Engine smoking badly after rebuild... HELP PLEASE!...
Discussion
Still quite a lot of piston skirt scuffing but at least no unusual marks from the oil rings. Might be worth comparing the ring gaps on both oil rings to make sure the other set weren't too tight and butting together when they got hot. However it's still most likely to be mainly down to the honing IMO.
Oil controll ring gap was 0.5mms at the start and the oil scraper ring (2nd compression ring) gap was 0.3mms. Now they are 0.6mms and 0.35-0.4mms. The bores wore 0.015mms in average (!).
I have dismantled the engine and reasembled it with an old A+ block using the "new" pistons and rings. Although the piston-bore clearance is very big (0.1mms). I will put it in tomorow to see if it makes any difference.
I have dismantled the engine and reasembled it with an old A+ block using the "new" pistons and rings. Although the piston-bore clearance is very big (0.1mms). I will put it in tomorow to see if it makes any difference.
Edited by camelotr on Monday 10th May 20:52
Edited by camelotr on Monday 10th May 21:47
I should add to my above comments about the bore picture above that again you can clearly see all the horizontal marks under the cross hatching. In this case you can also see in the shiny area where the piston skirt has worn the bore that the horizontal marks are like dashed lines - - - -. This is very characteristic of what you see as you start to hone a freshly bored block. The boring marks, especially from old or flimsy boring bars with play in them, have some "chatter" so as the honing removes the boring marks you first get left with these dashed lines leaving the deeper bits of chatter showing through until you've honed more out.
This is conclusive that very little stock was removed by the honing. The cylinder was bored almost to final size and then just lightly honed over the top to make it look like a proper job.
Terrible, terrible workmanship. The worst I have seen in 30 years. If these people are working on Porsches and the like then god knows how those run once they've finished.
Obviously at a very minimum the boring must be done leaving enough stock in place so that the honing removes all trace of the boring marks. There is also opinion that even this is not enough, that even when all visible traces of the boring marks have gone there is still some "disturbance" to the structure of the cast iron underneath as a result of the cutting forces of the boring tool. This is why a common recommendation is to leave 0.003" of stock for honing even though with a good boring bar the boring marks would all be visibly removed long before then. Personally I think 0.002" (0.001" on radius) is plenty and that with a good boring bar and correctly sharpened tool you don't get boring marks anything like 0.001" deep.
Finally, even with this terrible boring and honing there is less wear on this block than the linered one so I'm wondering if the quality of the liners used was not good and the metal is too soft or the wrong grade of cast iron. Another reason not to waste money linering old A series blocks anyway.
This is conclusive that very little stock was removed by the honing. The cylinder was bored almost to final size and then just lightly honed over the top to make it look like a proper job.
Terrible, terrible workmanship. The worst I have seen in 30 years. If these people are working on Porsches and the like then god knows how those run once they've finished.
Obviously at a very minimum the boring must be done leaving enough stock in place so that the honing removes all trace of the boring marks. There is also opinion that even this is not enough, that even when all visible traces of the boring marks have gone there is still some "disturbance" to the structure of the cast iron underneath as a result of the cutting forces of the boring tool. This is why a common recommendation is to leave 0.003" of stock for honing even though with a good boring bar the boring marks would all be visibly removed long before then. Personally I think 0.002" (0.001" on radius) is plenty and that with a good boring bar and correctly sharpened tool you don't get boring marks anything like 0.001" deep.
Finally, even with this terrible boring and honing there is less wear on this block than the linered one so I'm wondering if the quality of the liners used was not good and the metal is too soft or the wrong grade of cast iron. Another reason not to waste money linering old A series blocks anyway.
Edited by Pumaracing on Tuesday 11th May 05:01
I have a very unpleasent experience with 2nd party jobs. Be it an upholsterer, a panel beater or chrom plater. If You do not take close controll on them, they do trash-job. Thats why I try to learn as much as I can to be at least able to judge a job or to be able to give close instructions on the "howto".
If only I could do at least the honing myself...
If I am right, the (proper) honing takes more time then the boring?
About linering the A-series. Unfortunatly pre-A+ 1275 blocks are getting rare. Many of them have been rebored to their final oversizes soo there is not to much to do. Especialy You can imagine how rare they can be in Hungary. And postage form Englan... well...
If only I could do at least the honing myself...
