My buddy wants to render a cylinder useless on his 64 Caddy's 429. The compression is poor and he thinks a ring is broken or the cylinder wall is very scored. It smokes alot and uses alot of oil, his compression on the other 7 cylinders is good. His thought is to block fuel from entering the cylinder by removing the rocker on the intake valve so it stays shut. But the piston will still go up and down of course so he was thinking somehow hold the exhaust valve partly open at all times? Is he thinking right about this? Is there a more effective way? Obviously the piston could be replaced, or the cylinder wall honed, but any ideas on how to disable the cylinder? The lifters in this car are hydraulic, if that makes any difference.
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11:48 PM
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spark1 Member
Posts: 11159 From: Benton County, OR Registered: Dec 2002
My buddy wants to render a cylinder useless on his 64 Caddy's 429. The compression is poor and he thinks a ring is broken or the cylinder wall is very scored. It smokes alot and uses alot of oil, his compression on the other 7 cylinders is good. His thought is to block fuel from entering the cylinder by removing the rocker on the intake valve so it stays shut. But the piston will still go up and down of course so he was thinking somehow hold the exhaust valve partly open at all times? Is he thinking right about this? Is there a more effective way? Obviously the piston could be replaced, or the cylinder wall honed, but any ideas on how to disable the cylinder? The lifters in this car are hydraulic, if that makes any difference.
4 at a time in the LS4 Not a good idea otherwise.
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11:58 PM
MidEngineManiac Member
Posts: 29566 From: Some unacceptable view Registered: Feb 2007
A 1976 Lotus twin-cam 4 will run and drive on one firing.....'course, there aint no power, and it backfires like hell (eeyyyy, yeh, twin 54 webber sidedrafts instead of stromburgs might have something to do with that). Fire might even be in the equation.
But Yeh..
Ya can drive a car with less than optimal cylanders.....
If you remove the intake rocker, what's keeping the lifter in the bore? And if its not in its bore, where does the oil, and oil pressure, go? AFAIK, there's an oil supply to the lifter bore. Leave it wide open, and you'll lose oil pressure.
As for exhaust, cranking down on the rocker till the exhaust valve hangs open would do the trick, but I thought Caddy valvegear was non-adjustable? Anyway, with the exhaust valve open, the oil sloshing around in that cylinder will still find its way out the exhaust.
Regardless, disabling a cylinder that's still firing, even poorly, will make an engine run even worse. If you've holed a piston, and are trying to make it home, or to a shop, give it a try. But in your friend's case, I can't see how it'll help.
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12:29 AM
Raydar Member
Posts: 41183 From: Carrollton GA. Out in the... country. Registered: Oct 1999
I believe that the LS4 disables both valves on the cylinders that it "drops". Doing it on one cylinder will probably be ugly, but it shouldn't hurt anything.
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12:31 AM
2.5 Member
Posts: 43235 From: Southern MN Registered: May 2007
I believe that the LS4 disables both valves on the cylinders that it "drops". Doing it on one cylinder will probably be ugly, but it shouldn't hurt anything.
When you say drops does that mean they stay shut? If this happens wouldnt it create a sort of airlock as the piston tries to move?
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01:58 AM
CowsPatoot Member
Posts: 2792 From: Skidway Lake, MI Registered: May 2007
When you say drops does that mean they stay shut? If this happens wouldnt it create a sort of airlock as the piston tries to move?
It would build compression as the piston goes up....but that pressure would help push it back down. Across 4 cylinders even in the firing order, they would cancel each other out.
Obviously you would have to lock the intake valve closed or you would also have unburned gas running through the cylinder...NOT a good idea (if it were MPFI, then you could disable the injector too). But...if you locked the exhaust open, then it would pull exhaust from the other cylinders in that bank IN during each downstroke. Can't imagine what that is going to do to the exhaust flow on that side.
Maybe it time to break down and rebuild it....would you really want to cruise around in a car that is running that rough?
