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    #16
    Originally posted by KH990j View Post
    I got the engine to stall less by getting the carburetor tuned somewhat. The engine was running lean due to the float not being set correct. I hooked a scan tool with a dwell setting on it to the metering system but I was going some whacky readings. I realized later that I didn't have the MAP sensor plugged in and the ECM was running open loop. I tuned to carb as best I could to keep the engine running but it's rough right now. I'll need to acquire my own dwell meter and spend more time on it. The magic number is 35°of dwell. The ECM does function as I can tell it was trying to make it's own corrections as best as it could. There is still plenty of hesitation while the engine is cold but it's not as bad.
    Hey just a question. On these carbs, the tip-in throttle response is still controlled by an accelerator pump. If the plunger is deteriorated and not pumping in the correct mist of fuel, it can hurt the tip-in response.

    Another possibly issue is the oxygen sensor. If this is contaminated with certain chemicals it will make the computer system run the engine too lean when in closed loop.

    I respect your reason to keep it original. There are very few of these left out there!

    Also, I have to ask - Have you ensured that the original plastic timing chain sprocket has been removed and replaced with a steel one? That is what usually kills these engines. Not only do they have a significant interference between the valves and pistons; the sprocket will break up into chips that clog the oiling system. This happens well before the timing jumps so the damage is silent; until it's too late.

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      #17
      Originally posted by turbokinetic View Post
      On these carbs, the tip-in throttle response is still controlled by an accelerator pump. If the plunger is deteriorated and not pumping in the correct mist of fuel, it can hurt the tip-in response..
      Bingo!

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        #18
        Originally posted by turbokinetic View Post
        Hey just a question. On these carbs, the tip-in throttle response is still controlled by an accelerator pump. If the plunger is deteriorated and not pumping in the correct mist of fuel, it can hurt the tip-in response.

        Another possibly issue is the oxygen sensor. If this is contaminated with certain chemicals it will make the computer system run the engine too lean when in closed loop.

        I respect your reason to keep it original. There are very few of these left out there!

        Also, I have to ask - Have you ensured that the original plastic timing chain sprocket has been removed and replaced with a steel one? That is what usually kills these engines. Not only do they have a significant interference between the valves and pistons; the sprocket will break up into chips that clog the oiling system. This happens well before the timing jumps so the damage is silent; until it's too late.
        Y'know it's been so long, I completely forgot about the accelerator pump. With the alcohol laced gas a lot of cars are forced to ingest-- that would be a real problem. I just drove 30 miles to get some alcohol free gas today for my small engines. Very expensive in Texas ($4.75/gal.)....or I can drive to Wisconsin or Alabama or Oklahoma. Ironic since all that gas is probably refined here in my locality.

        Ken T.

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          #19
          Originally posted by Century7667 View Post
          ..alcohol free gas..
          Sidenote- Around here, some 30 or so cents higher than 10% blended. I don't know the details, but there is a "lottery" like mechanism where resellers can buy pure unleaded. Specifically, it has to do with this: "Renewable identification numbers (RINs) are credits are the “currency” of the RFS program. Renewable fuel producers generate RINs."

          I would like to think newer carb kits are designed for 10% blend.

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            #20
            Yup, that damned Ethanol is killing my equipment here too. Had to rebuild the carburetor on my lawn mower due to fuel issues. The lawn mower is only 1 year old. I have to use Premium fuel in it to keep it from screwing up. Or use additives in the lower grade fuels to keep the carb clean. It's actually cheaper for me to just buy a gallon or two of Premium. What this is doing to the injectors on the '93 Century I don't know as of yet. I'm hoping the newer injectors I put in her a couple years back are designed to handle the alcohol rich fuels. I also replaced the fuel pump not too long ago. I wish we could just go back to using real gasoline again. Not to mention that this newer fuel doesn't last long either. You can't store it for very long before it goes flat. Poor old cars.

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              #21
              Originally posted by CorvairGeek View Post
              I'll have to take a picture of an Ultra Low Emission Vehicle 3100 V6 with air injection for everyone's amusement.
              That was the first thing that was deleted on my car. They put the AIR pump where the power steering should have gone.

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                #22
                Originally posted by Century7667 View Post
                This was why I had suggested to KH990j to consider a retrofit to a DualJet carb. I think that would be close enough to original, not like ripping out the 3.0 and replacing with with the 2.8 or the 3.8 or even a 3.3. The DualJet would be a period correct carb for the car.

                Ken T.
                I suppose you're referring to the standard DualJet and not the E2ME DualJet that mine has?

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                  #23
                  Originally posted by turbokinetic View Post
                  Hey just a question. On these carbs, the tip-in throttle response is still controlled by an accelerator pump. If the plunger is deteriorated and not pumping in the correct mist of fuel, it can hurt the tip-in response.