If I am right, the (proper) honing takes more time then the boring?
About linering the A-series. Unfortunatly pre-A+ 1275 blocks are getting rare. Many of them have been rebored to their final oversizes soo there is not to much to do. Especialy You can imagine how rare they can be in Hungary. And postage form Englan... well...
stevieturbo said:
If the bore itself was sound.
Would a cordless drill and ball flex hone not suffice ?
It's worked for me plenty of times with no problems.
It may be Ok for glaze busting a bore that has previously been machined correctly and is being re-ringed but is an absolute no-no in a freshly bored cylinder.Would a cordless drill and ball flex hone not suffice ?
It's worked for me plenty of times with no problems.
There is no way of ensuring that either the desirable geometry or sizing are arrived at if a flex hone is used in this case .
stevieturbo said:
If the bore itself was sound.
Would a cordless drill and ball flex hone not suffice ?
It's worked for me plenty of times with no problems.
Lawks no. Not in a month of Sundays. A flexhone can remove a tenth of a thou or so but all it does is condition the surface and plateau hone whatever is already there. A proper hone is needed to remove thousandths of an inch, achieve perfect roundness, remove boring tool marks and cross hatch the surface.Would a cordless drill and ball flex hone not suffice ?
It's worked for me plenty of times with no problems.
Those spring loaded toy hones with three legs are a waste of space too apart from tickling up old bores for new rings.
A proper hone with micrometer adjustment puts an enormous load on the stones and needs huge torque to drive it. Maybe 40 ft lbs or more if you have the right drill. My little drill can maybe achieve 10 ft lbs and does shift the metal eventually and if I was doing a lot of this work would be replaced with something bigger.
camelotr said:
If only I could do at least the honing myself...
If you could find a second hand Delapena hone and a big drill there's no reason why you can't. It isn't that expensive to set up for boring either. A second hand Van Norman boring bar or similar can usually be picked up from machinery dealers. Delapena themselves in the UK sell second hand stuff. Might be worth trying them and I have some special contacts myself if you are really interested.So I managed to reassemble the engine and put it in situ. Although the piston-bore clearance is 0.1mms, the damn steel is not smoking a bit!!! I have only done about 20kms, but on this way the plugs and the end of the exhaust all cleaned up.
Is there any other reason for this other then the original block was badly bored/honed? I am realy courious.
Is there any other reason for this other then the original block was badly bored/honed? I am realy courious.
You've been a busy boy. An engine rebuild and swap could take me a month.
Haven't you answered your own question by swapping just the block?
At least you now know why honing is so important and why I used to go to such lengths trying to achieve perfection in it.
Common sense tells us that even though the pistons are not ideal in crown diameter and it's possible to raise speculation about the ring packs it's incredibly rare to find serious design faults in either of these areas in OE items so the bore finish, and possibly the liner material, are all that's really left to explain engine smoking.
Now you also know why I was getting so cross about the pictures of those idiot's bore honing. Basically the ring packs have just been bouncing up and down over their crap workmanship, shagging themselves and the bores in the process and passing lots of oil into the combustion chambers.
Go back and re-read my very first post in this thread. I could have saved a lot of typing by stopping right there because everything you needed to know was already said.
Haven't you answered your own question by swapping just the block?
At least you now know why honing is so important and why I used to go to such lengths trying to achieve perfection in it.
Common sense tells us that even though the pistons are not ideal in crown diameter and it's possible to raise speculation about the ring packs it's incredibly rare to find serious design faults in either of these areas in OE items so the bore finish, and possibly the liner material, are all that's really left to explain engine smoking.
Now you also know why I was getting so cross about the pictures of those idiot's bore honing. Basically the ring packs have just been bouncing up and down over their crap workmanship, shagging themselves and the bores in the process and passing lots of oil into the combustion chambers.
Go back and re-read my very first post in this thread. I could have saved a lot of typing by stopping right there because everything you needed to know was already said.
Edited by Pumaracing on Tuesday 11th May 17:24
You were quite all right from the beginning. Unfortunatly I am a man who first thinks that he is bad and is searching the problem within his own work, and trust the machinist all to long 
.
Anyway without You invaluable halp, I could not make that far. THANKS!
Although I will settle only when the engine will be rebored and it will perfom well. I will report.
Unfortunatly I have to start this engine again from 0...
For everybody else: learn from my bad story...
