bazillion rods out there with the bushing in them. There is no drama with the bushings unless the installer does not know what he is doing. You may want to look into a different shop. Maybe your guy does more on the stock line and you really need to be looking into someone with performance in mind.

You do realize that you can use the rods the way they are by just having the pistons installed onto them.

Keith

 

[[email protected]]

A pressed pin setup, when done correctly, gives better piston stability in the bore on a street engine.

If you want to run this setup as a full floater. Just have the shop hone the pressed pin rod to floater specs, then add an oil hole. NO BUSHING IS NEEDED! on a street motor. HeII, I've used steel rods with no bushings for plenty of Drag race motors. No problems.

 

[machine shop tom]

Yep, as Bob says, you can hone the rod ends to float the pins. Gm did it that way for years. You just have to drill and chamfer a hole in the very top of the rod to lubricate the pin.

K-star, I rebushed a set of Eagle H-Beam SBC rods last year. Two of the rods were O/S enough that the new bushing fell through. I ended up getting the guy 2 new rods (no help from Eagle, either). I had sold the rods to the guy 2 years earlier. The bushings (and wrist pins) were worn badly, but it was in a circle track 400 SBC.

tom

 

[k-star]

rods

Didn't gm do a secondary treatment to the pin bores on the rods that they floated?? I thought it was some kind of a hardining process??? I might be mistaken there.... I have taken some engines apart ( dirt stuff) that have no bushings in them (Pin to rod bore) and they really look bad. Maybe i just saw the worst case......

Tom,
I was thinking about all those ford 390 engines that had the factory bronze bushings in them.... I remember taking one apart that had like 200,000 miles on it and they looked like new. I replaced them but i am not sure why.....because the original ones were just fine... On those eagle rods were there special oversized bushings in them????

Keith

 

[[email protected]]

GM plated (copper-lead) the upper portion of the original run of 302 "Pink" rods. These were floating pin rods.

After the first production run they went to the pressed pin and only stated that they could be converted to floating by honing the bore diameter and adding a 1/16 hole (see early Chevrolet Hi-Perf Factory Book).

The situation also applied for the Big blocks. The Hi horsepower L-88 etc. got the plated floater rods.

 

[k-star]

ok

Thanks bob,,, That must be what i am remembering...

Keith

 

[GoneNova/406]

thanks guys.this place does alot of the stock car engines in the area.central ohio engine rebuilders.they sort of acted like i didn't need the floaters cause they are only for racing and they were looking out for me or something.give me the info and let me choose.i can handle it.you guys are right though i think i'll find another shop to use.these guys were just really handy because of location to me.anyway thanks,i'll keep this info for next time.

 

[GoneNova/406]

i have a small chevy info library and spent several days there and online looking for this info and now i feel like a jack-*** because it was in one of the chevy parts interchange mauals that i looked in and didn't see it before.all of it is there though and i think i am going to take it with me to the machine shop and ask them whats up.again thanks everyone for your input,you were all right.

 

[406 ss monte]

i had a builder tell me that a floating rod engine would make a little more power because after the pistons ge hot, they swell on the wrist pin putting pressure on it creating resistance, & a floating rode just gave it another pivot point to help loosen it up. maybe he's full of sh$t. i don't know. can any one confirm this?

 

[machine shop tom]

He seems like he would be the type to iron is underwear and mark his socks left and right.

tom

 

[k-star]

He seems like he would be the type to iron is underwear and mark his socks left and right.

tom

That's funny,,, I don't care who you are..... Git er done!!!!!

 

[machine shop tom]

That's funny,,, I don't care who you are..... Git er done!!!!!

Here's yer sign.....

 

[Triaged]

i had a builder tell me that a floating rod engine would make a little more power because after the pistons ge hot, they swell on the wrist pin putting pressure on it creating resistance, & a floating rode just gave it another pivot point to help loosen it up. maybe he's full of sh$t. i don't know. can any one confirm this?

Holes get BIGGER when the part heats up. The piston will expand more then the pin because alumimum has a higher coefficient of thermal expansion than steel and the piston will be hotter then the pin.