4 axis knows what you want to do before you do it....or was that the 5th.....
Used for contouring and doing work on a cylindrical shape while moving around the piece! 3D in a circle so to speak.....
Apparently there are 5 axis systems too....!!!
Crazy tools!!!!
This is about saving a block for street use. If you're trying for 500+ bhp or high rpms, this post is irrelevant. One should understand that most bore wear is at the extreme top of the cylinder. That area gets no oil, is above the ring contact area and does NOT need to be flawless. All it needs is enough of the wear-step tapered so you don't break ring lands when removing/replacing the pistons. That's why I typically HONE cylinders that are not badly damaged, rather than boring. Even minor pits left after honing are not cause for scrapping (or boring) a block.
Forged 2618-alloy pistons expand when hot & running, so they can accommodate up to about 0.005" of oversize: e.g- a 4.005" cylinder can use a 4.000" 2618-forged piston but NOT a cast/hypereutectic. Such mismatches will rattle on startup but quiet down within seconds. Forged alloy 4032 has quite a bit of silicon in it which makes those pistons not expand as much with heat, and are more brittle. They won't tolerate 0.005" oversize bores without cracking.
As far as sleeving, one cylinder on each bank will work fine. More than that is iffy for high horsepower. The weak spot in a stock block is at the bottom of the cylinders where the bores get close to the main bearing saddles. That area is weakened even more in the huge overboring needed to add sleeves. Good luck.
Forged 2618-alloy pistons expand when hot & running, so they can accommodate up to about 0.005" of oversize: e.g- a 4.005" cylinder can use a 4.000" 2618-forged piston but NOT a cast/hypereutectic. Such mismatches will rattle on startup but quiet down within seconds. Forged alloy 4032 has quite a bit of silicon in it which makes those pistons not expand as much with heat, and are more brittle. They won't tolerate 0.005" oversize bores without cracking.
As far as sleeving, one cylinder on each bank will work fine. More than that is iffy for high horsepower. The weak spot in a stock block is at the bottom of the cylinders where the bores get close to the main bearing saddles. That area is weakened even more in the huge overboring needed to add sleeves. Good luck.
Dry sleeves shouldn't be a problem, never heard of a block with them installed failing, I think it prudent to limit any engine with a production block to 450 bhp, 7200 rpm, 8.0:1 dynamic compression ... especially those with sleeves. Keep in mind that a poorly tuned engine will beat on a reciprocating assembly and its support structure worse than anything else.
Example, a former member of the forums did a tune-up on his Pantera's engine. His son installed a new set of plug wires, and crossed a pair of wires. When they started the engine it was running roughly, so the owner took the car out on the road and "floored it" thinking the engine just needed to be "blown out". Well, he blew crank through the oil pan, and left it laying on the road behind the car.
We used to tell people the stock block was OK to 500 bhp, but now that a new heavy duty block is available from T.Meyer Inc, I prefer the lower limit. Anyone wanting to build an engine producing over 450 bhp, revving over 7200 rpm, or with more than 8.0:1 dynamic compression should use the heavy duty block as a foundation. That is what the Buttermore block endeavor (that Tim has brought to fruition) was all about.
Example, a former member of the forums did a tune-up on his Pantera's engine. His son installed a new set of plug wires, and crossed a pair of wires. When they started the engine it was running roughly, so the owner took the car out on the road and "floored it" thinking the engine just needed to be "blown out". Well, he blew crank through the oil pan, and left it laying on the road behind the car.
We used to tell people the stock block was OK to 500 bhp, but now that a new heavy duty block is available from T.Meyer Inc, I prefer the lower limit. Anyone wanting to build an engine producing over 450 bhp, revving over 7200 rpm, or with more than 8.0:1 dynamic compression should use the heavy duty block as a foundation. That is what the Buttermore block endeavor (that Tim has brought to fruition) was all about.
quote:Originally posted by George P:
Dry sleeves shouldn't be a problem, never heard of a block with them installed failing, I think it prudent to limit any engine with a production block to 450 bhp, 7200 rpm, 8.0:1 dynamic compression ... especially those with sleeves. Keep in mind that a poorly tuned engine will beat on a reciprocating assembly and its support structure worse than anything else.
Example, a former member of the forums did a tune-up on his Pantera's engine. His son installed a new set of plug wires, and crossed a pair of wires. When they started the engine it was running roughly, so the owner took the car out on the road and "floored it" thinking the engine just needed to be "blown out". Well, he blew crank through the oil pan, and left it laying on the road behind the car.
We used to tell people the stock block was OK to 500 bhp, but now that a new heavy duty block is available from T.Meyer Inc, I prefer the lower limit. Anyone wanting to build an engine producing over 450 bhp, revving over 7200 rpm, or with more than 8.0:1 dynamic compression should use the heavy duty block as a foundation. That is what the Buttermore block endeavor (that Tim has brought to fruition) was all about.
+1.
I agree completely with George. Remember also that stock diameter fuel lines in the tank & sender will ALSO only support about 450 real horses, if a carburetor and high rpms are used. Typically, big horsepower only happens above 6000 rpms so when you run lean up high on the tach, your most useful tool may be a broom to clean up the mess!