.Anyway without You invaluable halp, I could not make that far. THANKS!
Although I will settle only when the engine will be rebored and it will perfom well. I will report.
Unfortunatly I have to start this engine again from 0...
For everybody else: learn from my bad story...
There's a lot of nonsense talked about under the general heading of "blueprinting" which people seem to think is about such things as bearing clearances and getting every machining datum true to the crank centreline within microns. In my long experience the only thing in the bottom end that really affects power and reliability is the bore finish. You can fret endlessly about whether a race engine should have an extra half thou bearing clearance, how finely polished the crank journals should be, whether to use 2 thou or 3 thou piston clearance but the engine won't really give a damn one way or the other as long as you don't do something really stupid.
Get the bore finish wrong though and you're dead in the water. If there's ANY horizontal component remaining of either the boring operation or produced later by faulty honing then the rings don't stand a chance and proper lubrication won't take place. The cross hatch is essential to retain oil and let the piston skirts float on a cushion of it without making metal to metal contact until the bore is bedded in and glazed over. Once the rings are bedded in the cross hatch is less important and in fact the cross hatch pattern eventually fills up with glaze created by by-products of combustion until the bore is completely smooth.
However horizontal marks don't trap oil, they let the piston rings scoop oil over them on both up and down strokes so you get a constant flow of oil going into the chambers, burning and then some of it coming back down. They also don't let the piston skirts float over the bore surface. To give an idea of how much power this can cost I saw what happened when someone else, supposedly a professional company, rebuilt one of my Fiesta race engines because the guy who bought the car didn't know who had originally done the engine. I know what happened because after the engine finally blew up he found out who to go to and I got it back to inspect.
This company didn't really change any of my cylinder head work or change any other parts because the rules required all components to be standard but they did "hone" the bores before fitting new rings. They did this with one of those crappy glaze buster things but were too witless to realise you also have to move them up and down to create a cross hatch. They did the whole thing with the hone stationary and filled all the bores with horizontal scratches. The engine lost 10 of its original 88 bhp at the wheels on the same rolling road and later in the season the block cracked open and had to be scrapped. When I got the engine back to recover the cylinder head and other good bits the bare bottom end, despite nearly a season's running, took 30 ft lbs to turn over on the crank pulley nut when a properly run in bottom end would spin almost freely. You could even hear the rings graunching over the bore surface. You could also hear my jaw drop when I saw what they'd done to my lovely bore work.
So that's over 10% power loss from the extra friction and poor ring sealing just by cocking the bore finish up.
That's also why proper honing equipment was one of the first things I bought long before I ever had my own boring bar. Even when I had to farm out the boring I'd give them a size to work to of half a thou under final size so I could finish things off myself to get my own preferred surface finish and correct any taper or ovality they might have created.
Get the bore finish wrong though and you're dead in the water. If there's ANY horizontal component remaining of either the boring operation or produced later by faulty honing then the rings don't stand a chance and proper lubrication won't take place. The cross hatch is essential to retain oil and let the piston skirts float on a cushion of it without making metal to metal contact until the bore is bedded in and glazed over. Once the rings are bedded in the cross hatch is less important and in fact the cross hatch pattern eventually fills up with glaze created by by-products of combustion until the bore is completely smooth.
However horizontal marks don't trap oil, they let the piston rings scoop oil over them on both up and down strokes so you get a constant flow of oil going into the chambers, burning and then some of it coming back down. They also don't let the piston skirts float over the bore surface. To give an idea of how much power this can cost I saw what happened when someone else, supposedly a professional company, rebuilt one of my Fiesta race engines because the guy who bought the car didn't know who had originally done the engine. I know what happened because after the engine finally blew up he found out who to go to and I got it back to inspect.
This company didn't really change any of my cylinder head work or change any other parts because the rules required all components to be standard but they did "hone" the bores before fitting new rings. They did this with one of those crappy glaze buster things but were too witless to realise you also have to move them up and down to create a cross hatch. They did the whole thing with the hone stationary and filled all the bores with horizontal scratches. The engine lost 10 of its original 88 bhp at the wheels on the same rolling road and later in the season the block cracked open and had to be scrapped. When I got the engine back to recover the cylinder head and other good bits the bare bottom end, despite nearly a season's running, took 30 ft lbs to turn over on the crank pulley nut when a properly run in bottom end would spin almost freely. You could even hear the rings graunching over the bore surface. You could also hear my jaw drop when I saw what they'd done to my lovely bore work.
