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tobu posted:Looks like the pressure in my exhaust was too much for the resonator again... The welding was a previous dodge attempt to fill cracks that appeared in it but I think its done this time. So this morning I was adjusting the idle levels on my carb on my van with the engine off in the parking lot at work. I get them adjusted, forgetting that each time I had to adjust a certain screw, I was dumping fuel into the bowls of the carb. I go to start it up, and "WRRRRRRR- BANG!" The loudest backfire I've ever heard. Two E-9's come rushing over, and ask me if I just heard gunshots. I explain that it was a backfire and not an active shooter situation. This afternoon as I'm driving home, I notice the exhaust note sounds a little more aggressive than usual. I get home and decide to take a look underneath, and lo-and-behold I do have an exhaust leak... A Rather Large Exhaust Leak: 
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Aug 21, 2014 05:08
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I blew the exhaust off my Grand Cherokee in that manner. I then cleaned up the hanging half and drove a 318 Magnum ZJ chopped off under the seats for the better part of a year 
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Aug 21, 2014 07:07
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Dannywilson posted:So this morning I was adjusting the idle levels on my carb on my van with the engine off in the parking lot at work. I get them adjusted, forgetting that each time I had to adjust a certain screw, I was dumping fuel into the bowls of the carb. I go to start it up, and "WRRRRRRR- BANG!" The loudest backfire I've ever heard. Two E-9's come rushing over, and ask me if I just heard gunshots. I explain that it was a backfire and not an active shooter situation. This afternoon as I'm driving home, I notice the exhaust note sounds a little more aggressive than usual. I get home and decide to take a look underneath, and lo-and-behold I do have an exhaust leak... A Rather Large Exhaust Leak: Why were you adjusting the idle with the engine off? I was taught to do it while running.
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Aug 21, 2014 14:59
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I blew about a 4x1" rectangle out of a muffler at idle. It happened exactly as a Super Duty pulled up behind me at the light, so I thought I was just hearing his idle. As I roared away, I realized just how wrong that was. An opened up 327 SBC sounds loving awesome.
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Aug 21, 2014 22:43
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Tactical Bonnet posted:Why were you adjusting the idle with the engine off? I was taught to do it while running. If I were adjusting the warm-idle I would, as it is easily accessible on the armature. The cold-idle level screw is down underneath the warm-idle screw on the other end of the armature, so you have to tilt that armature (throttle level) to the stops (IE flooring the accelerator) to get the cold idle screw to into a position where you can even access the cold idle screw. I thought I'd given it enough cooling time, not even thinking about the muffler being a little... warm.
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Aug 22, 2014 01:47
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Dannywilson posted:A Rather Large Exhaust Leak:  What exactly causes this? And what make/model van is that? It looks similar to mine. Edit: I get that there was fuel getting dumped into the carb and such, but all that combustion should happen in the engine, right? Rorac fucked around with this message at 04:30 on Aug 22, 2014 |
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Aug 22, 2014 04:28
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Godholio posted:I blew about a 4x1" rectangle out of a muffler at idle. It happened exactly as a Super Duty pulled up behind me at the light, so I thought I was just hearing his idle. As I roared away, I realized just how wrong that was. An opened up 327 SBC sounds loving awesome. When I replaced my exhaust from the Y-pipe back, I had to see what it sounded like with nothing under the car. With no exhaust even a Volvo B230 sounds loving awesome. 
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Aug 22, 2014 04:28
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Splizwarf posted:When I replaced my exhaust from the Y-pipe back, I had to see what it sounded like with nothing under the car. With no exhaust even a Volvo B230 sounds loving awesome. https://www.youtube.com/watch?v=P4Vh0eidjUg
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Aug 22, 2014 04:37
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Rorac posted:
I wonder too, and present a hypothesis. Dump fuel to the intake manifold, making the air fuel mixture too rich to ignite while cranking and the fuel blows by and into the hot exhaust where it ignites.
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Aug 22, 2014 05:45
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I believe that's called anti-lag. It's your van's way of telling you it wants a turbo.
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Aug 22, 2014 05:48
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Also, hot-spots can develop in earlier "hot tube" style catalytic converters that can ignite the air/fuel mixture. And remember, it's called an afterfire. A backfire is into the intake.
