Making a V8 a V7/V6
11-21-2011, 11:05 PM
#1
Senior Member
Thread Starter
Making a V8 a V7/V6
Okay maybe this isn't possible/reasonable, but I lost my #5 cylinder rings at least (302, Automatic), so trying to figure out how to buy a month and a half worth of time....I'll have some $ freed up to get something else and work on this, or pay to have it worked on. *Daily driver, and no spare so can't be down long.
Truck runs ok at speeds other than idle and takeoff. At idle it runs rough, at idle in gear quite rough, so at stops I shift her in neutral. At takeoff it just doesn't really want to go, and once it does a fair puff of smoke out the tailpipe.
My thought is what if/could I block off fuel flow to the #5 cylinder, or just pull the plug wire - would that help with the slight oil burn and possibly run smoother?
What if I also block off fuel and spark to the #1 cylinder? Now it should run more even, temporarily anyway.
Worse case I can think of is causing more damage cylinder and/or valves from the oil leaking past the sidewalls and not com-busting as normal and then finally trying to compress a cylinder full of oil.
Not sure how the displacement on demand engines work, but it's gotta be something similiar, short of possibly forcing the valves to stay 'lifted' in off mode? Just a refrigeration guy, so trying to relate compression and combustion.... With that said maybe there's a way to leave the valves on the unused cylinders lifted to minimize trying to compress oil?
Thoughts? Maybe I've been breathing too much burned oil exhaust lately?
Truck runs ok at speeds other than idle and takeoff. At idle it runs rough, at idle in gear quite rough, so at stops I shift her in neutral. At takeoff it just doesn't really want to go, and once it does a fair puff of smoke out the tailpipe.
My thought is what if/could I block off fuel flow to the #5 cylinder, or just pull the plug wire - would that help with the slight oil burn and possibly run smoother?
What if I also block off fuel and spark to the #1 cylinder? Now it should run more even, temporarily anyway.
Worse case I can think of is causing more damage cylinder and/or valves from the oil leaking past the sidewalls and not com-busting as normal and then finally trying to compress a cylinder full of oil.
Not sure how the displacement on demand engines work, but it's gotta be something similiar, short of possibly forcing the valves to stay 'lifted' in off mode? Just a refrigeration guy, so trying to relate compression and combustion.... With that said maybe there's a way to leave the valves on the unused cylinders lifted to minimize trying to compress oil?
Thoughts? Maybe I've been breathing too much burned oil exhaust lately?
Last edited by gwpfan; 11-21-2011 at 11:07 PM. Reason: *
11-22-2011, 02:33 AM
#2
Jordan
No idea on how well it'd run...probably really off balance haha
If you really wanted to stop the valves in that cylinder you would remove the rocker arms and pushrods. But then that'd be an energy block constantly compressing and decompressing, with no firing or anything. Interesting...
If you really wanted to stop the valves in that cylinder you would remove the rocker arms and pushrods. But then that'd be an energy block constantly compressing and decompressing, with no firing or anything. Interesting...
11-22-2011, 03:09 AM
#3
If you are going to do any of that... I would pull the plug wire...Not the fuel.....
How do you know its the rings?
How do you know its the rings?
11-22-2011, 03:36 AM
#5
Senior Member
I would say don't drive it till it's fixed if you plan on keeping it... Your gonna end up making way more work out of it...
If you did shut down cylinders, I would say you would have a ton of parasitic loss of power from the cylinders that are down and not firing... Making it harder on the rest of em to constantly have to spin the crank around for the other two...
It's like you got 8 people in the rainforest and two of em got injured, now ya gotta carry em out... People are gonna get tired quick and be tripping and falling before they get out alive... (running rough) eventually at least one of those two people will die but the rest are forced to continue to carry em anyway...
If you pull push rods and rocker arms the valves will remain closed, not good... and the other chambers would be fighting the awkward suction and compression, most likely won't run...
I would say don't run it but I know you need it... If anything run it on the injured cylinder the way it is and keep it close to home but I wouldn't recommend it
If you did shut down cylinders, I would say you would have a ton of parasitic loss of power from the cylinders that are down and not firing... Making it harder on the rest of em to constantly have to spin the crank around for the other two...
It's like you got 8 people in the rainforest and two of em got injured, now ya gotta carry em out... People are gonna get tired quick and be tripping and falling before they get out alive... (running rough) eventually at least one of those two people will die but the rest are forced to continue to carry em anyway...
If you pull push rods and rocker arms the valves will remain closed, not good... and the other chambers would be fighting the awkward suction and compression, most likely won't run...
I would say don't run it but I know you need it... If anything run it on the injured cylinder the way it is and keep it close to home but I wouldn't recommend it
11-22-2011, 03:38 AM
#6
Senior Member
Originally Posted by Just call me Sean
If he pulled the spark and didn't stop the fuel it's going to go into the oil. Best to drive it as is.
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11-22-2011, 11:39 AM
#8
Senior Member
Thread Starter
Figured I'd have loss but didn't figure that much, nice analogy can't just leave the comrades! It does have me wondering how the displacement on demand works, granted they go back to 4 cylinders, at least what I know of...*Read up on it a bit more - they're leaving comrades until needed.. ;o)
I assume its the rings as when it was cranked with no plugs that cylinder blew out some of the crud that was around the spark plug hole, but I haven't done a compression test. Just guessed that a broken rod/piston wouldn't blow out the crud on that cylinder plug hole.
FWIW - I had fine metal shavings in the oil when I did the oil change Sunday afternoon
I assume its the rings as when it was cranked with no plugs that cylinder blew out some of the crud that was around the spark plug hole, but I haven't done a compression test. Just guessed that a broken rod/piston wouldn't blow out the crud on that cylinder plug hole.
FWIW - I had fine metal shavings in the oil when I did the oil change Sunday afternoon
Last edited by gwpfan; 11-22-2011 at 11:54 AM.
