Oyaji

I expect that is for safety, and that continuous bead welding is specified for the reason of keeping out potential for ingress of exhaust gas from a leaking exhaust system. Diligent seam sealing is the cure in locales that allow riveting.

Indeed. Interestingly, a glued lap joint can be stronger than the base material:

Sounds like you don't have a spark issue, but maybe an issue with injectors with too high of a flow rate. Clean the plugs with a bead blaster, put them back in with the old injectors, and try it again (if you can't get the plugs clean, put in a new set instead). If the clean plugs come out black and sooty with the old injectors, you have a sensor issue or fuel pressure regulator issue. If they show a decent mixture, the new injectors are flowing too much... too much even for the control unit's ability to lean them out by shortening the injector pulse.

Just curious - why a trailer instead of a towbar?

Another nice thing about blind rivets is that if you ever have to redo the job sometime in the future, it's easy to just drill and punch them out... The end result isn't as pretty as welding, but how much time do you spend looking under the carpet and the underside of the truck anyway? ;)

Geez - it's warmer in north Georgia than it is down here at the moment. Yesterday I was sweating in shorts and a t-shirt, but today I had to put on long pants and a sweater. High today is a blustery 50 degrees F. Tomorrow is supposed to be better: high 70, low 60, but 40% rain chance. :( At least I didn't have to put on socks today to keep my feet warm. Hope you guys farther north get a break in the weather soon so you can get stuff done.

Per the thread title, I have a couple questions about the 4.0 I-6 engine block. I know that ultimately the solution will be to mic the cylinders to see what the condition of the block actually is, but would appreciate some general advice about what to expect before tearing engines down. First, what is commonplace for wear? Does the 4.0 typically need to have the cylinders bored for an overhaul, or is it typical to be able to get away with simply honing and going back with standard pistons? (For that matter, how well do the pistons usually hold up - should one plan on replacing them too, or can a set of rings suffice?) Secondly, can a simple re-ringing be accomplished with the engine in place by just pulling the head, dropping the oil pan, removing the rod caps, and pushing out the rods and pistons? Is there a difference in available clearance depending on 2wd versus 4wd? And do the main bearings generally hold up well enough to reuse them and only just replacing the rod bearings (provided that the rod bearings are still in the babbit)? I do realize that individual cases will vary, that ultimately there are no reliable shortcuts, and that blind faith is no substitute for diligence and proper method, but I am just looking for generality here. If it makes any difference whether HO or Renix engines, please note the differences in your experience. Any other tips would be greatly appreciated as well. Thanks in advance.

Rather than welding, what do you guys think of using a double staggered row of stainless steel blind rivets?

Very nice practical contribution - thank you for sharing it.

Roger that. It's worth keeping in mind that the primary restriction contributing to pumping losses in any gasoline engine is the throttle plate, which for almost all driving is mostly closed. Best gains to be had would come from reducing restriction in the exhaust, but that would be most pronounced for high load demand when flow is increased, same for reducing restriction in the intake. False. The best gains are when you reduce the restrictions in both (but too much). Firstly, air can only come in as fast as it can go out and it can only go out as fast as it's coming in. Secondly, (I'm just saying this in general not to you- I realize you said reduce and not eliminate) back pressure actually helps a motor run, you need it. If you have ever ran a 4.0 on just straight headers you'll one know they're loud as heck lol but other than that the butt dyno can actually feel a loss of power. Roger - on headers you need to run at least a section of exhaust downstream from the collector to get benefit. That's not so much to add restriction but to smooth out flow and to provide a section of pipe to take advantage of the momentum of the gas in the flow (plus to use the momentum of the exhaust gas pulses from each cylinder to help scavenge/draw flow from the others). It's the same principle as the hydraulic ram effect. Simple example: notice the pulse you get from suddenly releasing the handle of a garden hose spray nozzle - you feel the surge as the momentum of the moving water that wants to keep moving but can't because you closed the valve at the end of the hose. The moving column of water inside the garden hose has mass that has inertial momentum and wants to keep moving. Any mass in motion has that same inertia, gases included. That's why you get benefit from having a section of pipe downstream from a header. It gets more complicated than this simple explanation, but suffice it to say that you can tune the power increase for engine speed (RPM) by changing the pipe length.

Roger that. It's worth keeping in mind that the primary restriction contributing to pumping losses in any gasoline engine is the throttle plate, which for almost all driving is mostly closed. Best gains to be had would come from reducing restriction in the exhaust, but that would be most pronounced for high load demand when flow is increased, same for reducing restriction in the intake.

Ever since they came out some years ago, I have been telling folks that cold air intakes are a "snake-oil" hokum product that does not produce the power gain claimed in excess of stock, and in fact is potentially harmful since engines so equipped are vastly more susceptible to ingesting water that can cause hydro-lock (which stock systems are designed to circumvent). Few would listen, as common sense would lead one to believe that such should work as advertised. But folks don't have to take just my word for it, because nowadays there are heaps of exposés - here is one:

Stock power should be at least adequate to handle any paved road in the country. I see you live in California. An emissions check is a pre-sale requirement there, right? Passing results from a proper check would indicate that the engine is running not too far off its stock performance... provided a proper check was done. In case it wasn't done, make sure it is in a good state of tune. Reading the spark plugs can tell you much. A partially plugged catalytic converter can drastically cut power output. Have a "test pipe" fabricated (or fab one yourself) and bolt it in to replace your cat. It is (or was and still should be) legal even in your state, and you might like the results so much that you decide to run quite a long test. ;) (Being prepared to show the last week's data - for instance, fuel economy data - might be a good idea in case you get caught. Having more than a week's data on hand might be hard to explain though! :D) Just to cover all the bases here, I should ask - you are down-shifting that 5-speed to keep the revs up for the hills, right?

