[Shiny]

Originally Posted by mgarblik

Finally had some time to work on the connecting rods for this SD engine. I installed the ARP bolts and stretched them to .0075" stretch as directed by ARP. Then measured the big end housing bores. Each housing bore closed up .0015"-.0018" smaller than the spec. This is NOT unexpected. The ARP bolts are much stronger than even the stock SD bolts and have higher clamping load. The torque to reach that stretch was around 90 ft. lbs. So as a general rule, on any connecting rod, when changing the bolts, plan on honing the rod big ends back to specs. to get nice straight and round bores for the bearings. Should be a fairly easy fix. Will make that happen today and move on to a little block hone touch-up. Then a thorough cleaning.

I apologize for the diversion and ignorance but can someone explain the tools/methods used to hone a rod bore?

I want to understand how an abrasive machining process can return this heavily distorted bore to round. These bolts must apply a LOT more compression than stock bolts to get this much change.

Are the abrasives "rigid" and gradually expanded instead of just following the bore with spring-loaded stones?

Not being familiar with the equipment used, I have a vision of spring-loaded stones which I'd expect to just follow whatever shape is already there. This has to be wrong.

Is a rod hone more like a rigid grinding wheel that is expanded as it progresses?


Mike

[mgarblik]

The connecting rod hone is a fixed stone, eccentric style hone. You grind the cap and rod at the parting line to give you material to remove. The honing head runs pretty slow and it is a hand process. The secret to getting perfectly round and taper free big ends lies in the process. You hone the rods in pairs. This covers more of the stone. You move the rods over the stones with a prescribed stroke speed and pressure, say 5 strokes to start. Then you swap the front and rear rod position and do 5 more strokes. Then you flip the rods over and do 5 more strokes. Then you switch inside and outside for the final 5 strokes. That completes 1 cycle. Then measure. As you get close to zero, the number of strokes decreases, possibly down to 1. This gets every part of the rod on every part of the stone. Once you get the hang of it, the rods can be made near perfect. 0.0000 +- .0001" is not that difficult. You want 60% or more of the rod right on spec. The parting line +- 10% on each side will be large on purpose. This is to prevent pinching and spinning a bearing under extreme load. Each reconditioning procedure does make the rods effectively shorter. So that needs to be addressed with your deck height and so forth for a race build. Hope this makes sense.

[Elarson]

Originally Posted by mgarblik

The connecting rod hone is a fixed stone, eccentric style hone. You grind the cap and rod at the parting line to give you material to remove. The honing head runs pretty slow and it is a hand process. The secret to getting perfectly round and taper free big ends lies in the process. You hone the rods in pairs. This covers more of the stone. You move the rods over the stones with a prescribed stroke speed and pressure, say 5 strokes to start. Then you swap the front and rear rod position and do 5 more strokes. Then you flip the rods over and do 5 more strokes. Then you switch inside and outside for the final 5 strokes. That completes 1 cycle. Then measure. As you get close to zero, the number of strokes decreases, possibly down to 1. This gets every part of the rod on every part of the stone. Once you get the hang of it, the rods can be made near perfect. 0.0000 +- .0001" is not that difficult. You want 60% or more of the rod right on spec. The parting line +- 10% on each side will be large on purpose. This is to prevent pinching and spinning a bearing under extreme load. Each reconditioning procedure does make the rods effectively shorter. So that needs to be addressed with your deck height and so forth for a race build. Hope this makes sense.

And that right there is the difference between a real engine builder and the "machinist" in the back room at Acme Auto Parts.

Eric

[steve25]

And Acme auto parts sells to the Coyote and I bet you have seen how many times things fail for him and the road runner goes on his merry way!

[mgarblik]

I did weigh the SD block today. Digital shipping scale. I think it is +- 1 lb. I weighed myself and it was the same as my bathroom scale. Bare block weighs 174.50 lbs. Main caps and bolts weigh 16.5 lbs. Not sure how that compares to other stock block Pontiacs. Chime in.

[sdbob]

I too wanted to weigh a SD455 Block. Before I sold the white auto SD. I weighed the block on a state certified scale. The block std bore, had all main caps and bolts, no freeze plugs. 195#. I didnt look for the 'mountain'.

[Shiny]

Originally Posted by mgarblik

The connecting rod hone is a fixed stone, eccentric style hone. ......Hope this makes sense.

Thanks for taking the time to explain.

I'm still too ignorant to know what an "eccentric style" hone is, but I'll look that up. I still don't understand how the material removal can be "selective" around the circumference of the bore but obviously it is, at least with you as the machinist!

The experience factor needed to get your results sounds significant... something as seemingly simple as doing two at a time to distribute the loads and reduce taper probably isn't obvious to many.

Impressive results!

Mike

[mgarblik]

I am going to try and attach a Youtube link that shows the machine in operation.

You can see the off center running of the honing machine clearly. The operator doesn't have a smooth stroke or pattern which makes perfect results difficult. He also is doing one at a time which is slower and typically produces some taper and wears the stones unevenly. But at least you sort of get an idea of how the process works.


https://www.youtube.com/watch?v=j5UqmpMME88

[Shiny]

Thanks again Mike

I've still got lots of questions but won't destroy this great thread.



Mike

[mgarblik]

I have weighed a few other SD parts vs regular 73 455 parts for general knowledge. Basically the the weight of the crankshaft and the block are statistically insignificant in difference. The bare blocks were SD-455 174.5 lbs. and the regular 455 was 175.35 lbs. The regular block did have freeze plugs in it and a dipstick tube. So really the same weight with all those strength enhancements. The crankshafts were SD-455 72.1 lbs. Regular 455 was 72.35 lbs. The cranks look virtually the same. Possibly a tiny bit more radius on the SD crank but it was ground .010-.010, so really can't say. No chamfer on the SD oil holes at all. Nothing special there. Going to begin reassembly soon.

[hurryinhoosier62]

Originally Posted by mgarblik

I am going to try and attach a Youtube link that shows the machine in operation.

You can see the off center running of the honing machine clearly. The operator doesn't have a smooth stroke or pattern which makes perfect results difficult. He also is doing one at a time which is slower and typically produces some taper and wears the stones unevenly. But at least you sort of get an idea of how the process works.


https://www.youtube.com/watch?v=j5UqmpMME88

X 2, Mike. The one thing we did was to allow the rods to cool back to room temp before starting the final hone. On a side note, I like to figure out how much honing oil my skin has absorbed over the years!

[4dblnkldude]

Been reading since the beginning. This is why this board trumps most all the other boards, fb, etc. Detailed, well explained from a guy willing to teach.

[mgarblik]

Originally Posted by hurryinhoosier62

X 2, Mike. The one thing we did was to allow the rods to cool back to room temp before starting the final hone. On a side note, I like to figure out how much honing oil my skin has absorbed over the years!

Yes, letting them cool is important. Agree 100% Automotive rods will shrink .0002"-0003" once cooled. Sound about right? The oil probably isn't great for your skin, I imagine. But I think gloves would be a real danger in honing by hand like that. I could easily see a glove getting stuck or torn off from a stone or guide.

[jhein]

Originally Posted by 4dblnkldude

Been reading since the beginning. This is why this board trumps most all the other boards, fb, etc. Detailed, well explained from a guy willing to teach.

The amount of knowledge and experience (and the way people share it) on this board is fantastic. Very impressive.

[Dragncar]

PY has always been "The Best".

[PAUL K]

Originally Posted by Dragncar

PY has always been "The Best".

X 2

[mgarblik]

Little build update. Finally had time to install and degree the camshaft. Then install the rings, pistons and connecting rods. A few specs. for the engine guys. Pistons measure -.005 to -.007" down in the bores. Better than I expected. I did use a Cloyes billet timing set with 9 keyways vs the 4-cylinder reinforced flat link chain that was installed. I will likely sell that set soon. It was just too stiff for my personal liking and the Z-Chain Cloyes set has been my choice for years now, holding up incredibly well in the most abusive use possible. With the sprocket advanced 2 degrees, I settled with 107.75 degree installation. I am re-using the piston rings and had to tweak the end gaps just a little on a few rings. With my minor re-hone the gaps are just slightly wide, but I am fine with them. Top ring .021-.022". Second .022-.023". Next, I need to stretch the rod bolts for the final time. ARP wants .0065-.007" stretch which is 85-90 ft. Lbs. from by little tests. That's plenty tight and difficult to pull with an end wrench and the stretch gauge in place. More up-dates to come.

[steve25]

Have you folks ever used the laytex protection cream on your hands ?
I find that stuff gives near as much protection as gloves, but if your hands sweat it will desolve the cream somewhat.

[mgarblik]

Originally Posted by steve25

Have you folks ever used the laytex protection cream on your hands ?
I find that stuff gives near as much protection as gloves, but if your hands sweat it will desolve the cream somewhat.

I have not heard of that product. I will have to look it up. I do wear gloves when I am doing very dirty work.

[Dragncar]

They used to issue stuff like that at a pulp mill I worked at for a bit. All sorts of nasty chemicals in those places.
Those mills are gone around here. I used to be sad about it, not anymore.
The air and water is cleaner now.
You would not believe all the toxic chemicals involved in making paper.