So that's over 10% power loss from the extra friction and poor ring sealing just by cocking the bore finish up.
That's also why proper honing equipment was one of the first things I bought long before I ever had my own boring bar. Even when I had to farm out the boring I'd give them a size to work to of half a thou under final size so I could finish things off myself to get my own preferred surface finish and correct any taper or ovality they might have created.
I've just found this online.
http://www1.shopping.com/xPO-Lisle_Lisle_Engine_Cy...
I can see that's an exact copy of the Snap-On Blue Point CFL10 which was the first honing system I bought. The only minor bad point about it is the 5" long stones which means you can't get quite as much up and down movement as the Delapena with 4" stones but it did many blocks for me with great accuracy and still gets used from time to time. At that price it's a steal. I think I paid £300 for my Snap-On and that was 20 years ago.
With long stones it's harder to get the bottom of the bores up to size without keeping on taking more out of the top of the bores. It's a cast iron certainty when hand honing that you always end up with the top of the bores a bit bigger than the bottoms although with brand new stones this is less of an issue. That's why you learn to hone just the bottom of the bores first and then work further up. One trick is to cut a set of stones down with a hacksaw so only the bottom 3" remain and use those just for sizing the bottom of bores. Yes you can cut honing stones with a hacksaw. You'd think they'd just grind the saw down but no.
http://www1.shopping.com/xPO-Lisle_Lisle_Engine_Cy...
I can see that's an exact copy of the Snap-On Blue Point CFL10 which was the first honing system I bought. The only minor bad point about it is the 5" long stones which means you can't get quite as much up and down movement as the Delapena with 4" stones but it did many blocks for me with great accuracy and still gets used from time to time. At that price it's a steal. I think I paid £300 for my Snap-On and that was 20 years ago.
With long stones it's harder to get the bottom of the bores up to size without keeping on taking more out of the top of the bores. It's a cast iron certainty when hand honing that you always end up with the top of the bores a bit bigger than the bottoms although with brand new stones this is less of an issue. That's why you learn to hone just the bottom of the bores first and then work further up. One trick is to cut a set of stones down with a hacksaw so only the bottom 3" remain and use those just for sizing the bottom of bores. Yes you can cut honing stones with a hacksaw. You'd think they'd just grind the saw down but no.
Update.
I have dismantled this "test engine" (old block with the "new pistons"). I have found the pistons to be oily. This was a very embrassing find as the engine was working perfectly without any hint of oil burning. The plugs were looking fine, and the end of the exhaust was dry.
I have also exemined the exhaust manifold, and it was also dry.
I am confused again...
I have dismantled this "test engine" (old block with the "new pistons"). I have found the pistons to be oily. This was a very embrassing find as the engine was working perfectly without any hint of oil burning. The plugs were looking fine, and the end of the exhaust was dry.
I have also exemined the exhaust manifold, and it was also dry.
I am confused again...
I take it that's the oil ring groove I'm looking at? If the oil ring rotates freely in its groove and doesn't bottom out in it so it can compress normally then it should operate ok. Also why would badly machined grooves in the AE pistons cause the Mini Spares ones to burn oil too? Sympathetic magic?
Anyway it warrants sending the pistons back for a refund and then maybe you can start again with better pistons and better machining.
I do have to say that quality control of AE products has gone right down the toilet in the last few years. I've also seen poorly made valves and valve seat inserts on too many occasions now.
It's been mentioned before but make absolutely sure you have free flowing breather pipes from the sump so it cannot possibly get pressurised down there. I think you said you'd tried feeding the pipes into a catch tank but again be sure there is a big enough exit from that tank at least as large in area as all the pipes feeding in to it.
Anyway it warrants sending the pistons back for a refund and then maybe you can start again with better pistons and better machining.
I do have to say that quality control of AE products has gone right down the toilet in the last few years. I've also seen poorly made valves and valve seat inserts on too many occasions now.
It's been mentioned before but make absolutely sure you have free flowing breather pipes from the sump so it cannot possibly get pressurised down there. I think you said you'd tried feeding the pipes into a catch tank but again be sure there is a big enough exit from that tank at least as large in area as all the pipes feeding in to it.
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