Mopar 383 Connecting Rods
 

What brand of connecting rods are guys using in Stock and SS 383 Mopar engines? The only ones currently available that are NHRA legal are the Eagle (at the low end) and Carrillo rods (at the high end). The C-A and the Hale rods seem to be non-existent at this point. My engine guy went through 60 stock rods to find eight that would stay round on the big end.

Re: Mopar 383 Connecting Rods
 

If you're running stock the stock rods are fine. Unless they're really messed up and been beat to death the only way you'll break one is to spin a bearing and not lift.

Re: Mopar 383 Connecting Rods
 

James I would like to know the criteria for the rod selection. I have a problem keeping the big end round on my stuff. Fixing them shortens the rods and requires block to be decked to keep compression up.
Thanks

Re: Mopar 383 Connecting Rods
 

Larry, my engine guy is an old tool and die machinist and ran a MP Colt back in the late 1970s and early 1980s. He worked at the Dodge NASCAR engine program with Arrington and Ted Flack when Dodge got back into NASCAR. His rod methodology is to torque the rod bolts, measure the roundness on his Sunnen rod hone dial bore gauge. He redid a set of Manley Hemi Pro I-beam rods that I bought from Mike Bogina. Mike had them on the shelf, brand new in the box. Apparently Manley did not use enough assembly lube when they torqued the rod bolts and there was galling on the threads and under the bolt heads. Robert resized the big ends with new rod bolts, dowels, ground the caps and big end and resized the big ends to under ,0001" (nearly zero). The next day they must have stress relieved to be .0001" out of round.

On the stock rods, he measures the out of round, un-torques the bolts, and retorques them. If they don't repeat they end up in the junk pile. Apparently the stock 383 rods are weak, maybe a low alloy steel or medium carbon steel like AISI 1053. He was building a 383 for a guys pickup and they got a set of Jim Hales (Manley) rods, but they needed work as they were used. Overkill for the pickup build for sure.

Re: Mopar 383 Connecting Rods
 

If we resize rods we offset bush the rods small side to keep length.
Nothing wrong with stock rod but by time you rework them they are
about the same money as Eagles

Re: Mopar 383 Connecting Rods
 

If it was me, for .0001 I'd dig those 60 stock forgings out of that junk pile.

Re: Mopar 383 Connecting Rods
 

I assume he is checking those rods with the stock bolts. I have at least 10 sets of stock 383 rods laying around, when I get the time I'll try the torquing and retorquing to check how consistent they are.

Re: Mopar 383 Connecting Rods
 

Dave, it was my Manley Hemi Pro-I Beam rods that went .0001" out of round after resizing. The big end spec on the Mopar BB rods are 2.5000" to 2.5005" per the Clevite book. I'm assuming that the 383 rods wouldn't repeat within the ,0005" range. I'm sure that was with the stock 383 bolts. I wasn't around when he went through the rod testing on the 383 rods, so I don't know the exact procedure done.

My engine guy also does hardness testing on the rods. I bought a set of Manley 440 Sportsman rods and they were in the HRC 26-29 range. It appears to me that is the normalized hardness for 4340 steel. The hardness on the Hemi I-beams were in the 31.5-39 HRC range (corresponding to 130 ksi to 159ksi yield strength per the EMJ Blue Book charts). Maybe Manley saves money on the Sportsman rods by skipping the heat treatment and final sizing after heat treat steps?

Re: Mopar 383 Connecting Rods
 

Is your machinist using an AG300 to check size? If so how does he check for straightness of the bore. To check for hourglass or barrel shaped bores.
Thanks

GTX John
How thin, wall thickness, can the pin bore wall be and still live after bushing the pin bore? Does the bushing get burnished or is it a shrink fit?
Thanks

Re: Mopar 383 Connecting Rods
 

Larry, I don't really know for sure. I saw him put them on the gauge, but I didn't pay attention to the details how he used it close enough. Next time I head to Florida, I'll take my Mitutoyo 2" ring gauge along and have him show me how he does it. Here is a link the Sunnen instructions from the Goodson webpage.

https://cdn.shopify.com/s/files/1/14...cisionGage.pdf

Re: Mopar 383 Connecting Rods
 

It looks like mine

Re: Mopar 383 Connecting Rods
 

Larry, that looks like the AG 300 I learned on. We were taught to check the bore against the faceplate, then pull the rod away while holding it steady against the fixed upper point, then gently rock the rod. We would do that at a couple of points, flip the rod over and check the other side. That would allow us to check for barrel or taper. Sunnen used to lease a PG series gauge with a faceplate that slid in and out to check taper or barrel. Even if I could afford one, it would be probably be to finicky for my little un-airconditioned shop.

