Bushing six pack rods for 1.094 pins

[polyjohn]

Some very good points there Guys.
A number matching 1971 GTX is what I have and it will stay 'as is'.

If I am going to run into the 10's with my 512ci engine then its going to be a stripped out race-car then?
Where is the cut-off between a number matching street-stripper and a drag car?

The MMA-UK say its 21.01 in their book but have insisted on cages at 13.99 as well.
Safety is the first precaution of the MMA and self harming on the drag strip is frowned upon indeed.

Happy new Year to all who have contributed to my thread.
Its sad some prefer Chinese rods over factory six-pack, but hey, thats progress ( I suppose)?
Its a shame that ARP wasted their time making 3/8 rod bolts for many years, as no one rates them.

 

[polyjohn]

Talking of rods and bolts and all things 426 engine.
How's about a hemi rod, good or bad?

(The six-pack rod is almost identical to the hemi rod except for the bolts.)
So Weslake Engineering got Mother Mopar to make some hemi/440 length rods in 1969.

The front rod is outta my 426 hemi.(6.860)
The rod on the piston is outta the Weslake 426 Nascar engine. (6.768)

Back then they didn't have any options and they still ran over 200mph with them.
The weirdest thing is they are factory press fit how bizarre indeed.
I guess the six-pack rod had not been invented in 1969, so they made a special hemi 440/426 rod!?

 

[padam]

There are a lot of DNF’s for mopars in those old NASCAR programs.

 

[33 IMP]

Talking of rods and bolts and all things 426 engine.
How's about a hemi rod, good or bad?

(The six-pack rod is almost identical to the hemi rod except for the bolts.)
So Weslake Engineering got Mother Mopar to make some hemi/440 length rods in 1969.

The front rod is outta my 426 hemi.(6.860)
The rod on the piston is outta the Weslake 426 Nascar engine. (6.768)

Back then they didn't have any options and they still ran over 200mph with them.
The weirdest thing is they are factory press fit how bizarre indeed.
I guess the six-pack rod had not been invented in 1969!?

View attachment 1780540

You are correct. The 69 Sixpack motors used LY rods. Not till 1970 did the Sixpack engines get Sixpack rods.
And .100 longer rod is hardly the same except for bolts.
And I'm pretty sure the Nascar engines used Carillo rods even way back then......

 

[polyjohn]

Both rods in the picture are Hemi rods!

The front one is a longer hemi rod.
The one attached to the piston is also a Hemi rod, special made at 440/426 length for Weslake Engineering in 1969.

Both have factory 7/16 rod bolts and are the same apart from one is .100 shorter for a wedge engine.

I guess you are saying ''they is all 50+ years old and are scrap''...
Best I get some Molnars and put this thread to bed for 2024...

 

[Curiousyellow71]

We run Ly rods in a couple cars yet. Years ago we had a 70 six pack engine that spun a bearing, but the HD Rod held together and it lived to fight another day.

We raced Ly rods with the 2295 Trw/federal mogul pistons for years. Those pistons had a special tapered wrist pin that may have helped the longevity w its pressed fit pins. At one time we checked the tach recall and it had seen 8300 rpm. In the mid 10s we we were going out the traps over 7k. The rods held in there till a cylinder wall gave up. When that happened it broke a rod bolt. I am not sure if it would have mattered what Rods were in it at that point. We have had a couple sets of rods Bushed over the years. The machine shop usually measures the needed specs and orders them. They typically are not specific to a engine, they are just bushings and are less then half price of what you would typically spend. If this were my car I would likely keep the six pack Rods in it as well. They are pretty stout. Yes, there lots of rods available that are better, buy I get what the op is trying to do.

 

[RemCharger]

We run Ly rods in a couple cars yet. Had a 70 six pack engine that spun a bearing, but the HD Rod held together. We ran Ly rods with the heavy 2295 Trw/federal mogul pistons for years. Those pistons had a special tapered wrist pin that may have helped the longevity w its pressed fit pistons. At one time we checked the tach recall and it had seen 8300 rpm. In the mid 10s we we were going out the traps over 7k. The rods held in there till a cylinder wall gave up. When that happened it broke a rod bolt. I am not sure of it would have mattered what Rods were in it at that point. We have had a couple sets of rods Bushed over the years. The machine shop usually measures the needed specs and orderd them. They typically are not specific to a engine, they are just bushings and are less then half price of what you would typically spend. If this were my car I would likely keep the six pack Rods in it as well. They are pretty stout. Yes, there lots of rods available that are better, buy I get what the op is trying to do.

