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540-565 BBC Rod Length
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DRR Trophy
posted
I threw a rod in my 540 so I have to buy a new rotating assembly (block looks to be OK). I had a 6.385 rod in it but am debating if a 6.535 would be a better choice. The only thing I don't like with the idea of the longer rod is having the wrist pin higher in the piston and interfering with the ring lands. Thoughts?

This is a low deck block (9.800).
 
Posts: 20 | Location: MI | Registered: September 05, 2015Reply With QuoteReport This Post
DRR Pro
Picture of AlkyIROC
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Personally, short deck no, tall deck yes.

I run 6.385 rods in my 588 short deck. Wrist pin is in the oil control ring land and has no issues. Pushing to rod length an addition 0.150 may be acceptable but I think it moves it up too high into the ring land.

How many piston options are there for the longer rod?


www.hardtail.com Stephen's Racing Page
Best ET: 9.029
Best MPH: 150.45

 
Posts: 1352 | Location: Calgary | Registered: June 06, 2001Reply With QuoteReport This Post
DRR Trophy
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quote:
Originally posted by AlkyIROC:
Personally, short deck no, tall deck yes.

I run 6.385 rods in my 588 short deck. Wrist pin is in the oil control ring land and has no issues. Pushing to rod length an addition 0.150 may be acceptable but I think it moves it up too high into the ring land.

How many piston options are there for the longer rod?


Your combo has a longer stroke so it limits your options a little bit more. There arent as many piston options with the longer rod but I might end up going with a custom piston anyway depending on the bore size to get the one banged up cylinder cleaned up.
 
Posts: 20 | Location: MI | Registered: September 05, 2015Reply With QuoteReport This Post
DRR Top Comp
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The wrist pin up into the 3rd ring is well scienced out and not an issue. Most of the ring packs are the metric type now which are pretty thin/light and have no flutter problems like the "old" days. I would put a .400" long rod in it. But I've always been a fan of longer rods...
That would leave you with a relatively easy to find "off the shelf" compression distance of 1.120" piston..

Good luck with your project...


.
Dave



F J B

 
Posts: 4458 | Location: Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR Top Comp
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Lighter piston

Better ring seal
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Top Comp
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Yes, but it's usually offset by the extra weight of the longer rod..


.
Dave



F J B

 
Posts: 4458 | Location: Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR S/Pro
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I have been running a +.400 rod in a "semi" short deck (9.855) Dart Big "M" 582 for two years. Very happy with the results.

Bob
 
Posts: 3081 | Location: Lakeside, Ca | Registered: February 15, 2003Reply With QuoteReport This Post



DRR Sportsman
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We have 6.535” in our 540 and (2) 555s, all short decks. Larger rod to stroke ratio. Here’s an article from Oliver: https://oliverracingparts.com/...tandingRodRatios.pdf
 
Posts: 713 | Location: Upstate NY | Registered: July 02, 2013Reply With QuoteReport This Post
DRR S/Pro
Picture of Big Steve
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quote:
Originally posted by 183N:
We have 6.535” in our 540 and (2) 555s, all short decks. Larger rod to stroke ratio. Here’s an article from Oliver: https://oliverracingparts.com/...tandingRodRatios.pdf


Good read, thanks for posting
 
Posts: 2417 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post
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4.600 bore x 4.250 with a 7.000 Oliver rod

Screamer BBC


 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Sportsman
Picture of Mike Nitzsche
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Me being a non engine guy thinks that if your not interested in rotating the earth, go with the longest rod possible. My tall deck 540 with 6.700" rod was a revving beast and it's still going strong today very reliably.
 
Posts: 1364 | Location: Lansing,Mi | Registered: March 20, 2007Reply With QuoteReport This Post
DRR Top Comp
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I have a long rod and think it is better than a short one.

One of my SBC has 6.250 rods(454)and the other has 6.4. (408 Cu.In.)


https://postimg.cc/gallery/np3zpruo/
"Dunning-Kruger Effect"
-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue.

4X NE2 CHAMPION. 2020 TDRA NE2 Champion
 
Posts: 3999 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post
DRR Top Comp
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Rod ratio, man that's a flash from the past. I've always run long rods.

 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Elite
Picture of adv ET 266
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Stick with the +250. +400 is a huge compromise on piston and ring stack.



2005 2000lb 4 link dragster
home brew 582 BBC Dart 355
1.058
2.98
4.629@149
6.094
7.310@185

 
Posts: 12149 | Location: 33463 | Registered: February 04, 2004Reply With QuoteReport This Post



DRR S/Pro
Picture of SCDIV1
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Here is my experience

565 with +.400 rods
584 with +.400 rods
Both in a 9.800 deck block

The 565 was faster with the exact same cam, heads and intake and carb.

Some friends have had similar experiences comparing 565's to 582's....565 made equal or maybe even slightly more power than a 582

In my case I believe my heads/cam are the limiting factors and the added stroke magnified the issue.

One of my good racing friends is a big believer in the +.400 rods with the longer stroke is worse than a shorter rod with less stroke...

I don't accept that and just think every combo needs the right components to make the best power....

Engine builders learn from their experience what components work best......Trail and error....The dyno and the ET slip doesn't lie....

Longer rods comes from the ancient days of high revving Small Blocks......Longer rods reduce side thrust loads on the pistons.....

Big blocks have way lower rod to stroke ratios than old small blocks but generally aren't turning real high rpm's like SB's did....and they all pretty much work....
 
Posts: 2733 | Location: Where ever I am, I'm here and it's me | Registered: March 15, 2007Reply With QuoteReport This Post
DRR Elite
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Callies Ultra I beam #U15111 6.535 rod in my Firebird's engine



 
Posts: 13522 | Location: NJ | Registered: August 20, 2000Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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In the words of one of the best engine builders in pro stock history, and one of the winningest drivers as well, Warren Johnson:

Pick your ring package, pick your stroke, connect the two. Rod length isn't nearly as important as many make it out to be.


I run a 7" rod in my 665. 10.7" deck, 5" stroke....I could have fit a longer rod but I wanted the ring package I have and deck clearance.


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
 
Posts: 1465 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR Sportsman
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1.300 -1.325 @ 0 deck??? OR 10 in. Still stable for sure.
 
Posts: 1409 | Location: Under a Truck | Registered: August 23, 2013Reply With QuoteReport This Post
DRR Pro
Picture of Alaskaracer
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My ring pack is a 1.20", .020 below the deck


Mark Goulette
Owner/Driver of the Livin' The Dream Racing dragster
www.livinthedreamracing.com
"Speed kills but it's better than going slow!"
Authorized Amsoil Retailer
 
Posts: 1465 | Location: Back home in Alaska! | Registered: February 13, 2011Reply With QuoteReport This Post
DRR Trophy
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.250-.400-etc as said pick your stroke, pick you ring package, and connect the two. The WIN light in bracket racing does not care about rod length and I have run 6.135,6.385,6.535, as it may change the piston speed to cam events(very little) the win slip only cares about vehical reaction time and who crossed first with out breaking out. Any rod length can go .000 and dead on the dial so pick as needed and for longetivity.
 
Posts: 318 | Location: ohio | Registered: June 06, 2006Reply With QuoteReport This Post
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