I dunno why, but the DC 12 volt compressors are EXPENSIVE. For that reason I am thinking of just using a small AC 110 volt that can be had cheaply at Harbor Freight. Though my general rule is "don't buy anything with moving parts if it is made in China", their quality seems to be improving, and duty on my truck will be light, so it may be OK. (I do have a use for an on-board inverter already, so that part of it will not be a cost directly applied to having on-board air.)

Ayup - almost 400 times more once you expand the liquid into a gas. Density of liquid CO2 is 770 kg/m3 , but gaseous CO2 is only 1.977 kg/m3 (at STP [standard temperature and pressure]).

Oh? Then you should have no trouble quoting sources to back up your knowledge, right? Anyone can present himself as an expert on the Internet, but the readership finds it hard to distinguish between a true expert and a blowhard if the only supporting evidence for something quoted as gospel is "because I said so". Doubtless you know that. Personal experience does count for a lot, but everyone should recognize that such is only that of one man and is no more valid than that of another. I look forward to profiting from your experiences and those of others here on the forum. I sincerely do wish we could work together, though that chance seems remote at this time.

No - he TOLD me to, in an ultimatum. Most people don't take well to be ordered around, and I am no exception... but I do take your point. Besides, I recognize that he has a lot of useful information to offer - I said as much in a number of posts, most recently in #5 above. (My arm is getting tired from offering that olive branch... :D) But that does not make him nor anyone else infallible. When I make a mistake, I thank the person who corrected me for not leaving me in error - that is in fact a kindness. I suggest that accepting criticism in that way is a good approach and just plain good manners, but anyone is free to choose how to do that for himself. I'd much prefer to work together - we are all on the same team here, right? Besides, the quest for knowledge and some brain exercise is fun. Part of that is presenting ideas and arguing their merits. If we don't consider every opinion and instead invoke censorship (whether self-imposed or by a higher authority) then we limit discourse, which limits our opportunities. So long as we keep it civil, the quest for knowledge should be both fun and profitable, for all participants and all who read thereafter. It would make us poorer to limit ourselves, so why not work together and profit from the experience? :) Will Rogers said, "I never met a man I didn't like." Interacting through text falls short of talking - you just can't pick up the nuances of what is being said when it's all just words on a page. Doubtless it's a good thing here to make allowances for that. We would probably all be friends if we drove our MJs someplace and got together for beer and barbecue and focused on what we have in common, so I am all for being friends here too. I just expect it to be a bit harder, that's all.

I don't - but it does not bother me either way whether or not I do. Really, I am concerned most with information and its transmission, not who it comes from or whether they like me or not. I like to learn, and I offer what I can in return. I like to know more than just how to fix something, because the better I understand the subject matter behind a problem, the better I can be about how to figure out how to fix it or how to make a product better. I'd like to think we all have that in common, but I cannot be overly concerned about what other people think, because that is something beyond my control. I will say that I enjoy the company of people who enjoy the journey more than arriving at the destination, but I have no problems with whatever path a person chooses - as long as they don't step on my toes as they go their way and are not malicious about it.

That, plus even if you don't block them, you are not required to read every post. And no one forces you to respond to anything that you read, either. Terms of service do limit what you can say when you do choose to respond though, though. ;)

Not just plastic and rubber - you can add paint to the list of non-conductors... in every-day life that means pretty much everything not made of metal.

Only things made of metal will reflect radio waves. If you have a plastic bedliner, it has no effect on the metal beneath reflecting waves and acting as a ground plane. You should certainly have grounded your antenna though - you didn't by chance mount it to plastic and not to metal, did you? Regardless - you still have a problem, so recheck your antenna connections.

Glad you got it whipped. :) Guess I don't need to remind you that you need to get that manifold replaced before you poison yourself with carbon monoxide, right? ;)

:yeah that: Good stuff, better than my attempt at typing a description. If a picture is worth a thousand words, a video must be worth a million!

I was afraid that might be the case... sure you cannot just unscrew the backing plate off the assembly and take it apart? If not, you'll have to pick it first. That will be a test of patience, but it is doable. Make yourself a tension tool that leaves a gap between an upper and lower "prongs" spaced so that they will slip into the keyhole at the outer extremes. The prongs should be maybe an eigth of an inch long before bending 90 degrees and terminating in a 6-inch handle. Best made of spring steel, anything you can use to hold gentle pressure to turn the lock cylinder in the direction of unlocking will do. Next, make a rake pick out of a stiff piece of wire. It can have a single 45 degree bend in the tip, or a 45 followed by a 90 and another 45 degree bend. An improvised grip of some sort will help; overall length should be about 6 inches. To use the tools to open a lock, place the lock body in a padded vise and snug it just enough that it won;t move (being careful not to crush it - they are often made of pot metal), apply tension in the direction of unlocking with one tool while using the rake to bounce the pin/disc tumblers up from their spring-loaded down positions. Since the tumblers will have a little variation from manufacturing, some will clear the lock body ahead of others. Holding tension with one hand while you work the rake in and out will often allow the tumblers to pop into place one by one; once all are lined up the lock will open. Presto! Now you can take it apart and re-key it. If you don't get it open in 15 minutes, give up and go do something else. Come back to it another time, vary your technique, and you may succeed. They say there is a touch to it, and I know I can feel tumblers engaging one or two at a time - try to vary the order that you manipulate the tumblers. Once you feel those that engage in a certain order, repeat that sequence as you try to get the remaining ones to release. I know if you are patient you can do it. If you can't get it in a reasonable amount of time, just buy another lock and avoid the frustration. :)

Connect 3 of them in series and it would be a lot closer to proper resistance, it appears.