On the motor that the cylinder was toast, were the pins bushed?

 

[Curiousyellow71]

On the motor that the cylinder was toast, were the pins bushed?

Nope...press fit.
It had wrist pins in it that were factory machined to be stronger. Guessing that may have helped? Dunno.

That block got 2 sleeves and is still going. I wouldn't push a LY rod or a six pack rod as hard as we did back then. LOL

 

[RemCharger]

Nope...press fit.
It had wrist pins in it that were factory machined to be stronger. Guessing that may have helped? Dunno.

That block got 2 sleeves and is still going. I wouldn't push a LY rod or a six pack Rods as hard as we did back then. LOL

Just asking because the only time I broke a rod was from the pin going out into the cylinder, and locking it up in the groove and taking out the adjacent rod. So not a rod failure, but pin failure creating a rod failure

 

[Moparfever65]

Only time I threw a rod was street racing my 69 Cougar, 351W, stock rods. Don't know what RPM, but I didn't want to lose. Found the rod nut stripped and the cap broke, crank came around and pushed the rod through the pan. ARP bolts ever since.

 

[Gunner1]

Seems like most, if not all, aftermarket rods are Chinese. All i-beam aftermarket rods I've seen are 5140 Chinese. Why 5140 i don't know. Apparently cheaper than 4340. I've read were 5140 is used a lot in ship building. For what I do 5140 is good enough or maybe better than factory steel. Keep in mind that back in that era cast rods were still being used by some manufacturers. I think i- beam versus h- beam might be a good discussion.

If I remember correctly all of Scat’s H Beams are 4340. The owner would periodically take a sample rod and crank and cut them up. He would send the pieces to a lab for a metallurgy report.

 

[polyjohn]

I suppose I am 'living in the past' with my GTX and its numbers matching engine.
I know the sixpack set up was a fine example of Mopar engineering (at that time).

Never broke a rod in forty years of drag racing.
Used everything from LY to BME aluminium.

We use what parts we want too and until it breaks we just carry on regardless.
Happy New Year to one and All.

 

[PsyOps]

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.
They didn't scuff the pins and the only failure we found was bigend bearings starting to pick-up.

So we are now taking them down to below LY rod weights, but no where near modern rods.
Plus we want to have nice bronze bush to aid the small end.

Happy Christmas to all the Mopar folks who still love their old Mopars.

So, just curious, what kind of metal has to come out of the crank when you lighten the Six Pac rods to below LY rods weight? Also, please excuse me if I missed it, what pistons are you using? Are they factory slugs? Thanks and Mopar to ya!

 

[polyjohn]

Hello PsyOps,

At last in 2025 a sensible question.
Factory slugs are cast six-pack pistons.

The new replacements are Indian Speed Pro, forged.
How good they are is yet to be discovered?

They are no heavier than the factory High compression cast piston.
I could lighten them but reciprocating weight is only half as bad as Rotational weight.

Taking as much weight as possible out of the BIG END has much more effect on the crank counterweights.
Once you get this weight down you can use any pre 1970 steel crankshafts instead of just the 1970 - 1974 six-pack cranks.

But I prefer the later cranks as they have a wider end thrust surface and wider bearings too.
This means you would have to use a 1972 block onwards to get them to fit.

I have modified the later bearings on a lathe to fit into the earlier blocks.
My 1969 four speed Charger wrecked the crank bearing end thrust so I am wary of pre 70 cranks.

 

[polyjohn]

There is an assumption that I do not know anything about rods and crankshafts?
I have worked in a specialist V8 machine shop for 25 years!

I can bore blocks, deck blocks, regrind crankshafts and balance them as well.
Rod prep has been my go to subject for 25 years.

All I asked for was thoughts on small end bearings.
Anyone can buy a set of expensive rods, as we all have.