                  Another possibly issue is the oxygen sensor. If this is contaminated with certain chemicals it will make the computer system run the engine too lean when in closed loop.

                  I respect your reason to keep it original. There are very few of these left out there!

                  Also, I have to ask - Have you ensured that the original plastic timing chain sprocket has been removed and replaced with a steel one? That is what usually kills these engines. Not only do they have a significant interference between the valves and pistons; the sprocket will break up into chips that clog the oiling system. This happens well before the timing jumps so the damage is silent; until it's too late.
                  This one does have the TPS under the plunger, but I only bought this carburetor back in 2012 and it probably has about 10k miles on it so I don't think the TPS is at fault.

                  The oxygen sensor was replaced in early 2009 and probably has 20k-30k miles on it. I could be faulty again.

                  I guess the reason to keep it original like this is not so much for performance, obviously although I wonder if it really does help with fuel economy, but it's kind of a historical piece from the days of primitive electronic controls. My challenge is to see if I can keep it running somewhat correct.

                  I have yet to replace the timing chain sprocket, and I'll try to get it done when I move in to a new place. The car is not a daily driver; in fact it's more of a school project. It sure fascinates students who have never seen such technology and it gets the attention of older instructors who haven't seen these cars in years.

                  Comment


                    #24
                    Originally posted by Century7667 View Post
                    Y'know it's been so long, I completely forgot about the accelerator pump. With the alcohol laced gas a lot of cars are forced to ingest-- that would be a real problem. I just drove 30 miles to get some alcohol free gas today for my small engines. Very expensive in Texas ($4.75/gal.)....or I can drive to Wisconsin or Alabama or Oklahoma. Ironic since all that gas is probably refined here in my locality.

                    Ken T.
                    I try to get tier 1 gas such as Shell or BP. The Shell station in Lima, Ohio has very little alcohol. I run Sta-bil in it as well to help with the alcohol issue.

                    Comment


                      #25
                      Originally posted by KH990j View Post
                      I suppose you're referring to the standard DualJet and not the E2ME DualJet that mine has?
                      Correct. If it will bolt on. We had one on '80 Malibu; 15 years service / 150,000 miles, never had to be rebuilt. Excellent drivability. They had one for the 200 CID Chevy V6 on the '78-'79 models, so that should be very close as far as size to your 3.0.

                      Ken T.

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                        #26
                        It's fun to see how people react to an old car like this, especially the older instructors who used to work on them!

                        I would advise you ASAP to get on that timing set as this can really wreck the engine. If the sprocket is wearing down or failing, it can cause the ignition timing to become retarded, which will affect the operation of the engine. That could contribute to the poor running.

                        As for the TPS, I don't think that really has much to do with the problem you're having. It would more be the actual mechanical pump plunger inside the carb, not delivering a spray of fuel into the carb bores when the linkage is opening.

                        Originally posted by KH990j View Post
                        This one does have the TPS under the plunger, but I only bought this carburetor back in 2012 and it probably has about 10k miles on it so I don't think the TPS is at fault.

                        The oxygen sensor was replaced in early 2009 and probably has 20k-30k miles on it. I could be faulty again.

                        I guess the reason to keep it original like this is not so much for performance, obviously although I wonder if it really does help with fuel economy, but it's kind of a historical piece from the days of primitive electronic controls. My challenge is to see if I can keep it running somewhat correct.

                        I have yet to replace the timing chain sprocket, and I'll try to get it done when I move in to a new place. The car is not a daily driver; in fact it's more of a school project. It sure fascinates students who have never seen such technology and it gets the attention of older instructors who haven't seen these cars in years.

                        Look me up on Facebook

                        Comment


                          #27
                          Originally posted by turbokinetic View Post
                          I would advise you ASAP to get on that timing set as this can really wreck the engine. If the sprocket is wearing down or failing, it can cause the ignition timing to become retarded, which will affect the operation of the engine. That could contribute to the poor running.

                          As for the TPS, I don't think that really has much to do with the problem you're having. It would more be the actual mechanical pump plunger inside the carb, not delivering a spray of fuel into the carb bores when the linkage is opening.
                          Did they ever do a recall on the timing sprocket or was that something the owner would have had to do themselves? If I still have to do it myself, what part would I need to get to replace it. I'm guessing they used plastic to help reduce rotational force considering the engine produces such low power, and it was cheaper than aluminum. Do all Buick 3.0s have the plastic timing gear?

                          I did a leakdown test in class a couple weeks ago (which turned out well for its mileage) and I checked to see if the timing chain had slack by looking at the distributor, and moved exactly when the crank moved so that looks good.