Re: Mopar 383 Connecting Rods
 

Back to the original post. It's difficult to qualify OEM mass production rods. Small variations in bolt centerline between the rod and cap, how perpendicular the bolt (or nut) spotface is to the bolt centerline affect the repeatability when the bolt is torqued.

Back in the Buick days we would deburr a small spot inside the "H" beam of a Carrillo rod, just above the bolt thread exit. It's been too long to recall the specifics, but I remember it was significant enough to resize the big end. That's when I began to understand how touchy rods can be, and how important it is to maintain consistency between preparation and assembly.

The shop procedure was to hone the big ends individually since the rods run on split journals. It required a lot of attention to keep the stones and guide shoes from wearing in a fashion that caused barrel shaped housing bores.

Re: Mopar 383 Connecting Rods
 

I did most every rod in a small shop for over 10 years.

All brands and from street rebuilds to race engines of all kinds.

Sunnen manual LBB machine with the gauge.

Did big ends, small ends, bushed rods, offset bushed and reduced pin sizes using bushings we made or bought.

Stock rods used in race engines were generally out of round once run....

Usually a good amount....

We used SPS bolts back then and picked the best looking cores we could find.....Did not matter once it was run....out of round...

Mag, shotpeen, resize, bush pin end....generally

Very difficult to hone big ends or even pin ends and hold them true and without a taper one way or the other....

I would chuck the mandrels up in a lathe and true up the brass guide shoes often and dress the stones....constantly...

I used the gauge to check the rod and as described held it flat and carefully pulled it away from the back reading the size. A very tedious process......honing to size and keeping them as straight as possible....

I always honed rods and let them sit and they change size as the honing process heats them up.....let 'em cool and touch 'em up....

A buddy had a shop with a similar machine but with a power stroker and I don't know if that helped as I think it did pairs of rods at one time...

Honing anything was a time consuming process if you were trying to do as good as possible....

I marvel at the Youtube videos of Block hones that do a V8 without an operator constantly running the machine and checking the bore sizes....

Honing a race block and doing a real good job was the shop owners specialty along with head work.....Any block he honed made better power than previously usually....



I also rebuilt Mack connecting rods a lot......new bushings mostly....big ends were usually pretty good even after a half million miles ! Engines in UPS trucks....

Re: Mopar 383 Connecting Rods
 

I have a nice LBB-1499 with the AG, not sure when they were made but I'm thinking 60s. I did hundreds of rods on an old bench top Sunnen in a shop I used to work at, not sure what model it was. It's an art that definitely takes time and talent to master.

Re: Mopar 383 Connecting Rods
 

''It's an art that definitely takes time and talent to master.'' How true!

Re: Mopar 383 Connecting Rods
 

Kinda' like block honing.

Re: Mopar 383 Connecting Rods
 

Any size target honing is the artform, "damn I honed to much wont fix it".

Re: Mopar 383 Connecting Rods
 

Ya can’t put metal back so ya gotta sneak up on it !

Re: Mopar 383 Connecting Rods
 

You have two rods your honing..........theres .0025 to hone to size on both rods, one rod has .0005 taper the other has .0007 taper. How do you set these two rods up on the already trued mandrel?

Re: Mopar 383 Connecting Rods
 

Does the cap grinder cut the cap 90* to the bore? At .0006 taper per inch, it would taper .0072 per foot. That's a lot.

It might take truing the mandrel a few times to get rod to size using a slightly lower stone pressure.

If accepted size is 2.5000 to 2.5005 is any size on or between good or is there a taper tolerance " Tapper not to exceed .........."