I would think you would not want any compression at all in that cylinder so I would think the best route would be to remove the exhaust valve totally and "seal" the intake shut. ( of course you cant do that without opening it up, unless perhaps its a non-interference engine i guess and block it open? )
Still going to lose oil in there if the rings are bad.. but now its going to come out un-burnt..
But like the others have said, it just sounds like a bad idea unless its a 'please get me home without walking' thing.. ( knowing you may ruin the engine in the process )
[This message has been edited by User00013170 (edited 02-16-2013).]
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09:09 AM
fierofool Member
Posts: 12960 From: Auburn, Georgia USA Registered: Jan 2002
The cylinder must breathe in some manner. Holding valves open will cause it to mix exhaust and intake gases. One valve open will cause it to pull and push gases to that side of the system. Raw gas from the intake would wash the cylinder walls.
In high school during the late 50's/early 50's I had a classmate who owned a 40's something Kaiser Frazer with a flat head inline 6. It was knocking pretty badly, so he removed the oil plan and head, removed 3 pistons and rods so that the crank was still balanced. He drove it for several years until he graduated. It had a very strange exhaust note as there was a slight pause between the firing of 2 cylinders then the 3rd one firing. Something like the rhythm of a horse galloping.
So, if you disable so as to keep the forces on the crankshaft equally spaced, it might work out well.
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09:25 AM
84fiero123 Member
Posts: 29950 From: farmington, maine usa Registered: Oct 2004
Caddy had a V8/6/4 back in the 80’s, never got too much info on it other than they disabled pairs of pistons to balance the engine while it was running on 6/4 cylinders. Disabling one piston I would think would make the engine run rough and not be good for it.
Even with just one bad piston burning oil, if that is all he is worried about would make even more problems for him. Just ether run it the way it is. Pull the plug wire on the cylinder so it doesn’t burn the oil or rebuild the engine, at least pull head on the offending cylinder, replace the oil ring, and hone the wall a little. (if that is even possible to do without pulling the pan, not sure, haven’t had but a half a cup of coffee)
There is no simple answer to that.
Now I have had big engines like that in an old caddy burn oil, so what it burns a little oil. Those old caddies would run forever even with all the cylinders burning oil, I had one I had that I bought for 75 bucks years ago, well actually decades ago that ran for a very, very, very long time for me and the only reason I got rid of it was the rear frame was so bad you couldn’t jack the rear end up. ‘’drive the dam thing or rebuild it.
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
Detroit iron rules all the rest are just toys.
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09:32 AM
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rogergarrison Member
Posts: 49601 From: A Western Caribbean Island/ Columbus, Ohio Registered: Apr 99
I drove a V8 for months, even on 100 mile trips, that burned a quart of oil every 25 miles. I just bought cases of bulk motor oil and kept it in the trunk. Maybe just loosen that cyl spark plug enough to keep oil from coming out, but preventing any compression.
Did this once to an Olds 371 from 59. Just pulled both push rods, didn't even mess with the lifter. It stayed in the high side of it's hole, I guess because it got slapped up a bit higher than it normally ran, putting it in a stuck mode just off the cam. It probably could have just as easily popped up into the lifter valley and just laid there. Drove it for months when I had no money to do otherwise.
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05:01 PM
Old Lar Member
Posts: 13798 From: Palm Bay, Florida Registered: Nov 1999
I heard the story from an old gearhead who removed the piston so the car just ran on seven. This was a 1950s Ford and the car ran great, they sold it like that, the girls who bought it drove it the California, sold it out there. The girls came back through and said that the car ran great, got good gas mileage and wondered if they had another good car around.
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09:55 PM
Feb 17th, 2013
rogergarrison Member
Posts: 49601 From: A Western Caribbean Island/ Columbus, Ohio Registered: Apr 99
I knew a guy who was driving across NM in the 60s in a straight 8 Buick. It threw a rod and only had internal damage. They pulled the pan, took out the broken rod and drove it the rest of the way to Calif.
