CYLINDER MACHINING QUESTION

[CFD244]

Hi Folks

Will a factory .020 oversized bore that is currently 4.0645 with .003 of taper and less than .001 out of round clean up to 4.070 with a machine shop honing, or does it need to be bored first? Cylinders show no signs of mechanical damage or rust pits. It's just worn out. New rings yield a .050 gap. Thanks.

 

[66fs]

If you are doing a budget rebuild with your used pistons, have it honed (preferably with a torque plate) till it just starts "scratching" the lowest wear at the top of the cylinder. Measure and make your decision from there. If you are buying new pistons, bore and hone for the tighter fit.

 

[CFD244]

If you are buying new pistons, bore and hone for the tighter fit.

Thanks, that was my question. Will go to .030 pistons, but wasn't sure if it could be hone to the final size, or if it needs to be bored first. Basically asking what a hones capabilities are.

 

[Oldmanmopar]

I asked my son. He said It could be honed with a power hone. But if it was here at our shop he would install torque plates and do a scratch bore to get it closer. You need the pistons to do the finish hone so you can size the bore. And you may go over 4.070 depending on the piston size. Everything done here is with 2 torque plates installed

Why he said he wouldn't just hone it to size first? Is due to the wear on the stones. Doing tapers bores may show up on the stones after the first couple cylinders The out of round also causes a problem and I don't remember what he said. I won't call him back he is decking a block so he is busy.

He does several blocks here for performance and race vehicles. All types even Bikes. I would trust what he says.. Bore it, Then Hone it to size

Doing a budget build only cost more in the future when it entails performance engines. 340? not a 318 Think about it New pistons?. why go cheap with the main heart of the engine.

 

[CFD244]

I asked my son. He said It could be honed with a power hone. But if it was here at our shop he would install torque plates and do a scratch bore to get it closer. You need the pistons to do the finish hone so you can size the bore. And you may go over 4.070 depending on the piston size. Everything done here is with 2 torque plates installed

Why he said he wouldn't just hone it to size first? Is due to the wear on the stones. Doing tapers bores may show up on the stones after the first couple cylinders The out of round also causes a problem and I don't remember what he said. I won't call him back he is decking a block so he is busy.

He does several blocks here for performance and race vehicles. All types even Bikes. I would trust what he says.. Bore it, Then Hone it to size

Doing a budget build only cost more in the future when it entails performance engines. 340? not a 318 Think about it New pistons?. why go cheap with the main heart of the engine.

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Thanks for the reply. I wasn't sure what the capabilities of the hone were. I am starting to think that there is no such thing as a budget build. Definitely want to do it right that's for sure.

 

[toolmanmike]

I asked my son. He said It could be honed with a power hone. But if it was here at our shop he would install torque plates and do a scratch bore to get it closer. You need the pistons to do the finish hone so you can size the bore. And you may go over 4.070 depending on the piston size. Everything done here is with 2 torque plates installed

Why he said he wouldn't just hone it to size first? Is due to the wear on the stones. Doing tapers bores may show up on the stones after the first couple cylinders The out of round also causes a problem and I don't remember what he said. I won't call him back he is decking a block so he is busy.

He does several blocks here for performance and race vehicles. All types even Bikes. I would trust what he says.. Bore it, Then Hone it to size

Doing a budget build only cost more in the future when it entails performance engines. 340? not a 318 Think about it New pistons?. why go cheap with the main heart of the engine.

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Exactly! Honing is just to finish the bore after machining not to correct out of round, taper, and roughness.

 

[74 360 dart sport]

It will be cheaper in the end to bore it and do it right it would be the ****'s if you hone it and you get it all back together and it burns oil

 

[Killer6]

Hi Folks

Will a factory .020 oversized bore that is currently 4.0645 with .003 of taper and less than .001 out of round clean up to 4.070 with a machine shop honing, or does it need to be bored first? Cylinders show no signs of mechanical damage or rust pits. It's just worn out. New rings yield a .050 gap. Thanks.

If there aren't any "anomalies" it should, but that close hard to guarantee, if You are going forged slugs the extra .004" or so of clearance needed the odds are much better.
Torque-plate, boring bar run, hone, finish-hone, plateau brush depending. They need the slugs, and to know exactly what rings/type You're using.

