Connecting rod preparation
Thread Starter
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
Connecting rod and piston preparation
To get my forged Manley rod's to the same weight I should?? remove some material from some of them, # 6 #7 and #8
Rod's weight is (gram):
# Totaly..B-end...L-end
#1 591....431......160
#2 591....432......159
#3 591....432......159
#4 591....432......159
#5 592....432......160
#6 594....433......161
#7 596....435......161
#8 596....435......161
How important is it that all the rod's have exactly the same weight on both big end and little end?
I can't find any extra material to remove anywhere on the rod's, except where the arrows points.
It it safe to remove that material?
Rod's weight is (gram):
# Totaly..B-end...L-end
#1 591....431......160
#2 591....432......159
#3 591....432......159
#4 591....432......159
#5 592....432......160
#6 594....433......161
#7 596....435......161
#8 596....435......161
How important is it that all the rod's have exactly the same weight on both big end and little end?
I can't find any extra material to remove anywhere on the rod's, except where the arrows points.
It it safe to remove that material?
Last edited by gbak; Jan 17, 2007 at 02:53 AM.
Melting Slicks
Joined: Dec 2005
Posts: 2,441
Likes: 0
I wouldn't remove material from those rods, they don't have a dedicated balance pads to take material from. Instead I'd balance the entire rotating assembly as a unit.
Last edited by shafrs3; Jan 16, 2007 at 08:45 PM.
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
This is a job for a machinst. Many times, they'll juggle the rods around to get similar weights from crank pin to pin. They'll generally remove weight from the pads in the piston to balance small ends on rods with no balance pad. That rib you're pointing to is to help stiffen the cap, don't mess with it. Good luck!
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Unless you're gonna set a new land speed record or be in cup top-10 ... leave those rods alone & smile ... they're plenty close enough. Most manley's are very very close as yours are. It is quite possible the small differences you're seeing are weighing errors ... unless you're VERY VERY good at it and balance/fixture perfect ... and have done many repetitions & statistical analyses.
-edit- not llikely your machineshop will have the capability to match the bobweights within 5g anyway ... think of the 5g as a percentage of the bobweight (~1750g -1900g) ... it becomes rather insignificant.
-edit- not llikely your machineshop will have the capability to match the bobweights within 5g anyway ... think of the 5g as a percentage of the bobweight (~1750g -1900g) ... it becomes rather insignificant.
Last edited by jackson; Jan 6, 2007 at 09:35 AM.
Thread Starter
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
Unless you're gonna set a new land speed record or be in cup top-10 ... leave those rods alone & smile ... they're plenty close enough. Most manley's are very very close as yours are. It is quite possible the small differences you're seeing are weighing errors ...
not llikely your machineshop will have the capability to match the bobweights within 5g anyway ... think of the 5g as a percentage of the bobweight (~1750g -1900g) ... it becomes rather insignificant.
Been reading some book written by David Wizard and the recomendation was to get the rods to the same weight and as low as possible.
So you mean it isn't so important to weightmatch the rod's then?
Burning Brakes
Joined: Feb 2005
Posts: 894
Likes: 91
Manley Rods
Suggestion: DO NOT attempt to get those rods "even" unless you've got access to some "high-end" equipment. Simply "close your eyes" and install them, they will NOT pose a single issue with those variations. Believe me, we see this on 50% of the pieces coming in the door.
Under no circumstances remove that "stiffener" at the bottom of the cap!!! Not sure if anyone's aware out there but a "dollar" bill weighs a gram.
There's much more risk trying to get them the same.
Thanks, Gary in N.Y.
(Add) Jackson: we can get the bobweights down to 1/2 gram. Waste of valuable time however! Single gram or two is accurate enough and is fine for our field. On a side note here, technically speaking, you CANNOT balance a V-8 unit, you can simply make it "comfortable".
P.S. Other option is call, complain, and send them back! With all the CNC'ing going on you would think this would be uncommon. It's exactly what happens with much of the "off-shore" components. Even some of Manley's, maybe all now, are made overseas!
Under no circumstances remove that "stiffener" at the bottom of the cap!!! Not sure if anyone's aware out there but a "dollar" bill weighs a gram.
There's much more risk trying to get them the same.
Thanks, Gary in N.Y.