Re: Mopar 383 Connecting Rods
 

Please pardon, I adjusted your post for clarity.
Okay, I'll play. We're just having fun here........Right?
Let's assume you cut the mating surfaces and are resizing the rods in your example.
Let's again assume you cut the mating surfaces enough that you started from a dimension smaller than you currently have (-.0025). And you honed the rods to this dimension.
Once again, let's assume that you find the taper begins at the surfaces you were holding together, and progresses outward on both rods.
And yet again, let's assume that you have been flipping this pair of rods over every half thousandths or so. You do flip your rods over don't you?
Still yet again, let's assume that you have not been over-stroking the rods beyond the honing stones too much.
One more assumption, let's assume you are honing those rods with the beams riding on separate torque bars, not the same bar.
There are still a few more things to assume, you did deburr the bolt holes at the parting line, you did make sure that the cheeks of each re-assembled rod was...were...are... flat. Because, after all that work you don't want the pair of rods you are trying to hold together to be a couple of "rocking horses".


Answer: When that happens to me, I push the "OFF" button and walk away for a while. Because it's a clear case of operator error.
What did Dirty Harry say?

Re: Mopar 383 Connecting Rods
 

[QUOTE=Larry Hill;602288]Does the cap grinder cut the cap 90* to the bore? At .0006 taper per inch, it would taper .0072 per foot. That's a lot.

It might take truing the mandrel a few times to get rod to size using a slightly lower stone pressure.

If accepted size is 2.5000 to 2.5005 is any size on or between good or is there a taper tolerance " Tapper not to exceed .........."[/QUOT


The cap cutter would be dialed in @ 90 degrees, setup with the horse shoe.

How would the rods be put on (position) the mandrel at the start of the honing?

Chevrolet BBC rods from the factory sometimes the mating surface is not 90 degrees to the sides, which will cause taper when the mating surfaces are cut.

Re: Mopar 383 Connecting Rods
 

"let's assume that you find the taper begins at the surfaces you were holding together, and progresses outward on both rods"



If your saying, and I think you might be, the first rod with the taper tight (facing the operator) would go on the mandrel first, the second rod with the taper tight up would go against the first rod. So the tight side of the housing bore would always go against each other until the taper is gone, typical flipping would start from there.

Re: Mopar 383 Connecting Rods
 

I never honed pairs of rods and did one at a time.
Focused on the one in my hand and not trying to juggle 2 and work out the taper(s) using two.

Is it better to use the 2 rod method.....?
I don't know its been nearly 30 years since I left the engine machining world and I'm not returning anytime soon. No one in the shop I worked at used the 2 rod method.

If its better I missed the memo back around 1970 something....lol

There is and always was an endless string of potentially poorly OEM machined items in an engine. Starting with the block itself and right on down the line.
Correcting or attempting to correct much of it would be very difficult if not impossible sometimes.

Engine machining has definitely advanced a lot with better machines and fixturing and mostly parts....

I was in a shop yesterday.....Didn't look all that different than where I worked 30 years ago...….Mostly Older machines, heads, blocks and stuff everywhere.....

2 Jaguar heads, A complete out of car Mopar Poly engine and a flat head Ford block just a few things I spotted.....

Re: Mopar 383 Connecting Rods
 

I agree many rods, not just BBC, don't have the housing bore and sides perpendicular to the parting line. My personal opinion is that we often find rods (especially OEM) that also don't have the sides parallel to each other. If that is the case then one side will be closer to "square" than the other.

We understand that we will hone, more or less, perpendicular to the rod sides. The cap cutter should cut the parting line perpendicular to the sides. Therefore we need to prepare the sides, to the best of our ability, before we cut the parting surfaces. Then we need to check the parting surfaces before we cut them. How did we remove the pressed in bolts? Did we twist the forks doing that? Are there burrs or dings anywhere?

Only then do we begin to cut the parting surfaces. Production "guys" will touch off on one rod,or cap, dial in the amount they want to remove, and make their cuts.

