Is connecting rod bushings needed?

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Darren

Darren

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hey guys my machine shop is getting ready to hang my KB pistons on my stock rods. He teels me he is going to inlarging the rod to accept the wrist pin and driil a hole for oiling the pin. So the pin will have no bushing. He said he has been doing it for years with no problems. the shop is well known in my area . the engine is a mild 383. what do you guys think. thanks
 
Yeah, it's really no big deal. Although I prefer a bushing, a lot of people run full floating without bushings without issue. I've done it myself.
 
thanks that makes me feel better.
 
Drilling the small hole in the top of the rod help oils the pinbetter also counter sink that hole a small amount have done this with both bushed an non bushed rods work very well
 
340demon said:
Drilling the small hole in the top of the rod help oils the pinbetter also counter sink that hole a small amount have done this with both bushed an non bushed rods work very well
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yes he said he was chamering the hole. allthough the pin clips coming free worry my a bit. they are the spring type.
 
Floating the pin right on the rod will be fine..it's been done many times before. If by spring type clips you mean Spiro-locs....(provided they're installed correctly)they ain't coming out of there!!
 
yes guys i ment spiro locks. i guess i can lube wrist pins myself before startup. they are building my a shortblock, so i can reach the pins from the bottom.
 
the 440 in my valiant was done like that.. don't think there was even a hole drilled and i never had a problem..
 
Darren said:
yes guys i ment spiro locks. i guess i can lube wrist pins myself before startup. they are building my a shortblock, so i can reach the pins from the bottom.
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Youre not lubing the pins.Bobs talking about where they float in the rods.
 
daredevil said:
Youre not lubing the pins.Bobs talking about where they float in the rods.
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i can most likley access the pin where it runs through the rod by injecting some assembly lube into the hole in the rod. if that makes sense. but i am sure the machine shop will have it pre lubed.
 
Are there any advantages/disadvantages to running the pins like this without the bushings?
I mean, I guess it takes bushing failure outta the equation, anything else?
 
It's usually "more acceptable" to run a softer metal like the bronze bushing against the steel wristpin. But that area really gets a ton of splash lube, so there's really not a thing wrong with running without the bushing. It's been argued both ways. I am surprised nobody's argued the case for bushings as much as people love to fight around here. Bottom line is, as long as it's getting oil, it'll be fine.
 
Something wrong with simply running the Pin with an "interference" in the Rod small end ? installed thermally ?

Yes, running the pin "floated" in the rod "steel on steel" has been done in the past, and was common back in the day.... but Old School & outdated today at best on TODAYS Oils.
and,
it NEVER WAS the best application of the "dissimilar hardness metals" under lubrication theory... due to the HARD tool steel Pin material against the 1053 steel Rod !
Too close in hardness IMO for todays NON Zinc and Moly/Phosphorous Oils !
Is this just a "brackets" type deal ?
or,
a Street driven application ?

If "Street"... IMO, you would be well advised to run the Pin with "Interference" in the Rod, and Pin-Fit the Pin Bores themselves to .001"on the 1.094" Pin, call it a day.
 
Challenger340 said:
Something wrong with simply running the Pin with an "interference" in the Rod small end ? installed thermally ?

Yes, running the pin "floated" in the rod "steel on steel" has been done in the past, and was common back in the day.... but Old School & outdated today at best on TODAYS Oils.
and,
it NEVER WAS the best application of the "dissimilar hardness metals" under lubrication theory... due to the HARD tool steel Pin material against the 1053 steel Rod !
Too close in hardness IMO for todays NON Zinc and Moly/Phosphorous Oils !
Is this just a "brackets" type deal ?
or,
a Street driven application ?

If "Street"... IMO, you would be well advised to run the Pin with "Interference" in the Rod, and Pin-Fit the Pin Bores themselves to .001"on the 1.094" Pin, call it a day.
Click to expand...

i respect your opinion and made some good points. but i have to ask. .. Have you ever had problems running floating pins with no bushings? the car is a 383 street car thanks
 
C130 Chief said:
Why not just run pressed pins?
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I agree. The floating pins really show no discernible advantage other than ease of assembly. It can be argued that floating pins eliminate some stress on the end of the rods and at the joint where the pin attaches the piston, but it is so minute, if at all the difference is not detectable.

Although, if you look back at all of the true HP factory engines, they did have floated wristpins. There was a reason there.
 
64 SRT8 Dart said:
Are there any advantages/disadvantages to running the pins like this without the bushings?
I mean, I guess it takes bushing failure outta the equation, anything else?
Click to expand...

when i had my 440 done for my valiant my machinist said the reason he wasn't using a bushing is that a lot of guys think the connecting rod gets too thin when opening it enough for the bushing.

my 440 was in my valiant and then in my demon. both were street cars first and logged quite a bit of street miles and i never had an issue.

these days old school still works but then again there are a ton of off the shelf parts for this stuff that is light years stronger and lighter than the old school stuff..
 
Darren said:
i respect your opinion and made some good points. but i have to ask. .. Have you ever had problems running floating pins with no bushings? the car is a 383 street car thanks
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I have not done it since the 70's ?
The reason is, there is no point.
What potential miniscule gain does anyone think full floating a Pin steel on steel will provide ?
The answer is absolutely NONE ! if there is ANY other option, which there is...
Simply Pin-Fit the Pin in the PISTON at .001", and run the Pin in the Rod at interference(pressed), good to go.

But yes, took lots apart for various reasons in those days that were steel on steel, still running, the Pins and Rod small end Bores were galled / fawked up.... requiring expensive decisions prior to re-assembly.

IMO, Doing it today, with TODAYS Oils, is pure folly.
But do whatever you want.
 
thanks for the good advise. my machinist recomended doing the floating pin way. thats how he prefers to do it. I am pretty sure the rods are already bored to accept the pins. So i hope it will be fine. thanks
 
Darren said:
thanks for the good advise. my machinist recomended doing the floating pin way. thats how he prefers to do it. I am pretty sure the rods are already bored to accept the pins. So i hope it will be fine. thanks
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The stock "ly" Rods only require a "light hone" to full-float, no "Boring"
maybe about 20-30 Minutes including Machine setup ?
VERY cheap to do THAT way ?
They are usually -.001" to -.002" interference stock, opening them up to .001" CLEARANCE to full float... so only .003" to Hone does not take very long.

No Offense, IMO
I just still think it's a BUNYAK way to do things, because I can see NO advantages, with only "potential" pitfalls ?

No matter, Good Luck with your build.
 
Challenger340 said:
No Offense, IMO
I just still think it's a BUNYAK way to do things, because I can see NO advantages, with only "potential" pitfalls ?
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You keep saying no advantage. Out of curiosity why did they make both pressed and floating to begin with?
 
I'd venture a guess that since you don't need heat and a press to install floating pins, you could say they facilitate ease of assembly.
 
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