Bushing six pack rods for 1.094 pins

[RemCharger]

Great replies guys!

Yes its a 1971 440 GTX (matching numbers) engine which will be as original as possible.
How fast can you go with a six-pack rod?

We ran them down to 10.20 without fully lightening them and just honed out for full floating pin.

For those that have glossed over the OPs vital information.

 

[polyjohn]

I think you are missing the point with some of the replies Guys!
Its a 1971 HP engine with six-pack rods from the factory.

I will be running in a Superstock class and it will be as Mother Mopar made it in 1971.
We have run six-pack rods down to 10.20 in a street legal B-body so we know they is OK.

Lightening is part of the cleaning up process when you clean the beams and remove excess end weight.
We can get them down to 600g BE and 250g SE without going mad.

I have some that are even down at 580g BE and 230g SE and still are happy that no strength has been changed.
By polishing the beams after removing the foundry forging burrs the rods are actually stronger now!

You can see from this set the SE weights are very different, some tall some short.
We pick a set that has all tall SE weights and then that's around 40grams can be removed (far right rod).

Most six-pack rods have around 50grams to removed from the bottom weight (10g from beam) so added up around 100grams in total.
I'm hoping that one day (in my Duster) I will run a factory all iron 440ci into the Nines...
Best so far is 10.40 N/A and 10.20 with 150 shot of NOS.

 

[PRHeads]

Yes its a 1971 440 GTX (matching numbers) engine which will be as original as possible.

Well…….. except for the bushed rods (that wouldn’t have been in there as it rolled off the assy line).

 

[1KoolBee]

H Beams are a “Cheap” insurance policy. Put the 6-pack rods in a display case, unless your 440 is never going to see 5500+!

 

[BSB67]

Well…….. except for the bushed rods (that wouldn’t have been in there as it rolled off the assy line).

And that was kinda my question. Exactly where is the line for being factory stuff, and is it a rule thing, or self imposed?

 

[polyjohn]

6500rpm all day long with factory rods...
Factory is factory, once you change the rods then you start changing everything.

Pistons, crankshaft, camshaft, solid lifters, heads, it is endless.
Self imposed factory is factory apart from Indian sixpack forged pistons.

Back in 1971 they was running 11.50 with factory blueprinted 440's!
Oh I forgot to say its 12.01 (or its a full cage) so that's my self imposed limit too.

If you look at my avatar its a 511ci motor that I could use, but its not factory lol.
Here's a closeup with Edelbrocks but still a street engine with a .550 crower roller.

It would run a Ten quite easily but then its all the safety gear you need and that's expensive too.

 

[padam]

6500rpm all day long with factory rods...
Factory is factory, once you change the rods then you start changing everything.

Pistons, crankshaft, camshaft, solid lifters, heads, it is endless.
Self imposed factory is factory apart from Indian sixpack forged pistons.

Back in 1971 they was running 11.50 with factory blueprinted 440's!
Oh I forgot to say its 12.01 (or its a full cage) so that's my self imposed limit too.

If you look at my avatar its a 511ci motor that I could use, but its not factory lol.
Here's a closeup with Edelbrocks but still a street engine with a .550 crower roller.

It would run a Ten quite easily but then its all the safety gear you need and that's expensive too.
View attachment 1779060

Expensive and also the downside of possibly keeping you alive.

 

[RemCharger]

6500rpm all day long with factory rods...
Factory is factory, once you change the rods then you start changing everything.

Pistons, crankshaft, camshaft, solid lifters, heads, it is endless.
Self imposed factory is factory apart from Indian sixpack forged pistons.

Back in 1971 they was running 11.50 with factory blueprinted 440's!
Oh I forgot to say its 12.01 (or its a full cage) so that's my self imposed limit too.

If you look at my avatar its a 511ci motor that I could use, but its not factory lol.
Here's a closeup with Edelbrocks but still a street engine with a .550 crower roller.

It would run a Ten quite easily but then its all the safety gear you need and that's expensive too.
View attachment 1779060

You just bought this polara today? ( FCBO)

 

[Cranky]

5500 lol....people were running 440's well above that when 'mom' decided to try and stop the warranty work by adding the 6 pack rod to the 440 equipped cars but all they did was make things worse by not installing at least a high strength rod bolt on the 'new' rods. In the very early 80's I helped a buddy run a 4 speed roadrunner that had 6 pack rods with HS bolts, polished beams etc but with TRW 2295 forged pistons. Not a very light piston but the rods stayed in it even shifting it in the high 6k range. Never had any issues with them but broke just about everything else lol

 

[RemCharger]

To be honest, IMO, the primary failure point is the lack of floating pins in a high- rpm deal. Not the rod, not the bolts, not the piston. Seized pins will create those issues.