I prefer to touch off every rod and cap, every time, and observe the cut surface to see if it's cutting "flat". If not, I turn the part around to square off the other side and touch it again. I pick the best side and cut the amount I prefer.
Then we get to prep our newly machined surfaces. Reinstall the press in rod bolts, again trying not to twist the forks. Reinstall the cap(s), torque the bolts using a procedure we can repeat on final assembly. And make sure the sides are flat so that the rods don't "rock" as we hold the pair on the hone.
After that, it's up to the hone operator to do his job. The prep work is "just machining", the honing is where the "touch" comes into play.

All in all, it's not easy, or cheap, to do the job right.
Then if we want to have "fun" let's do some rods that the need to be "saved". You know....the blue ones.

Re: Mopar 383 Connecting Rods
 

Well....:Dwhat I'm actually saying is that if you have been honing a pair of rods, and the smallest points of the taper begin at the surfaces you have been holding together, and the mandrel is straight....
Let's try to get on the same page. Front rod tapered out towards you. Back rod tapered out away from you. Okay.....Right?
....the rods are tapered from operator error. The person operating the hone is twisting or torquing the rods on the mandrel.

Regarding "flipping" the rods. Sometimes you put the front rod in the rear (opposite the way they run). Sometimes you rotate the front rod 180 degrees and the back rod 180 degrees (opposite the way they run). That's what I do every half thousandths or so.

Flipping the rods not only helps keep the rod bores straight, it helps keep the mandrel wearing straight.

Re: Mopar 383 Connecting Rods
 

No, but you double the length. Makes it easier on the operator.
I like to finish the rods in pairs as they will run in the engine. Does it make a difference? I dunno....makes me feel good.

Re: Mopar 383 Connecting Rods
 

This reminds me of the "how to read a mic" argument that went on in the first shop I worked at …..Tony Feil's.....1966.....

2 employees that just couldn't agree on some detail of using a micrometer.....

I was just a green teenager that knew very little...and I don't recall exactly what the disagreement was about but it was bad.....

I wouldn't really mind honing some rods as long as I'm warm and we have music.....gotta have music....and coffee.....and cigarettes for sure back in the day......lots of coffee and lots of cigarettes....lol

Re: Mopar 383 Connecting Rods
 

"Let's try to get on the same page. Front rod tapered out towards you. Back rod tapered out away from you. Okay.....Right?"

YES. very few understand this

Re: Mopar 383 Connecting Rods
 

Its also how you keep the mandrel true, its always about working the mandrel when honing.

Re: Mopar 383 Connecting Rods
 

''The cap cutter should cut the parting line perpendicular to the sides. Therefore we need to prepare the sides, to the best of our ability, before we cut the parting surfaces.''

The best way I have found to make thrust sides close to 90* to the bore is to make a mandrel and face each side of the rod on a lathe. The mandrel will have one rod on it for balance while the second the rod is being cut.

So how much rod side clearance is too much?

Re: Mopar 383 Connecting Rods
 

Why bother with 40-50 year old stock junk when there are so many new rods available.By time you magnaflux, check for straightness, rebuild with better rod bolts, and bush the small end you could buy much better newer rods. And yes I've rebuilt stock rods with better rod bolts and couldn't keep the housing bores round.

Re: Mopar 383 Connecting Rods
 

I agree, back in post #13.

Re: Mopar 383 Connecting Rods
 

Preaching to the choir.
But it seems that guys who are hot rodding big block Chevys and MoPars tend to stick with stock rods. Small block Chevys....you can't give away stock rods....literally. Come by if you want some.

Re: Mopar 383 Connecting Rods
 

I got an e-mail from Molnar rods that Tom Molnar will submit his 383 Mopar rod (w/BBC big end, stock length) to NHRA for SS approval. Nothing for the Stocker guys with the 383. I've been told that Hale is trying to get Manley to run another set of his rods (stock pin and big end sizes).

Re: Mopar 383 Connecting Rods
 

Y'all need to teach your customer's what is needed and better for them.....lol

Re: Mopar 383 Connecting Rods
 

Larry Hill

What is this instrument used for in a machine shop?

Re: Mopar 383 Connecting Rods
 

Could be to check connecting rods for straightness.

Re: Mopar 383 Connecting Rods
 

Another angle of view.