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Thread: Tuning help needed - '91 TBI 383 w/ Vortec heads

  1. #31
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    Quote Originally Posted by donf View Post
    There are different ways to end up with different results. Look at the voltage shape of the typical narrow band o2 sensor. You may be able to get you block learn dialed in and its fine for that, but what about your WOT mixture that's not suppose to be Stoic?? After all you have put into you project do you really want to skimp with $160 and a few wires to log the data? If money is that tight, sell it on craiglist when you are done. No one will ever say a narrow band is superior for tuning, you may be able to "get by" but really for the money involved, why? I did not want to bother with mounting a gauge or cutting holes so the new AEM line has one that just data logs to a computer. The accuracy is very close to the big $$ Haltech setup on my chassis dyno.

    Attachment 14167
    I get it that WB is superior for tuning outside of closed loop. Not arguing and, no, money is not that tight. I just haven't gotten to it yet. I have other projects and I stagger the time and $$ I put into all of them. Suburban is drivable as is so it's not number one priority. Am looking around online for a WB kit, but in the meantime I don't see the harm in spending $15 on a new MAP to see if I can rule that out, same with forcing it into open loop and taking a short test drive. I'm still concerned I have some unresolved mechanical issues, too.

    So some beginner questions on WB.... You mention you're not using a gauge and just a single wire into a computer? How does that work, is it a USB? Does it sync with the log file from the ALDL/ECM output? If not how would you reference it back to time-based events like a throttle stab?

  2. #32
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    Quote Originally Posted by Kitch View Post
    Have you blended your main and idle spark tables in the areas where they crossover (I'm assuming you have tracing turned on)?
    Thanks, no, I have not been using tracing. But I just read the help section in TP on that and I'm definitely going to start using that feature, assuming I can get it to work. Sounds like the ADX and XDF have to have values linked between them - not sure if the ones I've been using have that.

  3. #33
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    I have my sensor wired into the ecm. The instructions are the same for logging even though there is no gauge. Its important that you download the zip and follow ALL the instructions. I have had several people here contact me privately saying their wide band is not working. I ask them to follow the instructions listed in the zip file and never hear from them again. Ha ha. I think people just think its hooking up a wire and your done. I also had to redo some of the adx file. The A217 OD file has some quirks. Some stuff led me to change things and now I like it better. One peeve is they have extra data points that look cool for the fuel table but have no value as the bin does not have those same points. I kept getting data from the useless columns/cells mixed up with the ones I needed. Now my ADX does not have those!

  4. #34
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    Quote Originally Posted by donf View Post
    I have my sensor wired into the ecm. The instructions are the same for logging even though there is no gauge. Its important that you download the zip and follow ALL the instructions. I have had several people here contact me privately saying their wide band is not working. I ask them to follow the instructions listed in the zip file and never hear from them again. Ha ha. I think people just think its hooking up a wire and your done. I also had to redo some of the adx file. The A217 OD file has some quirks. Some stuff led me to change things and now I like it better. One peeve is they have extra data points that look cool for the fuel table but have no value as the bin does not have those same points. I kept getting data from the useless columns/cells mixed up with the ones I needed. Now my ADX does not have those!
    Thanks for the great info. Unfortunately, my project has hit a major mechanical stumbling block - my new 383 seems to be using significant oil. And it's not going on the ground. The only explanation I have is that I have the wrong oil rings or they didn't seat correctly. I haven't talked to the machinist yet that did the work (I assembled) but I'm guessing I'm going to have to pull the motor and tear it down. Obviously tuning will go on hold if all this is accurate.

  5. #35
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    Quote Originally Posted by Daveo91 View Post
    Thanks for the great info. Unfortunately, my project has hit a major mechanical stumbling block - my new 383 seems to be using significant oil. And it's not going on the ground. The only explanation I have is that I have the wrong oil rings or they didn't seat correctly. I haven't talked to the machinist yet that did the work (I assembled) but I'm guessing I'm going to have to pull the motor and tear it down. Obviously tuning will go on hold if all this is accurate.
    Thats too bad. It has to be disappointing.