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Aug 22, 2014 05:49
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Rorac posted:
White 1970 Ford E-100. AKA The Rolling Amber Alert. From what I can figure, I shut down, managed to dump a bunch of fuel into the carb, and on start up it was too rich to fully burn in any cylinder, with the resulting goulash dumped into the muffler as a fine mist by E: StormDrain posted:I wonder too, and present a hypothesis. Dump fuel to the intake manifold, making the air fuel mixture too rich to ignite while cranking and the fuel blows by and into the hot exhaust where it ignites. Pretty much what happened really. spookykid fucked around with this message at 05:54 on Aug 22, 2014 |
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Aug 22, 2014 05:50
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That happened to my family's old Mazda minivan when one of the coils in the pack blew. Turns out injecting fuel into a dead cylinder with five others running well means it ignites inside the catalytic converter. We noticed it when my sister, sitting in the back, asked "Dad, why is the floor so hot?"
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Aug 22, 2014 07:05
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Sagebrush posted:That happened to my family's old Mazda minivan when one of the coils in the pack blew. Turns out injecting fuel into a dead cylinder with five others running well means it ignites inside the catalytic converter. We noticed it when my sister, sitting in the back, asked "Dad, why is the floor so hot?" A friend had this happen in his old grand am. It started the trunk on fire after getting the muffler red-hot from the amount of unburnt gas coming out the exhaust. The image of my buddy coming over the hill with smoke billowing behind him while limping it home on two cylinders is one of my all-time funny memories.
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Aug 22, 2014 12:47
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Dannywilson posted:So this morning I was adjusting the idle levels on my carb on my van with the engine off in the parking lot at work. I get them adjusted, forgetting that each time I had to adjust a certain screw, I was dumping fuel into the bowls of the carb. I go to start it up, and "WRRRRRRR- BANG!" The loudest backfire I've ever heard. Two E-9's come rushing over, and ask me if I just heard gunshots. I explain that it was a backfire and not an active shooter situation. This afternoon as I'm driving home, I notice the exhaust note sounds a little more aggressive than usual. I get home and decide to take a look underneath, and lo-and-behold I do have an exhaust leak... A Rather Large Exhaust Leak: Are we posting muffler-sposions? I got a pretty good one.  
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Aug 22, 2014 14:06
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Back in the day of carb'ed bike, my friend had a trick when overtaking assholes. As he was about to pass them, he'd briefly kill the ignition, before restating, just as he passed the driver's window. The loud Worked very well, until one day he did and the bike vomited the exhaust internals onto the motorway.
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Aug 22, 2014 15:07
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And from that day on, it worked even better 
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Aug 22, 2014 16:09
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Shutting off the ignition to my 78 Subaru while pumping the gas makes for an awesome fireball out of the exhaust.
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Aug 22, 2014 16:16
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spog posted:Back in the day of carb'ed bike, my friend had a trick when overtaking assholes. As he was about to pass them, he'd briefly kill the ignition, before restating, just as he passed the driver's window. And this is why when I finally get my bug on the road, it's getting a stinger exhaust.
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Aug 22, 2014 17:18
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Splizwarf posted:When I replaced my exhaust from the Y-pipe back, I had to see what it sounded like with nothing under the car. With no exhaust even a Volvo B230 sounds loving awesome. I did that for shits and grins when I was replacing the gasket coming off of the collector. Yeah, even a shitbox bonestock redblock can sound good like that.
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Aug 22, 2014 17:24
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This needs some love, it's mental.
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Aug 22, 2014 18:10
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Ooo Ooo, can I play? Did this the other day with my truck. Too bad I recorded it with my phone because it sounded mental https://www.youtube.com/watch?v=SPKAZNf6ZcA
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Aug 22, 2014 18:16
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IOwnCalculus posted:I did that for shits and grins when I was replacing the gasket coming off of the collector. Yeah, even a shitbox bonestock redblock can sound good like that. Back on my turbo redblock, the exhaust broke right at the downpipe and it was the most glorious sound for a 17 year old. I drove it around for days like that before fixing it.