(Add) Jackson: we can get the bobweights down to 1/2 gram. Waste of valuable time however! Single gram or two is accurate enough and is fine for our field. On a side note here, technically speaking, you CANNOT balance a V-8 unit, you can simply make it "comfortable".
P.S. Other option is call, complain, and send them back! With all the CNC'ing going on you would think this would be uncommon. It's exactly what happens with much of the "off-shore" components. Even some of Manley's, maybe all now, are made overseas!
Last edited by GOSFAST; Jan 6, 2007 at 12:41 PM. Reason: Add Info
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
Is it more important to get the rod's small end and piston to the same weight, then to get the entire assembly to match?
And a dollar bill spinning 4000RPM in a 4inch circle weighs 454 grams, or 1 pound.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Thread Starter
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
I would get the big ends, revolving wt, the same.
Then balance the small end with pistons.
Then balance the small end with pistons.
Talking about balancing....
I have a old 7-1/4" Fluid Damper from the mid nineties, should I scrap it and buy a new one, or use it?
Depending who I talk to, I get two answers:
-Scrap it the silicone have hardened over the time, and does not act as it should.
-No problem it will lasts for years and years and....
BTW:
(I'm building a 383 with a int balanced crank)
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
I will discuss this with my machinist.
Talking about balancing....
I have a old 7-1/4" Fluid Damper from the mid nineties, should I scrap it and buy a new one, or use it?
Depending who I talk to, I get two answers:
-Scrap it the silicone have hardened over the time, and does not act as it should.
-No problem it will lasts for years and years and....
BTW:
(I'm building a 383 with a int balanced crank)
Talking about balancing....
I have a old 7-1/4" Fluid Damper from the mid nineties, should I scrap it and buy a new one, or use it?
Depending who I talk to, I get two answers:
-Scrap it the silicone have hardened over the time, and does not act as it should.
-No problem it will lasts for years and years and....
BTW:
(I'm building a 383 with a int balanced crank)
Thread Starter
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
I've talked to two different machinists now and both of them recommends me to remove some material from the more heavier rods.
I also talked to Manley and they recommended me not to remove any material from the cap rib.
Manley's recommendation was to grind a small radius on the outside edge on the cap.
I also talked to Manley and they recommended me not to remove any material from the cap rib.
Manley's recommendation was to grind a small radius on the outside edge on the cap.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
So very true!Moreover, many pro racers intentionally overbalance or underbalance ... to bring the point of harmonic imbalance outside operating rpm range / within a range the motor quickly passes through. Not so many pro racers here ... again, leave those rods alone.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
GoFast gave you correct info. I would never touch quality forged rods unless they have a cam clearance problem. My local race shop talks about doing .5 gram balancing jobs on race motors. They put the heaviest piston/pin with the lightest rods. I've also seen some trick piston skirts that holes bored in them to loose weight as well as this set of rods on a V-12 that had holes machined into the I beam and the lower part of the beam above the crank throw.
My latest 4 inch stroker crank has what is called pendulum cut throws to loose weight. It is a 40 pound class Callies in my 427
My latest 4 inch stroker crank has what is called pendulum cut throws to loose weight. It is a 40 pound class Callies in my 427
Thread Starter
Racer
Joined: Oct 2004
Posts: 285
Likes: 0
From: Stockholm
Ok! Got the message!
Next up is the rods little end and pistons.
If taking the heaviest piston with the lightest rod little end the differance between the reciprocating mass is 1,8 gr.
Is this good enough?
How important is it to radius the valve reliefs edge for getting less hot spots?
And do I need to shot peen the pistons top?
(As you might remember, I will use these pistons in with 11.2 comp.)
Next up is the rods little end and pistons.
If taking the heaviest piston with the lightest rod little end the differance between the reciprocating mass is 1,8 gr.
Is this good enough?
How important is it to radius the valve reliefs edge for getting less hot spots?
And do I need to shot peen the pistons top?
(As you might remember, I will use these pistons in with 11.2 comp.)
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
My 383 has 11.24 compression. Polishing piston tops is kind of a thing of the past. Now you just use the correct cam duration for the given fuel octane to prevent detonation.
Another fix for higher compression problems is thermal coatings for the piston tops. You can then run .5 - 1 point higher compression without pinging.
This is a picture of my ceramic coated 383 pistons.
Another fix for higher compression problems is thermal coatings for the piston tops. You can then run .5 - 1 point higher compression without pinging.
This is a picture of my ceramic coated 383 pistons.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