 

[66fs]

It will be cheaper in the end to bore it and do it right it would be the ****'s if you hone it and you get it all back together and it burns oil

If you have a good hone, there are no worries with a light hone up to 4 or 5 thousandths over nominal. Using good rings of course.

 

[Rat Bastid]

Hi Folks

Will a factory .020 oversized bore that is currently 4.0645 with .003 of taper and less than .001 out of round clean up to 4.070 with a machine shop honing, or does it need to be bored first? Cylinders show no signs of mechanical damage or rust pits. It's just worn out. New rings yield a .050 gap. Thanks.

Yes. If the machine shop can’t do that, find another shop.

 

[Outsder]

Doable, rough stones to get cyl round, dress stones after each cyl, then finish with a couple stages of fine stones for final size and finish.

 

[Inertia]

I know I'm going to get flamed here.
To do a "proper" job, mosta all of above is correct.
Experience has shown me after being taught at school, been mentored and having performed by myself and misc employees, that an "over the fender" overhaul with a hand held 3 stone hone, on dozens and dozens of engines, then service those engines for decades more, and have few problems, that THEN need expensive removal and machining.
It was common "back in the day" for a valve grind at 80,000ish miles, and a re-ring at 120,000ish miles, around the world .
Flame on . .

 

[Charrlie_S]

If you have a good hone, there are no worries with a light hone up to 4 or 5 thousandths over nominal. Using good rings of course.

I disagree. I do a lot of budget rebuilds, without reboring, just honing. A hone is not for enlarging the cyl bore, it is for putting the proper finish on the bore. A hone is not designed to remove thousandths of an inch, but less than one thousandth.
If you want to do it right, bore and new pistons, and rings. Have it honed to get the proper finish for the rings used.
If you want cheap, just hone it (to break the glaze), and put it together with a cheap set of rings. It will work, but won't last as many miles, or seal as well as the good job.
You need to balance money vs results.

 

[66fs]

I disagree. I do a lot of budget rebuilds, without reboring, just honing. A hone is not for enlarging the cyl bore, it is for putting the proper finish on the bore. A hone is not designed to remove thousandths of an inch, but less than one thousandth.
If you want to do it right, bore and new pistons, and rings. Have it honed to get the proper finish for the rings used.
If you want cheap, just hone it (to break the glaze), and put it together with a cheap set of rings. It will work, but won't last as many miles, or seal as well as the good job.
You need to balance money vs results.

Sorry, done this too many times and know it works. I have a Sunnen hone. If you have a block with little wear, and they don't wear even, you can straighten the taper and get them round with a good hone. I'm not talking dingle berry hone or cheap straight stone hone. How much do you think they leave after a bore to hone the final size and finish in a cylinder? Nothing wrong with new pistons, bore and hone. It is just time and money and yes, you should have a tighter fit. But I'm here to tell you I have, and have built engines for others, that run out fine with a short block that had .004 to .005 clearance, reusing pistons, and Speed Pro file to fit rings. I have three such short blocks I will be rebuilding this way. A 273, a 340 and a 318 magnum because they each have such little wear in the block. My engines have plenty of power and have yet to have one not run very good or last at least 200,000 miles. As a matter of fact, I've never had one die. I usually am swapping engines because I want to try something else or gas octane took a nose dive and I had to lower compression.

 

[Charrlie_S]

Sorry, done this too many times and know it works. I have a Sunnen hone. If you have a block with little wear, and they don't wear even, you can straighten the taper and get them round with a good hone. I'm not talking dingle berry hone or cheap straight stone hone. How much do you think they leave after a bore to hone the final size and finish in a cylinder? Nothing wrong with new pistons, bore and hone. It is just time and money and yes, you should have a tighter fit. But I'm here to tell you I have, and have built engines for others, that run out fine with a short block that had .004 to .005 clearance, reusing pistons, and Speed Pro file to fit rings. I have three such short blocks I will be rebuilding this way. A 273, a 340 and a 318 magnum because they each have such little wear in the block. My engines have plenty of power and have yet to have one not run very good or last at least 200,000 miles. As a matter of fact, I've never had one die. I usually am swapping engines because I want to try something else or gas octane took a nose dive and I had to lower compression.