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04:26 PM
tebailey Member
Posts: 2622 From: Bay City MI Registered: Jan 2013
If it's worn out bad enough to be sucking oil, the lifters on that cyl are more than likely mushroomed out enough that they won't pop out into the lifter galley. Just pull the rockers and pushrods. We drove a 57 Chevy like that for 2yrs.
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08:24 PM
2.5 Member
Posts: 43235 From: Southern MN Registered: May 2007
If it's worn out bad enough to be sucking oil, the lifters on that cyl are more than likely mushroomed out enough that they won't pop out into the lifter galley. Just pull the rockers and pushrods. We drove a 57 Chevy like that for 2yrs.
The car is for sale, but if he still has it when the snow melts he said he will probably try this. Here is a link to the cars craigslist ad if you want to see: http://eauclaire.craigslist.../cto/3522253402.html
By the way this thread was cool just hearing all the old stories
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11:31 PM
2.5 Member
Posts: 43235 From: Southern MN Registered: May 2007
Caddy had a V8/6/4 back in the 80’s, never got too much info on it other than they disabled pairs of pistons to balance the engine while it was running on 6/4 cylinders. Disabling one piston I would think would make the engine run rough and not be good for it.
... Steve
Yep.
"The L61 had not provided a significant improvement in the company's CAFE numbers, so Cadillac and Eaton Corporation devised a cylinder deactivation system called Modulated Displacement that would shut off two or four cylinders in low-load conditions such as highway cruising, then reactivate them when more power was needed. When deactivated, solenoids mounted to those cylinders' rocker-arm studs would disengage the fulcrums, allowing the rockers to "float" and leave the valves closed despite the continued action of the pushrods. These engines are easily identified by their rocker covers, which each have elevated sections over 2 cylinders with electrical connectors on top. With the valves closed the cylinders acted as air-springs, which both eliminated the feel of "missing" and kept the cylinders warm for instant combustion upon reactivation. Simultaneously, the engine control module would reduce the amount of fuel metered through the TBI unit. " -wiki
This is similar to what he will try to do, cut that one cylinder, but full time. The difference suppose is this is a carb engine so fuel will not be reduced, it will just not be sucked into that one cylinder.
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11:45 PM
Feb 18th, 2013
Rickady88GT Member
Posts: 10649 From: Central CA Registered: Dec 2002
"The L61 had not provided a significant improvement in the company's CAFE numbers, so Cadillac and Eaton Corporation devised a cylinder deactivation system called Modulated Displacement that would shut off two or four cylinders in low-load conditions such as highway cruising, then reactivate them when more power was needed. When deactivated, solenoids mounted to those cylinders' rocker-arm studs would disengage the fulcrums, allowing the rockers to "float" and leave the valves closed despite the continued action of the pushrods. These engines are easily identified by their rocker covers, which each have elevated sections over 2 cylinders with electrical connectors on top. With the valves closed the cylinders acted as air-springs, which both eliminated the feel of "missing" and kept the cylinders warm for instant combustion upon reactivation. Simultaneously, the engine control module would reduce the amount of fuel metered through the TBI unit. " -wiki
This is similar to what he will try to do, cut that one cylinder, but full time. The difference suppose is this is a carb engine so fuel will not be reduced, it will just not be sucked into that one cylinder.
I dont think it is a good idea to do anything like this unless it is a "trail fix" to limp you home. As far as the engines that come stock from the factory with "expendable displacement", they have big issues even to this day after the Auto Makers spent untold millions on the technology. One of the biggest problems is oil consumption and build up. It is impossible to stop oil from being sucked up between the rings and into the combustion chamber. This oil fouls the combustion chamber with heavy deposits of carbon that is an age old foe of the internal combustion engine. BUT a bigger problem is the oil that gets sludged in the rings. This oil sludge will bake in the ring grooves and lands and form a very hard carbon "ring" in each of the ring groves. This carbon deposit will score the cylinder so bad that a rebuild will be needed MUCH MUCH sooner than "normal". Of course this will cause a domino effect of lower compression, high oil consumption, smoke from the tail pipe, rough running engine and on and on.
