Mopar 383 Connecting Rods

[Tom Broome]

Originally Posted by HP HUNTER

You have two rods you're honing..........there's .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?

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?

[HP HUNTER]

Originally Posted by Tom Broome

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?

"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.

[Tom Broome]

Originally Posted by HP HUNTER

"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.

Well....what 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.

[HP HUNTER]

Originally Posted by Tom Broome

Well....what 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.

"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

[Larry Hill]

''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?

[Glenn Briglio]

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.

[Tom Broome]

Originally Posted by Glenn Briglio

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.

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.