Pressed vs. bushed connecting rod ends
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,912
Likes: 12
From: Schaumburg (Chicago) Illinois
Pressed vs. bushed connecting rod ends
RELATIVE TO MY LESS THAN 400 HP 383 BUILD. Is there any preference or REAL advantage of either pressed and bushed connecting rods.
Pro
Joined: Jun 2005
Posts: 540
Likes: 4
St. Jude Donor '09, '24
The bushed rods are a full floating design which lets the piston wrist pin turn in the rods end. The floating design is really for high revs which cuts down on the G forces on the wrist pin. If you aren't going to be turning high RPMs there wouldn't be much difference between the pressed rod and the full floating one IMHO, houstonvett
Racer
Joined: Mar 2006
Posts: 276
Likes: 1
From: Pistoia PT (ITALY)
Unless you will use Forged or Hypereutectics pistons...... no way to go with floating pins!
Anyway, for my opinion, due to the very good price of today's Hyp. Pistons there is no reason to stay with the cast ones...... so go with floating !
A very few horses..... but much more reliables.... keep in mind that a stroker SBC will have higher side loads at the pistons !
Anyway, for my opinion, due to the very good price of today's Hyp. Pistons there is no reason to stay with the cast ones...... so go with floating !
A very few horses..... but much more reliables.... keep in mind that a stroker SBC will have higher side loads at the pistons !
Melting Slicks
Joined: May 2002
Posts: 2,431
Likes: 52
From: Florida
I vote for forged pistons and floating wrist pins...you may add a power adder later (NOS). Floating pins also make for an easier rebuild. Hypers are a bit brittle IMO, better than cast, not as safe as forged.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Every engine I build for myself has forged pistons and full-floating piston pins. You'll get folks saying it is not needed for a mild street engine and they are right, plus it is expensive to go that way, but every little bit helps and I go for bulletproof every time on my stuff.
I'm partial to Venolia or Keith Black, depending on the application
Hans
I'm partial to Venolia or Keith Black, depending on the application
Hans
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
One part depends on the piston you decide to use cause they will have to have snap right grooves in them to retain the pin. (though there are teflon buttons also but only should be used in all out raceing) If your useing stock type rods it probaly will not be worth modifiying the rod for floating pins and if you do anyway don't go metal to metal have them bushed. There is "0" horse power in floating pins but they will spread the load wear out over a bigger surface.
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Le Mans Master
Joined: Apr 2005
Posts: 6,359
Likes: 428
From: Seattle Area WA
Most if not all pistons can be used with pressed rods. For a street car I vote the conservative pressed pin for dead on reliability. Yeah you can do double spiro locks etc, but if it's not being torn down on a regular basis why take the chance.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
There is no hp gains. The only advantage is disassembly.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
I have had several failures of floating pins used in street applications: The single bearing point at the pin bushing location will fail in a floating setup if the engine is exposed to any amount of detonation (not uncommon to occasionally occur with pump gas). For trouble-free and reliable street service, I only use pressed pins. 
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Hans
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Many pistons are dual-use ... But I've never seen a dual-use rod.
AFAIK ... you must float pins if rods are bushed.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Whether you know this or not, both the L88`s and Z`s 302`s have full floating pins. Do you still object to there use now?..
I better add the ZL1`s too before someone complains.,
You use Nylon buttons as pin locks, thats what I use on the race engines
I better add the ZL1`s too before someone complains.,
You use Nylon buttons as pin locks, thats what I use on the race engines
Last edited by Ironcross; Dec 6, 2007 at 12:24 AM.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
I should qualify this a little. All the previous post are correct. The main reason I do it is the RPM ranges my engines see. The BOSS is safe to 7900, the vair to 7200 and the 409 should handle 6800, which is a bunch with those heavy pistons. When I do the 427, I'll build it with the same intentions. A that point, floating pins are the way to go for me.
Hans
Hans
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
To install the pins, the small end of the rod is heated until the pins will slide in with no resistance, then allowed to cool to return the press fit. No stress at all.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa