twayne24365
Well-Known Member
So ive always hear to have a mopar bored and honed with a torque plate, i just wanted to hear some opinions since i will be taking my block to the shop in another week. This is a 440 btw
Torque plate
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Purple Haze
Well-Known Member
Absolutely, If you want nice round cylinders when the heads are on and torqued down.
X's 2
twayne24365
Well-Known Member
Do they use the plate during boring and honing?
Purple Haze
Well-Known Member
If you tell them thats what you want.
moper
Well-Known Member
Not during boring. Only during honing.
Why not during boring? I would think that you would also want it when you bore, to keep the cut straight.
When you tighten the torque plate, it distorts the block, and you want that when boring as honing is not meant to remove any metal as much as just to "scuff the surface"....
If the block distorts when the torque plates are secured it may need to take off more metal than the hone is designed to do....
femtnmax
Well-Known Member
Some shops advertise torque plate bore and hone. Maybe just a purist but I'd be all for it if they can do it.
In my experience the blocks with only 4 head bolts per cylinder have/can have problems with bore distortion when the head bolts are torqued down....These type blocks seem to really benefit from torque plates, such as Ford FE and small block Mopar.
moper
Well-Known Member
The distortion is around a couple thousanths in the areas around the bolts. The boring gets it within a few thousanths of final bore size so you can do it with the plate. But it's just more work to bore with the plate, take it apart, wash the block, then reassemble and hone it. That's assuming the shop has two plates otherwise it's a lot more work - remember it has to be correctly torqued each time it goes on. Honing is what brings the bore slowly up to the final size. Honing needs to be done with that distortion occurring. Boring simply doesn't.
On the block line that I worked on, we did 3 passes for the bore, and only one for the hone. The hone doesn't take off much metal, it's just to put the surface finish on the cylinder. We started with raw castings and made fully machined finished blocks with freeze plugs and cam bearings ready to assemble when finished.
moper
Well-Known Member
Understood. How long ago was that? Did they own a good profilometer?
I've built engines that were plate honed, but when measured the bores were straight and round all the way up to the deck without the heads in place. There should be a measureable distortion without the heads if it's done properly. The shop I use bores with the main caps torqued but no deck plate, using one or two passes depending on the amount being removed to within .002 of finish size (Rottler F86A CNC mill so feed rate and spindle rpm is completely adjustable). The rest is taken off a little at a time by the honing process.
To expand on what you said about honing - honing takes the sharp edges left after boring off the cylinder wall surface and preps that surface for the rings to seat quickly and seal. While it does remove material, it's less and less with each pass and there are course and fine stones and brushes which when combined with the rpm, speed of the stroke, and pressure on the abrasives get the desired finish for the rings you want to run. It's not really a "pass" but a series of strokes with varying grit abrasives, varying speeds, and varying pressures on the walls. When it's all said and done properly the bores will measure tighter and out of round at the top where the bolt bosses are cast.
I've built engines that were plate honed, but when measured the bores were straight and round all the way up to the deck without the heads in place. There should be a measureable distortion without the heads if it's done properly. The shop I use bores with the main caps torqued but no deck plate, using one or two passes depending on the amount being removed to within .002 of finish size (Rottler F86A CNC mill so feed rate and spindle rpm is completely adjustable). The rest is taken off a little at a time by the honing process.
To expand on what you said about honing - honing takes the sharp edges left after boring off the cylinder wall surface and preps that surface for the rings to seat quickly and seal. While it does remove material, it's less and less with each pass and there are course and fine stones and brushes which when combined with the rpm, speed of the stroke, and pressure on the abrasives get the desired finish for the rings you want to run. It's not really a "pass" but a series of strokes with varying grit abrasives, varying speeds, and varying pressures on the walls. When it's all said and done properly the bores will measure tighter and out of round at the top where the bolt bosses are cast.
nitrojunkee
Well-Known Member
I've never not had the final hone done with a torque plate, no matter what the engine family. I just had my 496 done that way with head studs... Squared, decked, align honed, torque plate... Studs throughout. That's what I do.
moper
Well-Known Member
Years ago I had to buy my own Mopar big block and small block plates...lol. I still have them. Of course back then they were using boring bars and hand honing for iron rings...
CPMotorworks
Well-Known Member
IMO shops that bore within .002" then hone are taking shortcuts. You have to leave enough material to use a series of stones, in order to leave the subsurface with the proper depth of cross hatch to hold the oil. AKA Rvk value.
I see alot of blocks come in that have been shallow honed and the cylinders are glazed and missing the crosshatch from not being able to hold the oil on the bores properly.
Like Moper said- its a bunch of work and adds another accuracy issue to bore and hone with a plate.
I personally leave .005"-.007" depending on the block and bore size, and just finish hone with a plate.
A good hone is designed to make round holes, and can take out material very fast with the right stone and operator. I've taken several blocks and honed them .010" to the next size starting with an 80 grit stone.
I see alot of blocks come in that have been shallow honed and the cylinders are glazed and missing the crosshatch from not being able to hold the oil on the bores properly.
Like Moper said- its a bunch of work and adds another accuracy issue to bore and hone with a plate.
I personally leave .005"-.007" depending on the block and bore size, and just finish hone with a plate.
A good hone is designed to make round holes, and can take out material very fast with the right stone and operator. I've taken several blocks and honed them .010" to the next size starting with an 80 grit stone.
moper
Well-Known Member
Pete - It's just my opinion but the accuracy and adjustability of the miller's cutter allows for that shortcut. They also have a Rottler CNC power honing cabinet and have used the two of them, the profilometer, and the dyno to dial in their wall finishes. I've yet to have any ring seal or oil use issues with any block they've done for me, even the couple that predate the honing cabinet. Some of those rebuilds are upwards of 50K on them now.
We had plenty of gauges. Our line ran 500,000 engines per year for daily drivers. We also had a CMM (Coordinate Measuring Machine) room in our inspection department that we also could get things measured on.
Each pass on the bore took off less and less metal. Our rule was that you use the boring operations to get you to the proper size, then "scratch the surface" with the hone. You just take a little bit off with the hone, but it's mostly to get the surface finish to spec.
When they changed over to the "smooth bore", I was the one who had to have everything measured and submit all results to the design group for their approval before launch. (mid-year launch at that - not a clean break between model years :banghead
. Diameter and surface finish at 10 levels of the bore every 45° in each cylinder. :violent1:Challenger340
Well-Known Member
We had plenty of gauges. Our line ran 500,000 engines per year for daily drivers. We also had a CMM (Coordinate Measuring Machine) room in our inspection department that we also could get things measured on.
Each pass on the bore took off less and less metal. Our rule was that you use the boring operations to get you to the proper size, then "scratch the surface" with the hone. You just take a little bit off with the hone, but it's mostly to get the surface finish to spec.
When they changed over to the "smooth bore", I was the one who had to have everything measured and submit all results to the design group for their approval before launch. (mid-year launch at that - not a clean break between model years :banghead
Interesting stuff
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