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Aug 22, 2014 20:21
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My Protege, after I put on the Corksport exhaust but before adding the AFC, ran rich as gently caress (I'm talking 11.5:1, spiking under ten right when boost came on). I was able to
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Aug 22, 2014 22:20
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My first old rx7 had an extra pipe suspended under the main exhaust system. It seemed to be a cat bypass or something similar. A brief stomp and release of the accelerator resulted in a heroic bang out the back of that pipe. Great fun at stoplights! That whole car was the definition of Automotive Insanity. I bought it for $250 off a guy that auto-xed it... the thing was gutted and lightened, and had all sort of engine fuckery done to it. Lightened flywheel, bridged ports (whatever the hell that means), the previously mentioned cat bypass, etc. I eventually used it as my snow/salt car but only after I put a set of hakkapeliittas on. 2300 lbs, 150HP and an LSD. Hilarity. I sold it about 5 years later when I bought my first Audi. I regret both decisions. buttcrackmenace fucked around with this message at 23:25 on Aug 22, 2014 |
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Aug 22, 2014 23:08
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I can set off car alarms by goosing the throttle in the MJ. It's great fun. (A cat with crohns disease, a glasspack, and a turndown instead of 6 feet of tailpipe makes for a slightly more aggressive exhaust tone, who knew?)
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Aug 22, 2014 23:11
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That's also how they did the classic hot rod exhaust flamethrowers -- install a switch that cuts out a sparkplug or six up front and activates a sparkplug in the tailpipe. Rev it, bump the switch. Obviously it works best with mufflers that are only technically legal. Well, it works best with no mufflers at all, but there's not much difference between a proper glasspack and a solid pipe, aside from passing inspection in rural Texas.
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Aug 22, 2014 23:26
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Bad Angus! Bad!
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WARNING: Jeep/Dodge 4.7L V8 lovers look the other way! So I've gotten a few questions about why 4.7L (and related 3.7L V6, and apparently the 5.7L Hemi V8) Mopar modular V8s suck. And people doubting that it's actually a problem, maybe I'm blowing it out of proportion... Issue: insufficient pressfit on the valve seats. Alloy head, sintered powder metal valve seats (much lower CTE than aluminum.) Fine until you overheat it a little or just get unlucky, then they fall out and shatter into a million engine-destroying fragments. Sometimes they even get blown through the open valve hole into the intake manifold... and sucked into other cylinders. Result:           Lifted from: http://dodgeforum.com/forum/jeeps/330406-jeep-carnage.html http://forums.corral.net/forums/lounge/1255217-so-grand-cherokee-wasnt-blown-up-head-gasket-fine-pic.html http://southeastcylinderhead.com/caution-repairing-engines-with-broken-valve-seats/ http://forums.pelicanparts.com/off-topic-discussions/679236-need-some-opinions-about-jeep-engine-failure.html http://www.jeepforum.com/forum/f310/jeep-wj-4-7-engine-problem-1128211/index2.html http://www.jeepforum.com/forum/f310/engine-damage-valve-seat-2013185/ http://www.jeepforum.com/forum/f310/4-7-not-ho-wj-2-piston-damage-opinion-needed-1544120/ Here's a super special one. Rather than the valve seat dropping, the valve snapped off, smashed the gently caress out of the valves, head, piston, broke the conrod. The following are all from a single engine.                    All from: http://www.jeepforum.com/forum/f310/think-my-4-7-engine-grenaded-1388089/ e: goddamnit SA, why didn't you thumbnail these properly, stand by (fixed) kastein fucked around with this message at 00:13 on Aug 23, 2014 |
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Aug 23, 2014 00:05
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buttcrackmenace posted:My first old rx7 had an extra pipe suspended under the main exhaust system. It seemed to be a cat bypass or something similar. A brief stomp and release of the accelerator resulted in a heroic bang out the back of that pipe. Old RX-7s had trouble meeting emissions standards even before catalytic converters were a thing, mostly because of unburned fuel and incomplete combustion products (long, narrow combustion "chamber" = cool combustion = lots of soot) so Mazda's first solution was something called a "thermal reactor". Basically an air pump into a chamber high up in the exhaust system that allowed the combustion to complete and turn the soot and CO into less objectionable CO2. (ie: fuel keeps burning inside the exhaust system). Could it have been that? I ask just because all the RX-7s I've seen have And "bridged ports" is one of the more drastic mods you can do to a wankel. There aren't any cams or valves to adjust to get increased gas flow, so if you want more intake or exhaust potential you have to literally enlarge the ports like you would on a 2-stroke. As you grind away material, eventually they get so large that you can't get any bigger without having the apex seal fall out into the port as it traces its path along the rotor housing. The solution is to stop there, leave a line of material ("bridge") that the seal rides on, and keep hollowing out on the other side. Standard port  Expanded port  Bridged port  Bridgeports have terrible idle characteristics, just like a huge lopey cam designed for the dragstrip does, but you probably already knew that. Sagebrush fucked around with this message at 00:20 on Aug 23, 2014 |
