torque plate honing, line honing, how many types are there, i posted thing before but no one really told me, i know that they use the clayish stuff to do it though

 

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Honing: some thoughts.

Cylinder bore honing is the most critical honing operation on an engine. The process is used to generate the final bore diameter (size), as well as roundness and straightness. It is done after boring to within maybe .005 of final size.

Torque plates, or honing plates, bolted or studded to the block with a head gasket are used to simulate the head loads and distortion of the bores when the engine is assembled. Honing with the torque plates makes the holes round in their assembled state, even though they may not be round when the block doesn't have heads on it.

The other critical thing cylinder bore honing accomplishes is to establish the surface finish and cross-hatch pattern which makes for the best piston ring seal. What this should be depends a lot on the rings used, and the engine parameters in general. IMO, asking the ring manufacturer for recommendations is the way to go. Total Seal gives exact procedures including stone part numbers, grits, stroke speed, hone speed and number of strokes with each stone.

"Line honing" or align honing is used on the block main bearing bores (with bearings removed, of course) to get them back in line. Usually, a few .001's of a inch are removed from the main bearing caps, which makes the bearing bores small in the vertical dimension. All five (in a modern V8) are then honed simultaneously with a long hone mandrel to get them on the same axis or in line. The newly aligned bearing bores are then used to locate the block for further machining operations.

Connecting rod honing is used to rebuild con rods or to fit floating pins in the small end. If the caps have machined faces, they can have a few .001's removed (like the main caps) and then honed to original size. If new "fractured" caps are used (LS1, etc) you can't do this. The small ends may have bronze bushings for floating pins. The bushings are honed for the correct fit with the pins. This is usually the most precise sizing in the engine, because the clearances are only a few .0001's (ten-thousandths) of an inch.

Valve guides may be honed when new ones are installed.

Lifter bore bushings, if used, may be honed.

I suppose you could align hone the cam bores, but I think that's not often done. There's not the kind of loading that distorts them and they are in a fairly strong area of the block.

All of these honing operations use abrasive stones which are forced outward under pressure toward the surface being honed. There are also shoes, usually opposite the stones which support the load. Honing can generate a straight, round hole if it is done correctly.

The "bottle brushes" or flex hones with many abrasive ***** on the end of each spoke can be used to generate a surface finish. The won't remove much stock, and they won't make the hole round and straight. They will also help deburr a bore with cross holes like a lifter bore.

There's also "extrude honing", which uses 'the clayish stuff' with imbedded abrasive grains forced through something like a manifold under high pressure. The abrasive removes the high spots, and if done aggressively, some metal all around the hole. It selectively removes the biggest restrictions, so it's a nice finish porting tool. The process is unlike all the other honing processes above. I think "abrasive extrusion machining" might be a better term, but that doesn't have the appeal of "Extrude Honing".

Probably more than you wanted to know SevenSeven.

 

thanks, i was just wanting to learn all i could about it, thats exactly what i wanted to know, thanks again

 

Great write up oldSStroker! Have you seen the new rod bearing for the "cracked " rods, they offer a larger bearing od.

 

Theres also hot-honing -- heating the block up to & maintaining operating temp throughout the duration of the honing process.

 

cool

 

I'm not sold on hot-honing yet. While it may be true that you can make the bore more like what it is when it's running, I am concerned that you can't get as accurate a piston fit as with room-temp honing.

At 180*F, the bore grows about .0025 from room temp. What temp measuring tools do you use? If you use contact gages like a dial bore gage, you need it and it's master ring to be at honing temp. That's tough on the operator. Not many folks have non-contact air probe bore gages which might be more accurate here.

I wouldn't put it past Cup engine shops to do this, however.

I've thought that torque plates really don't replicate the exact bore distortion either, because they are usually solid steel plates with 4 inch+ holes through them, and most heads are aluminum castings full of holes.

IMO, maybe we're picking nits.

My $.02

 

I forgot about those. Thanks for the reminder.

"Oh, by the way, Clevite, I need .25 mm under ID and .1 mm over OD rod bearings, please. Or was it the other way around?"

 

When hot honing, you'll generally have 220 deg coolant at 25 psi flowing through the block, as well as keeping your honing oil at 200 degrees. One of the problems the engine builder (Billy The Kid, up in Torrington, CT, builds lots of Busch North & Modified engines...) mentioned was the bore gauge heating up from the hot block, and growing. They've got a growth correction factor they'll use to convert to the cold bore temperature. All 'cup teams do this as from the few nascar folks I've spoken to, and many of the Busch series guys have blocks hot honed as well. I think at that point, what's a $300 hone on a $40k engine? Circle Track or Stock Car Racing had a great article about it about a year ago.

Andris, with a hot honed Dart Little M block...

 

Somehow, this thread managed to salvage its place on Advanced Tech, when the replies digressed into some of the newer technology.... otherwise, it seems to me that these "basic" questions like "what is........" should be researched in some basic engine building books, rather than expecting people to prepare a "Honing 101" class and serve it up on a platter.....

Just an observation. Any other thoughts - pro or con?

Fred

 

Thanks for the info.

The growth correction factor should be about 6 millionths of an inch per inch of bore diameter per degree F. For a Cup engine, that's almost .004.

Honing cast iron is not a clean job anyway, but now it's a hot, dirty job.

I hope they pay those block guys well. $300 sounds cheap to me.

 

I agree about the basic questions, Fred. I was surprised the thread hadn't been moved before I first posted.

A couple of points:

If one doesn't know the answer, there's no such thing as a stupid (or too basic) question. The questioner might not know where to look, so he visits a forum. Maybe not the exactly correct forum, but we've both seen threads like this take a neat turn.

I've gotten some new information from it, and maybe some Advanced Tech posters or lurkers have also.

I've also seen much mis-informaton posted on less technical forums. Maybe folks come here for good, current, info. I do.

The great thing about forums (and one of the biggest problems with being a moderator, I'll bet) is that some threads develop a life of their own. That's what makes a given forum interesting, at least to me. I get tired of "what LCA should I choose for next week's cam" threads.

I think you do a good job of moving threads.

My $.02


Jon