                          The plunger works fine, again this is a rebuilt carburetor I bought several years ago and things check out on it except it could use a new gasket between the main carb body and air horn since it does have tears (could be from when I checked the float), but a propane test didn't reveal any leaks through it. I've got a newer gasket on an unused carb that I'll probably just put on the new one.

                          I think there could be a pretty good vacuum leak or a leak from somewhere but I'm still not sure. Could a leaking vacuum hose on the transmission affect engine performance?

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                            #28
                            Originally posted by KH990j View Post
                            Did they ever do a recall on the timing sprocket or was that something the owner would have had to do themselves? If I still have to do it myself, what part would I need to get to replace it. I'm guessing they used plastic to help reduce rotational force considering the engine produces such low power, and it was cheaper than aluminum. Do all Buick 3.0s have the plastic timing gear?
                            I don't think there was a recall, because it takes so long for the gears to disintegrate, but the problem is real. We've seen sad photos over the years of engines with plugged oil pick up strainers. It's just one of those things. The L82 3100 V6 has the LIM issue, which is equally devastating if left untended, and these 80's Buick V6es have their plastic gears. While it's not the funnest job in the world, it's worth it for peace of mind.

                            Can't tell you if all 3.0 Buicks had plastic gears or not, but I think it's worth it to verify what you've got in there. It could be a ticking time bomb.

                            David has quite the resume with with Buick V6 engines (and others). I've known him for nearly 10 years, and he's never given me any bad advice.

                            Ken T.

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                              #29
                              Nearly all domestic, light duty V8s used the nylon coated, pot metal, camshaft timing gear under the guise of running quietly. They would generally run 100K miles and keep going, or might disintegrate at any moment. Putting them in what was a comparatively rough, 90 degree V6 was asinine, and an interference engine at that.
                              If it was me, I would probably get something like this and change the timing set ASAP;
                              https://www.rockauto.com/en/moreinfo...sn=455&jsn=455
                              The prices are shockingly low too!
                              However, if David recommends a certain timing set for this era Buick V6, you would be wise to heed his advice.
                              Jerry

                              Comment


                                #30
                                Originally posted by Century7667 View Post
                                I don't think there was a recall, because it takes so long for the gears to disintegrate, but the problem is real. We've seen sad photos over the years of engines with plugged oil pick up strainers. It's just one of those things. The L82 3100 V6 has the LIM issue, which is equally devastating if left untended, and these 80's Buick V6es have their plastic gears. While it's not the funnest job in the world, it's worth it for peace of mind.

                                Can't tell you if all 3.0 Buicks had plastic gears or not, but I think it's worth it to verify what you've got in there. It could be a ticking time bomb.

                                David has quite the resume with with Buick V6 engines (and others). I've known him for nearly 10 years, and he's never given me any bad advice.

                                Ken T.
                                I think that one of the ways GM justified this shitty design was by claiming it was already "industry standard." In other words, other manufacturers had timing system maintenance requirements at less than 100,000 miles. Others were coming on the market with rubber timing belts that had 50 - 60,000 mile replacement intervals; so GM figured that specifying the cam sprocket to be a maintenance item it was OK. They operated on the principle that "We put it in the maintenance manual - therefore if it fails after this amount of miles or years, it's the owners fault due to neglected maintenance." The problem here is, the timing belt engines were designed from the ground-up with some thought for access to the belt area; whereas the GM V6 / V8 engines were originally designed for a timing chain setup that would not require regular maintenance. Therefore it is unexpected to need this job; and the job its self it more invasive to the engine than a belt replacement on the competition's engines.

                                Originally posted by CorvairGeek View Post
                                Nearly all domestic, light duty V8s used the nylon coated, pot metal, camshaft timing gear under the guise of running quietly. They would generally run 100K miles and keep going, or might disintegrate at any moment. Putting them in what was a comparatively rough, 90 degree V6 was asinine, and an interference engine at that.
                                If it was me, I would probably get something like this and change the timing set ASAP;
                                https://www.rockauto.com/en/moreinfo...sn=455&jsn=455
                                The prices are shockingly low too!
                                However, if David recommends a certain timing set for this era Buick V6, you would be wise to heed his advice.
                                That Sealed Power timing set is a good one. I know that on the newer Buick engines, there is a tensioner device as well. I am not sure if the 3.0 has this or not. If so, it goes on the front of the block under the timing cover, with a hard plastic "shoe" keeping the slack side of the chain from flailing and whipping. If you see this in the engine, it's important to replace it at the same time.

                                Also; thanks so much Jerry and to Ken (and others) for your vote of confidence in my advice. That means a lot and I really need / appreciate it at this time.

                                Sincerely,
                                David

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