Most folks will just buy a balanced (stroker) kit from 440 Source or Hughes etc.
Some of us want to just make our Mopars slightly better than before.

The 440 wasn't seen as a performance engine and Mopar was cutting costs.
All the early small-block rods are bushed but no LY or six-pack rod to my knowledge.

Most development went into the hemi engine and the 383 and 440 was left out.
As I said before , we have run six-pack rods down to 10.20 in a B-body.

I'm sure I will be OK with 12.01 lol.
Happy New Year to all six-pack lovers like me...

 

[Curiousyellow71]

There is an assumption that I do not know anything about rods and crankshafts?
I have worked in a specialist V8 machine shop for 25 years!

I can bore blocks, deck blocks, regrind crankshafts and balance them as well.
Rod prep has been my go to subject for 25 years.

All I asked for was thoughts on small end bearings.
Anyone can buy a set of expensive rods, as we all have.

Most folks will just buy a balanced (stroker) kit from 440 Source or Hughes etc.
Some of us want to just make our Mopars slightly better than before.

The 440 wasn't seen as a performance engine and Mopar was cutting costs.
All the early small-block rods are bushed but no LY or six-pack.

Most development went into the hemi engine and the 383 and 440 was left out.
As I said before , we have run six-pack rods down to 10.20 in a B-body.

I'm sure I will be OK with 12.01 lol.
Happy New Year to all six-pack lovers like me...

View attachment 1782179

Every 2355 six pack piston I have seen doesn't have the groove or for a retainer/snap ring for a full floating rod? Yes, you can cut them in w a lathe. Do you have to run those pistons?

There are several companies that make rod bushings for a 1.094 pin. B1094 is a part number that you see quite often. I wish I could remember the brand of bushing we've been using. Maybe I will come up w it later.Lol

 

[lewtot184]

There is an assumption that I do not know anything about rods and crankshafts?
I have worked in a specialist V8 machine shop for 25 years!

I can bore blocks, deck blocks, regrind crankshafts and balance them as well.
Rod prep has been my go to subject for 25 years.

All I asked for was thoughts on small end bearings.
Anyone can buy a set of expensive rods, as we all have.

Most folks will just buy a balanced (stroker) kit from 440 Source or Hughes etc.
Some of us want to just make our Mopars slightly better than before.

The 440 wasn't seen as a performance engine and Mopar was cutting costs.
All the early small-block rods are bushed but no LY or six-pack.

Most development went into the hemi engine and the 383 and 440 was left out.
As I said before , we have run six-pack rods down to 10.20 in a B-body.

I'm sure I will be OK with 12.01 lol.
Happy New Year to all six-pack lovers like me...

View attachment 1782179

Interesting. My thoughts about the wedges are that Chrysler basically quit on upgrades after the early 1964 super stock cars in favor of the hemi's. The 6paks had some upgrades but nothing like the hemi engine. Chrysler never had the money Ford or GM had. They always tried to make something out of the parts bin for street performance.

 

[polyjohn]

Well done Curious Yellow guy!

You are the first person to mention that the Speed pro piston does not have pin retainer clip grooves!
In my old age, I mixed up my Pro-Tru with my Speed-Pro how foolish of me...

It took four pages before someone actually noticed my schoolboy error...

 

[Curiousyellow71]

Well done Curious Yellow guy!

You are the first person to mention that the Speed pro piston does not have pin retainer clip grooves!
In my old age, I mixed up my Pro-Tru with my Speed-Pro how foolish of me...

It took four pages before someone actually noticed my schoolboy error...

View attachment 1782309

That makes more sense. The Wiseco's are a nice light weight piston with narrow rings and I believe made in Ohio? Speedpro like you said.. is made in India. The wiseco's 2.05 is a odd compression height, but that doesn't really matter on a open chamber head if it gets you the compression your after. We have a .040 over 440 with them hung on Ly rods. We had to lighten the crank a bunch to balance it. Our block is decked quite a bit from running 2295 pistons in its previous race life. It makes sense that installing a light weight piston will help the block survive.. and the factory rods! We almost ran six pack/hd rods on our wiseco's, we had the rods. Got talked out of it.Lol