  6. #36
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    Bummer - hope it's something simple like the rings' gaps lined up in a row vertically (I've seen it before).

  7. #37
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    Quote Originally Posted by PlayingWithTBI View Post
    Bummer - hope it's something simple like the rings' gaps lined up in a row vertically (I've seen it before).
    Thanks to both of you. Yeah, Iíve been hoping for something simple for a while now, have actually been in denial. But I canít deny 1/3 to 1/2 quart in 300 miles any longer. Funny thing is plugs do not look oil fouled to me at all, and the (hot) compression is good and consistent in all cylinders (approx 180 at three hits and 200-210 at five hits). And there are not clouds of smoke going down the road, even when I get on it with high load. It will puff smoke if I gun it at idle, though.

    As for ring install, I followed the instructions that came with the Hastings rings to a T. Thereís a backstory tho: I had to switch machinists mid-build. The first one was hitting the sauce pretty hard and he had about five missed deadlines. He also bought pistons that would have given me 10:1 CR with vortec heads. So I found a new machinist and bought some KB pistons that lower my CR half a point. Second guy, who has a good rep building high end motors, said the rings would be fine with the new pistons but now I have some doubts.
    7C1153E7-6C07-446A-8F23-5B702E61D86C.jpg17A07925-4A18-4A12-B9BE-B7D27B20DE57.jpg

  8. #38
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    Some rings take a different grit hone. Its possible if between the two machinists, the wrong grit was used the rings may take longer to seat or may not seat at all. The plugs look really good, so not a lot of oil is getting in there. I made the mistake of ordering Jegs crappy vortec heads, the guide seals leak even with under a 1000 miles on them. i will have to tear them down this winter.

  9. #39
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    Quote Originally Posted by donf View Post
    Some rings take a different grit hone. Its possible if between the two machinists, the wrong grit was used the rings may take longer to seat or may not seat at all. The plugs look really good, so not a lot of oil is getting in there. I made the mistake of ordering Jegs crappy vortec heads, the guide seals leak even with under a 1000 miles on them. i will have to tear them down this winter.
    Thanks for the info. I know there was something with the hone. The first guy did his own, but I know the final machinist did a cross-hatch hone too. He didn’t want to rely on the other guy’s work. I’m going to change the oil one more time and see if that helps. Initial start up and first few hundred miles were on conventional oil (Chevron Delo, I think) but then I went to Mobil 1 synthetic. Sounds like there’s at least a possibility that’s making things worse. I’m going back to probably Shell Rotella, put a couple hundred miles on it and see if there’s improvement. Also ordered a new AC Delco PCV valve tonight - just in case the parts store one in there now is adding to the problem.

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    how are you breaking in the engine? with a flat or hydraulic tappet cam, after initial break in i will dump the oil, but why are you changing oil after a few hundred miles? i normally goto a "normal" oil change interval and just add oil to make sure it stays at full until next oil change. i would do at least 2 normal OCIs befote switching to synthetic, but that's me. im also a fan of "beating on it" vs the old school way of driving like grandma.

  11. #41
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    Quote Originally Posted by tayto View Post
    how are you breaking in the engine? with a flat or hydraulic tappet cam, after initial break in i will dump the oil, but why are you changing oil after a few hundred miles? i normally goto a "normal" oil change interval and just add oil to make sure it stays at full until next oil change. i would do at least 2 normal OCIs befote switching to synthetic, but that's me. im also a fan of "beating on it" vs the old school way of driving like grandma.
    I am a little different. For my roller cam small blocks. Mobil One in the pan, prime the system with a drill and priming tool, then start it up. Run it at 2,500 rpm long enough to get it warm and shut it off. Check it over for leaks, loose bolts, etc. Then take it out and beat the absolute crap out of it from the first stop sign. At 60K on the short block I used 1 qt over 2,200 miles and much of that was 75-90 mph. I am not even sure it was all the rings fault even. The valve seals were also a bit hardened and the front crank seal had a seep at the time as well.

