What Should Gordo Do? - Page 2
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View Poll Results: What should Gordo do?

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  • Put the DCOE 9 back on and try tuning it before giving up.

    5 55.56%
  • Keep the DCOE152, give up, take it to a tuner.

    4 44.44%
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Thread: What Should Gordo Do?

  1. #21
    3000 Post Club Site Supporter P.J. Romano's Avatar
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    Idle and progression circuits are connected as the idle jet is responsible for the fuel supply to both circuits. Therefore the size of idle jets affects the transition circuit as well.
    Once the butterfly is fully open the motor is running on the main jet and air corrector jets, however when cruising at constant speed, the throttle valve is usually opened only partially, so the progression circuit is still engaged. That circuit is important for cruising performance as when transitioning from idle towards WOT. If the idle jet is too small or too large, it will cause the carburetor to go lean or too rich and the engine will stumble.

    DCOE carburetors came in a variety of types over the years. Variations include number of progression holes, pattern of progression holes, different floats, etc. The 152 type is the current commonly available new stock. It has many desirable features and excellent resistance to wear. One of good features is increased number of progression holes for smooth transition from idle.

    The fuel level is also important factor that affect the progression circuit. If memory serves me, you installed top cover from your old carburetor. The fuel level setting is NOT the same for DCOE 9 and DCOE 152, so that probably affected the engine negatively. I do not have exact information for DCOE 9 but for DCOE 152, fuel level should be 27 mm from the bottom.

    Also, I have always advocated against predetermined number of turns when setting up the idle mix screw. Idle mix screws came in several versions during the years. Later model DCOE Webers are fitted with narrow tapered screws that are more accurate and require more turns to flow the same amount as their predecessors. Therefore, the same number of turns is likely not valid for DCOE 9 and DCOE 152.

    Proper adjustment procedure is (Redline instruction):
    a. Start the engine, it will run slow and like a tractor. As long as it will stay running, the idle speed is not important at this point.
    b. First, turn in the mixture screw until the engine runs worse, then back out the screw ¼ turn at a time. The engine should start to smooth out. Continue to back the screw out ¼ turn at a time until the screw does nothing or runs worse. Then turn it back in to the point where it ran best. You want to tune the engine by sound. Adjust each mixture screw to the best, fastest and smoothest running point. Do this procedure with each mixture screw.
    c. Now you may adjust the Idle Speed Screw. It should be sensitive and only require ¼ turn in or out to achieve the idle speed you like.

    PLEASE forget about predetermined number of mix screw turns and adjust them to the point when the engine idle the smoothest. Changing the idle jets will require re-adjustment of mix screw.
    Last edited by P.J. Romano; 07-09-2019 at 01:12 PM.
    Old racers never die. They just go bench racing.

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  3. #22
    4,000 Post Club norbertone.gt371's Avatar
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    Quote Originally Posted by P.J. Romano View Post

    The fuel level is also important factor that affect the progression circuit. If memory serves me, you installed top cover from your old carburetor. The fuel level setting is NOT the same for DCOE 9 and DCOE 152, so that probably affected the engine negatively. I do not have exact information for DCOE 9 but for DCOE 152, fuel level should be 27 mm from the bottom.
    Oh yes,they are different. But its Chromie
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    Just Some Dude in Jersey The Scifi Guy's Avatar
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    The deed is done. The DCOE 9 is back on the car. With some help from my neighbor to nurse the pedal, I managed to stabilize the engine and I can now start it normally.

    Idle speed screw = About 1 turn out
    Mix screws = About 2.5-3 turns out
    Advance = About 30 degrees

    Except for the unknown advance degrees, the mix and idle screw turns are about the same as the tuner had them. High rev now sounds much cleaner. I'm going to pick up some new spark plugs tomorrow and work on fine tuning through the week, Amazonian jungle weather permitting. Charlie has booked a hotel near me for Friday night and then we'll go to the Deutsche Classic car show on Saturday. Unless a miracle happens, it's unlikely I'll take the GTX.

    Last edited by The Scifi Guy; 07-09-2019 at 07:45 PM.
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    Member guyopel's Avatar
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    I would like to suggest AC spark plugs R45TS taper seat . They seal great and you do not have the gaskets to deal with (gap according to your fire power) .035 to .040 if you have a HP coil or etc.
    Opel cylinder heads are cut for the taper plug seats.
    HTH
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    Quote Originally Posted by The Scifi Guy View Post
    Advance = About 30 degrees
    I can't help but ask: Is this the total of idle plus mechanical advance (i.e., revved to mid RPM's), or just the advance at idle?

  8. #26
    Just Some Dude in Jersey The Scifi Guy's Avatar
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    30 degrees at idle.