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Aug 23, 2014 00:16
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Splizwarf posted:When I replaced my exhaust from the Y-pipe back, I had to see what it sounded like with nothing under the car. With no exhaust even a Volvo B230 sounds loving awesome. I've been putting off re-attaching the catback on my chevy 4.3 for that reason. Come to think of it, I even have a redblock available to me... Should I put a redblock in an S10 Blazer?
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Aug 23, 2014 00:31
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god damnit ken i was trying to ignore the reality of my 4.7
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Aug 23, 2014 01:38
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I thought the Dodge 4.7 sucked because it made lovely power for a V8 and drank gas like an alcoholic at an open bar wedding reception.
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Aug 23, 2014 02:11
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Dr.Smasher posted:I thought the Dodge 4.7 sucked because it made lovely power for a V8 and drank gas like an alcoholic at an open bar wedding reception. Why would they drink gas if there's an open bar?
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Aug 23, 2014 02:55
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Sagebrush posted:Why would they drink gas if there's an open bar? Watered down drinks.
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Aug 23, 2014 04:08
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DJ Commie posted:Shutting off the ignition to my 78 Subaru while pumping the gas makes for an awesome fireball out of the exhaust. This also made one of the most AI photos. Post the photo of the fireballs.
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Aug 23, 2014 04:19
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This is a terrible place to ask, but what could cause a 2nd gen RX-7 to not want to rev above a certain rpm? Specifically, approximately 3krpm.
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Aug 23, 2014 05:25
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Tactical Bonnet posted:This is a terrible place to ask, but what could cause a 2nd gen RX-7 to not want to rev above a certain rpm? Specifically, approximately 3krpm. Not a rotary expert at all but I would hazard to say you're in limp home mode.
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Aug 23, 2014 05:31
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I'm not in anything, but a friend of mine is, and since I "know about cars, right?" I was the person he asked.
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Aug 23, 2014 05:36
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Tactical Bonnet posted:I'm not in anything, but a friend of mine is, and since I "know about cars, right?" I was the person he asked. S4 or S5 FC? Edit: The S5 ('89-'92) was the first RX-7 with an electronically controlled OMP. Its directly controlled by the ECU, and not electrically isolated well, so overtime the OMP servos and stuff will degrade, short, and cause the ECU to burn out. The ECU will detect a malfunction, and put the car in limp mode. If your friend pulls the codes, they'll usually get either 20, 22, or 27 (different specific OMP failures). Keep driving it, and if they haven't already, they are pretty much gonna fry the ECU. They really should figure out what the actual failure is, but typically you are looking at replcing the OMP and the ECU. Most folks convert to a manual S4 OMP, and either chip the ECU to disable the electronic OMP controls (and thus the CEL and limp mode) or run an aftermarket EMS like a megasquirt. I was lucky, the FC that gave me issues with the OMP was the connector next to the alternator. The contacts would corrode over time and cause additional resistance which would make the ECU think there was a failure. Clean up the contacts, and I would make limp mode disappear for a while. Brigdh fucked around with this message at 05:54 on Aug 23, 2014 |
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Aug 23, 2014 05:47
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Sagebrush posted:Why would they drink gas if there's an open bar? Because ethanol destroys fuel systems.
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Aug 23, 2014 06:26
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