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    Quote Originally Posted by Daveo91 View Post
    Thanks for the info. I know there was something with the hone. The first guy did his own, but I know the final machinist did a cross-hatch hone too. He didn’t want to rely on the other guy’s work. I’m going to change the oil one more time and see if that helps. Initial start up and first few hundred miles were on conventional oil (Chevron Delo, I think) but then I went to Mobil 1 synthetic. Sounds like there’s at least a possibility that’s making things worse. I’m going back to probably Shell Rotella, put a couple hundred miles on it and see if there’s improvement. Also ordered a new AC Delco PCV valve tonight - just in case the parts store one in there now is adding to the problem.
    Sounds like a good plan. I use to work in front of a machine shop. I had to do their R&R's sometimes when things went wrong. The big thing that got them over and over was hone grit. They would get in a hurry and just hone it with what ever they thought was standard. Different brands and ring types will tell you what grit to hone the cylinders. As far as beating on it, vs not I really don't think that makes the difference compared to having a machinist who reads and follows the ring manufactures instructions. Some cylinder pressure behind the rings though will push them out against the walls harder. I do think if your rings have not fully seated, switching to conventional oil may help. It doesn't even have to be the good stuff if you do not have a flat tappet cam. If it does, one with zinc will help.

  13. #43
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    I bought an 84 Dodge (new in 84) W150 with a 360 4BBL, it burned about a qt/1000 miles for about a year. 1 day it wouldn't start (turns out the distributor reluctor was bad), after cranking forever it finally started. I drove it home 15 miles with almost no oil pressure. I wound up sucking about a gallon of gas into the crankcase. After changing the oil and distributor it ran great and didn't burn a drop of oil. LOL. I drove it hard including pulling goose neck trailers for 206,000 miles before rebuilding it.

  14. #44
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    Quote Originally Posted by tayto View Post
    how are you breaking in the engine? with a flat or hydraulic tappet cam, after initial break in i will dump the oil, but why are you changing oil after a few hundred miles? i normally goto a "normal" oil change interval and just add oil to make sure it stays at full until next oil change. i would do at least 2 normal OCIs befote switching to synthetic, but that's me. im also a fan of "beating on it" vs the old school way of driving like grandma.
    It's a roller cam, stock L31 to be exact. I really didn't break it in. Everything I read said I didn't need to. But first start up was on an engine stand with a carb, radiator and water pump not hooked up. I had water in the block, but it wasn't circulating and I only ran it for a minute or two at a time and didn't take it much past idle. Really hoping that's not the cause of all this. Even when I got the motor in I didn't run it real hard at first. Wish I would have now, but I was also worried about the tune and having it run too lean. Since then I've definitely taken some hard pulls on it with high load, but perhaps it was too late. I changed oil because I eliminated the factory oil cooler (wanted to rule that out as cause of oil loss) and also wanted to check for any metal on the magnetic drain plug. (only a light fuzz)

  15. #45
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    Quote Originally Posted by donf View Post
    Sounds like a good plan. I use to work in front of a machine shop. I had to do their R&R's sometimes when things went wrong. The big thing that got them over and over was hone grit. They would get in a hurry and just hone it with what ever they thought was standard. Different brands and ring types will tell you what grit to hone the cylinders. As far as beating on it, vs not I really don't think that makes the difference compared to having a machinist who reads and follows the ring manufactures instructions. Some cylinder pressure behind the rings though will push them out against the walls harder. I do think if your rings have not fully seated, switching to conventional oil may help. It doesn't even have to be the good stuff if you do not have a flat tappet cam. If it does, one with zinc will help.
    Thanks for the confirmation. Yeah, it's a roller cam so no need for high zinc oil, but Shell Rotella seems to be a good heavy duty oil from stuff I've read. There is some debate if it will cause premature cat failure (I'm running a cat) but I gotta resolve the oil consumption problem and then I'll worry about my cat!

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