 

[Cranky]

To be honest, IMO, the primary failure point is the lack of floating pins in a high- rpm deal. Not the rod, not the bolts, not the piston. Seized pins will create those issues.View attachment 1779155

Stock rod bolts are not all that good with heavy pistons and yeah, I'm going to float the pins in any engine that's going to see over 6k but I'm betting there's been plenty that took their engines over 6 with pressed pins.

 

[RemCharger]

Stock rod bolts are not all that good with heavy pistons and yeah, I'm going to float the pins in any engine that's going to see over 6k but I'm betting there's been plenty that took their engines over 6 with pressed pins.

I'm on board with that. We have a 6500 rpm 383 that's doing just fine so far. 5 years and counting racing everyday the tracks open.
It's the 7- 7200 engines that the pressed pins will kill ya. That's why in post #15 I was looking for bushings. 1.09 h beam rods weren't easy to find in a B rod.

 

[1KoolBee]

5500 lol....people were running 440's well above that when 'mom' decided to try and stop the warranty work by adding the 6 pack rod to the 440 equipped cars but all they did was make things worse by not installing at least a high strength rod bolt on the 'new' rods. In the very early 80's I helped a buddy run a 4 speed roadrunner that had 6 pack rods with HS bolts, polished beams etc but with TRW 2295 forged pistons. Not a very light piston but the rods stayed in it even shifting it in the high 6k range. Never had any issues with them but broke just about everything else lol

Ya back when nobody cared about a “numbers matching “ block

 

[PRHeads]

Back when affordable aftermarket rods for Mopars weren’t very common………..which was back when I spent most of my fair weather weekends at the track.
Near the end of the season, when the stuff was getting used up, and the air was getting good……… it wasn’t too unusual to see someone blow up a 440.
When it was a “rod failure”, it was usually where the rod was simply broken about mid-way up the beam.
Sometimes the big end still attached to the crank, and not burned up or having spun a bearing.
Straight up rod failure.

I even had it happen to one of my customers that we reworked the rods for. Bushed to .990, custom JE pistons that were waaaay lighter than factory type parts.

Granted, these failures were usually just LY rods.

The next build got Eagles……. No more broken rods.

 

[PROSTOCKTOM]

OEM rods are made from 5140 material. Sure you can go in and lighten them, but the material is not nears as strong as 4340, so you are actually weakening them by doing so.

Plus the aftermarket rods have a 7/16" bolt over the OEM, but they are also a cap screw design which is superior, and doweled.

For what it cost to build an engine today using old OEM rods is like riding around with the pin pulled out of a grenade. The $720 investment in new rods is cheap insurance.

Tom

 

[1KoolBee]

I'm on board with that. We have a 6500 rpm 383 that's doing just fine so far. 5 years and counting racing everyday the tracks open.
It's the 7- 7200 engines that the pressed pins will kill ya. That's why in post #15 I was looking for bushings. 1.09 h beam rods weren't easy to find in a B rod.

383 is a much different story, it will literally rpm limit via valve float before the rods give up due to the small-block sized stroke and big block bore.

I did a lot sadistic abuse to my 68 Bee’s 383 back in the day. Bored it .030/rebuilt in ‘76 at 77k miles and I tore it down again in ‘97 at 130k miles. It came from the factory with an mis-machined rod bolt seat on one rod that was just starting to crack down into the bolt hole. Caught it just in time. Replaced rod, did a ring and valve, rods resized, shot peened, balanced, new rod bolts, bearings, bigger cam, she’s still running great today.

 

[1KoolBee]

OEM rods are made from 5140 material. Sure you can go in and lighten them, but the material is not nears as strong as 4340, so you are actually weakening them by doing so.

Plus the aftermarket rods have a 7/16" bolt over the OEM, but they are also a cap screw design which is superior, and doweled.

For what it cost to build an engine today using old OEM rods is like riding around with the pin pulled out of a grenade. The $720 investment in new rods is cheap insurance.

Tom

I couldn’t agree with you more Tom!

 

[PROSTOCKTOM]

For what it's worth 95 percent of the issues I see with 50 year old rods is the beams breaking right above the big end.

I guess it a combination of material strength and to many cycles of use over a long period of time. The OEM components were never designed for the uses of today's output.

Tom

 

[Diodedog]

To be honest, IMO, the primary failure point is the lack of floating pins in a high- rpm deal. Not the rod, not the bolts, not the piston. Seized pins will create those issues.View attachment 1779155

I hone the piston pin bores to give 12-13 tenths clearance in a pressed pin situation, it's a lot better than the 5-6 tenths they come with, that said the Molnar rods are the best deal out there for a great set of rods.

 

[Geoff 2]

Not only is the stock 3/8" bolt weaker.........but the scallop in the rod shoulder to accomodate the head of the bolt also weakens the rod. Both weak points eliminated with H beam rods....