Multiport EFI runs at 6-8X the pressure of a carb, which then flows a little more fuel thru still-smaller-than-desired stock steel fuel lines. Adding big lines only from pump to carb does approximately nothing to increase high rpm fuel flow. You're still sucking from the tank thru a small straw...
Multiport EFI runs at 6-8X the pressure of a carb, which then flows a little more fuel thru still-smaller-than-desired stock steel fuel lines. Adding big lines only from pump to carb does approximately nothing to increase high rpm fuel flow. You're still sucking from the tank thru a small straw...
quote:Originally posted by Bosswrench:
This is about saving a block for street use. If you're trying for 500+ bhp or high rpms, this post is irrelevant. One should understand that most bore wear is at the extreme top of the cylinder. That area gets no oil, is above the ring contact area and does NOT need to be flawless. All it needs is enough of the wear-step tapered so you don't break ring lands when removing/replacing the pistons. That's why I typically HONE cylinders that are not badly damaged, rather than boring. Even minor pits left after honing are not cause for scrapping (or boring) a block.
Forged 2618-alloy pistons expand when hot & running, so they can accommodate up to about 0.005" of oversize: e.g- a 4.005" cylinder can use a 4.000" 2618-forged piston but NOT a cast/hypereutectic. Such mismatches will rattle on startup but quiet down within seconds. Forged alloy 4032 has quite a bit of silicon in it which makes those pistons not expand as much with heat, and are more brittle. They won't tolerate 0.005" oversize bores without cracking.
As far as sleeving, one cylinder on each bank will work fine. More than that is iffy for high horsepower. The weak spot in a stock block is at the bottom of the cylinders where the bores get close to the main bearing saddles. That area is weakened even more in the huge overboring needed to add sleeves. Good luck.
Is a simple honing of a few thousandths made with a pressure plate able to eliminate ovalization and barrel shape?
Usually not economical to hone more than about 0.004" (0.001" or .002" is usual), because of the time & labor invested- honing is slow. It's also easy to build a taper into a deep-honed cylinder if you're doing it by hand. And more than about 0.004" removed by any means usually calls for new forged pistons (2618 alloy which expands more with heat).
So if you have a cylinder or two that has more problems than 0.004" can fix, you should have your shop bore the engine, or find a different block. And if you bore, you should first sonic-check the cylinder wall thicknesses- many shops can offset the boring machine to partially compensate for a cylinder that is thin on one side. Std gaskets will allow this slight misalignment with no problems.
If bored, you will then need new pistons and today, custom sizes are available for not much extra. You are NOT stuck with the usual std or 0.030"-over off-the-shelf pistons; either cast-hypoeutectic or forged can be made. This can be a lifesaver for scarce 351-C thin-wall blocks.
If you have more time than money and are doing the engine yourself sort of as a hobby, you can hone out more than 0.004" but it will take days to do eight cylinders. I also suggest sonic-checking the cylinder walls just for your own information, even though with hand-honing you will not be able to compensate.
You are right on mentioning the torque plate; many years ago, I wrote an article on how much a typical thin-wall 351-C changes bore measurements with and without a plate torqued on. Before honing or boring, I suggest adding a torque plate and re-checking for cylinder problems. On several cylinders in the article, the bore changed in one direction, while one cylinder changed the opposite way. The biggest change was around 0.002". So if your block was prepped WITH a torque plate and its bores are later checked without it, the block may show distortions or ovality that will disappear once the heads are torqued on.
As an added note, precision engine builders are now using torque plates on iron 351-C CYLINDER HEADS before doing a valve job. OEM cylinder heads were cast thin-wall, too....
So if you have a cylinder or two that has more problems than 0.004" can fix, you should have your shop bore the engine, or find a different block. And if you bore, you should first sonic-check the cylinder wall thicknesses- many shops can offset the boring machine to partially compensate for a cylinder that is thin on one side. Std gaskets will allow this slight misalignment with no problems.
If bored, you will then need new pistons and today, custom sizes are available for not much extra. You are NOT stuck with the usual std or 0.030"-over off-the-shelf pistons; either cast-hypoeutectic or forged can be made. This can be a lifesaver for scarce 351-C thin-wall blocks.
If you have more time than money and are doing the engine yourself sort of as a hobby, you can hone out more than 0.004" but it will take days to do eight cylinders. I also suggest sonic-checking the cylinder walls just for your own information, even though with hand-honing you will not be able to compensate.
You are right on mentioning the torque plate; many years ago, I wrote an article on how much a typical thin-wall 351-C changes bore measurements with and without a plate torqued on. Before honing or boring, I suggest adding a torque plate and re-checking for cylinder problems. On several cylinders in the article, the bore changed in one direction, while one cylinder changed the opposite way. The biggest change was around 0.002". So if your block was prepped WITH a torque plate and its bores are later checked without it, the block may show distortions or ovality that will disappear once the heads are torqued on.
As an added note, precision engine builders are now using torque plates on iron 351-C CYLINDER HEADS before doing a valve job. OEM cylinder heads were cast thin-wall, too....
Thank you for this answer, but my question was about the geometrical shape, when they are worn the cylinders are no longer cylindrical, they are oval and barrel-shaped, the area where the piston presses towards the mid-height is more worn than the top and the bottom. I wanted to know if a simple honing done at a machinist, not done by himself with a tool to a few dollars, catches these defects of geometric shape.