I can think of more reasons not to deactivate cylinders, but I will stop there.
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11:26 AM
BHall71 Member
Posts: 363 From: Yukon, OK. U.S.A. Registered: Jun 2007
I ran my '85 fiero 2.8L on 5 cylinders for over a year, cam lobe went flat. Pulled the spark plug and ran the spark plug wire over and isolated it so there was no spark hop to ground. Goes without saying it was down on power but still stared without issue and idle was surprisingly not that rough. The car was my beater and is now a parts car for my new '88.
Brian
Pray for Wichita.
[This message has been edited by BHall71 (edited 02-18-2013).]
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09:47 PM
williegoat Member
Posts: 20783 From: Glendale, AZ Registered: Mar 2009
The car is for sale, but if he still has it when the snow melts he said he will probably try this. Here is a link to the cars craigslist ad if you want to see: http://eauclaire.craigslist.../cto/3522253402.html
By the way this thread was cool just hearing all the old stories
Demolition derby car !!!
[This message has been edited by williegoat (edited 02-18-2013).]
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09:56 PM
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williegoat Member
Posts: 20783 From: Glendale, AZ Registered: Mar 2009
I dont think it is a good idea to do anything like this unless it is a "trail fix" to limp you home. As far as the engines that come stock from the factory with "expendable displacement", they have big issues even to this day after the Auto Makers spent untold millions on the technology. One of the biggest problems is oil consumption and build up. It is impossible to stop oil from being sucked up between the rings and into the combustion chamber. This oil fouls the combustion chamber with heavy deposits of carbon that is an age old foe of the internal combustion engine. BUT a bigger problem is the oil that gets sludged in the rings. This oil sludge will bake in the ring grooves and lands and form a very hard carbon "ring" in each of the ring groves. This carbon deposit will score the cylinder so bad that a rebuild will be needed MUCH MUCH sooner than "normal". Of course this will cause a domino effect of lower compression, high oil consumption, smoke from the tail pipe, rough running engine and on and on.
I can think of more reasons not to deactivate cylinders, but I will stop there.
I understand your point. However will the oil baking and sludge problem happen if there is no spark? (Disconnected wire)
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02:12 PM
Feb 20th, 2013
Spoon Member
Posts: 3762 From: Sadsburyville, PA. 19369 / USA Registered: May 2004
In the day I had a 65 GTO and threw rod while racing a Buick Grand sport. There was a slight loss of power and a shimmy to the engine. I made it home about 10 miles away and the next morning I did my diagnostics. Found a the dead cylinder and pulled the plug to check compression which was zero. Couldn't even feel compression with thumb pressed against spark plug hole. I poked a long screw driver into the cylinder and found the piston at top "DEAD" center. I applied pressure and as the piston began its decent I developed stomach cramps. No,, the crank did not move! Long story short, you can run an engine with a disabled cylinder. It depends on how it's disabled. I would of tried it if it weren't for the perforations in the pan. After pulling the pan I discovered the big end of the rod was still on the crank journal keeping the adjacent rod in alignment.
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
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12:09 AM
Rickady88GT Member
Posts: 10649 From: Central CA Registered: Dec 2002
I understand your point. However will the oil baking and sludge problem happen if there is no spark? (Disconnected wire)
It only takes heat for it to bake. So yes it can but at a slower rate and also depends on the "health" of the rest of the engine. Even tho the heat is much lower than a firing cylinder, the problem with no spark is that the oil is not burned off of the top of the piston and that will sludge up. Combustion actually cleans the oil out of the cylinder that has slipped by the rings. BTW the oil is supposed to slip by the rings at a very small amount to lubricate the piston and rings. That in turn will cause the oil to get trapped between the rings and fill the lands. That oil will sludge and harden, losing its ability to effectively lubricate , casing accelerated wear.
(double post, now I know how it happens)