I'm not arguing against honning per se. Just don't agree with trying to hone several thousanths. Most of my engines are stock bore 100,000 engine, with a hone and re ring, and a plain cast ring. They don't push oil, and make good power, both with nitrous and/or turbo. But will they last 50-60 thousands miles? I doubt it.
PS: Are you talking about a Sunnen power hone, or the hand held Sunnen hone with the dial, that is used with a drill? I have the second type, and that would take a lot of time, and use up the stones, trying to take out more then about 1 thousanth.

 

[66fs]

I'm not arguing against honning per se. Just don't agree with trying to hone several thousanths. Most of my engines are stock bore 100,000 engine, with a hone and re ring, and a plain cast ring. They don't push oil, and make good power, both with nitrous and/or turbo. But will they last 50-60 thousands miles? I doubt it.
PS: Are you talking about a Sunnen power hone, or the hand held Sunnen hone with the dial, that is used with a drill? I have the second type, and that would take a lot of time, and use up the stones, trying to take out more then about 1 thousanth.

I also have the hand held Sunnen AN hone for use with a 3/4" slow drill. Not for the weak or faint of heart. I use more than a few different grades of stones when I did that work. The hone will certainly do more than a thousandth cleanly. You should have seen some "rebuilt" Chevrolet blocks I fixed. Some were bored without torquing the main caps so there was an interference fit at the bottom of the cylinder by more than a couple thousandths, let alone not being round at the top. Funny thing, those engines were down on power and ran hot. If doing what I suggest, you cherry pick your block by measuring the wear, not many will pass the grade. Chrysler made very good pistons, so they usually wear very little. I always ran Speed Pro file to fit rings with ductile iron top rings. If you are running a high performance engine why cheap out on rings? The ony point I was trying to make is if you are carefull and have a good block you don't need to do a full up rebuild. My "cheapo rebuilds would run better and longer than a lot of "new piston" rebored engines someone else did. I don't use any power adders and run on the street, but I need a car that can run all day long at 75 to 100 mph with zero problems ever. Think upper midwest.

 

[RAMM]

With a true rigid hone like a Sunnen CK-10 there is absolutely no problem honing cylinders oversize. I've often honed blocks .030" O.S.

To answer the OP's question-I doubt your bore will clean up. There will be non-cleanup and then it will be a judgement call as to whether it is acceptable to leave it or not. J.Rob

 

[CFD244]

With a true rigid hone like a Sunnen CK-10 there is absolutely no problem honing cylinders oversize. I've often honed blocks .030" O.S.

To answer the OP's question-I doubt your bore will clean up. There will be non-cleanup and then it will be a judgement call as to whether it is acceptable to leave it or not. J.Rob

So in your opinion, with these measurements, .030 over on this block would be a no go? I didn't want to go .040 on my numbers block. Looks like it will be living on the stand waiting for the next guy to decide what to do.

 

[RAMM]

.030" O.S. is a go. I'd go .060" to 4.100" if I had to. No problem with that. J.Rob

 

[gzig5]

What's the difference if it's .030 or .040 over? That is literally the thickness of a piece of paper in the cylinder wall and won't make a difference in the life of the motor.

 

[CFD244]

What's the difference if it's .030 or .040 over? That is literally the thickness of a piece of paper in the cylinder wall and won't make a difference in the life of the motor.

I suppose. I just consider .040 the last step before sleeving. Trying to keep it as original as possible. .030 gives me some breathing room. I don't care about the other 340 that I have. It's freshly bored to .040 with one sleeve. and that's probably the one going in. I'll keep the numbers engine as a museum piece. I'll leave it "worn out" and just store it on my run stand to fire up every 3 months or so to keep things clean and moving.

 

[Inertia]

I suppose. I just consider .040 the last step before sleeving. Trying to keep it as original as possible. .030 gives me some breathing room. I don't care about the other 340 that I have. It's freshly bored to .040 with one sleeve. and that's probably the one going in. I'll keep the numbers engine as a museum piece. I'll leave it "worn out" and just store it on my run stand to fire up every 3 months or so to keep things clean and moving.

I wouldn't have a number matching car if I hadn't sleeved a total of 3 cyls over time.
I ran 12.5 pistons 060 over and ran 2/10 off nhra record .
Still driving car today, pistons trimmed 3 times, down to 10 1/2 now .
Piston manufacturers wouldn't tool up to make .060 pistons if there wasn't a huge market ! !