    I had to run the 152 in that range also.

    Boy, 30 degrees sounds high.

    I look at my plug wires at the diz cap and they look turned to far. It seems like I'm one tooth off with the dizzy. And the whole 30 degrees thing. But I asked PJ if being a tooth off could cause my timing light to read too high when the timing is set to good running and he said no. I recall this being correct: You can be one tooth or more off and still be set at perfect timing, but your dizzy will be rotated X # of degrees out of normal position.

    I only got it running stable at around 1200 and restartable without fuss and called it a day. I bought new longer bolts(2 were uncomfortably short) to hold the carb on and also bought a few "jam" nuts(skinny nuts for tightening against other nuts), plus new all-steel lock nuts. I didn't want the carb-manifold leak to ever happen again, so now those bolts are REALLY locked down to prevent unscrewing.

    It's gonna be really hot and humid all week, I don't know how motivated I'll be to work on it.


    Holy Schitt! I've been driving my Solstice to work the past few weeks and that means it gets parked outside the garage door when it's home. This morning at work,when I walked out to my car for a smoke break at 8am, I noticed that the nose of the car was all dirty with black stuff. Like REALLY dirty.

    Guess which car was 4 feet away from the GTX's exhaust these past 3 months while I was try to get the car to run right sitting on the lift?


  9. #27
    Can Opeler Knorm65's Avatar
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    If you measured your timing at 1200rpm. 30 degrees is high, but not as high as you think. My orange GT has 8 degrees static timing at 600 rpm, but my modified distributor kicks in 24 degrees by 1250rpm.

    My red GT has 26 degrees at 1250rpm with a similar curve and a different modified 1975 distributor. (this is 11 degrees at 650rpm and 36 degrees total by 2600rpm)

    64950500_463514727742494_3523964831793152_n.jpg

    I showed Rally Bob my curve and he said it was fine, but he would aim for more advance at idle! he said he aims for 18-22 degrees advance at idle, but he uses quite different engines than we do.

    Measure your advance at the lowest RPM you can get your engine to run. Even at 800 degrees you will have some mech advance with the smaller springs though.
    Last edited by Knorm65; 07-10-2019 at 11:06 AM.
    "Mira," 1970 Opel GT Working ARA AC, European 2.0L and Midikit
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  10. #28
    3000 Post Club Site Supporter P.J. Romano's Avatar
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    Gordon, you might still check the cam timing with Charlie. I can recall that you changed the chain tensioner at some point. Not likely but the chain might have jumped a tooth in the process.
    Old racers never die. They just go bench racing.

  11. #29
    Opeler jmbinjax's Avatar
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    Quote Originally Posted by The Scifi Guy View Post
    3
    Holy Schitt! I've been driving my Solstice to work the past few weeks and that means it gets parked outside the garage door when it's home. This morning at work,when I walked out to my car for a smoke break at 8am, I noticed that the nose of the car was all dirty with black stuff. Like REALLY dirty.

    Guess which car was 4 feet away from the GTX's exhaust these past 3 months while I was try to get the car to run right sitting on the lift?

    I've been wanting to say this for a while and others have already suggested it. A/F gauge can tell a lot. Yea, your butt has served you well for XX years. Has it??? Running good according to your butt doesn't mean it's running right. No offense intended but it seems you chase your tail a lot without using instruments.

  12. #30
    Senior Member The Cub's Avatar
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    On the timing thing, as long as the rotor is pointing to the correct cylinder weather your a tooth off is only relevant to having enough room to advance or retard regarding the canister etc. you just want it set up in the position that allows you plenty of room for that. I run the engine at 4000 RPMs and set my total, let it fall where it falls at idle. You’ve gone through your dizzy and it’s reliable. I think you said 28 was the total on your engine. If you can’t get it to idle you’ve got something else going on. PJ’s suggestion to check the cam timing wont hurt. Have Charlie bring a downdraft manifold (if it bolts on to your head) and a good 32/36 & some jets. Temporarily use this just to troubleshoot. If you cannot get a smooth idle with this simple basic set up then you know it’s not the carburetor. Just a thought.

  13. #31
    Opel Rallier since 1977
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    OK, on the idle timing being up around 30 degrees. And agreed as above on the rotor distributor position; it does not effect timing per se but only need to be close enough for the spark to the jump to the right spark tower, and with not too long an arc. Extreme misalignment can cause misfiring and crossfiring. (At least it is not as critical for crossfiring on a 4 cylinder vs an 8 cylinder.)

    Your know where this question on timing is heading: Too much total and then there is detonation under loading. I don't know your mechanical advance curve at all but 30 degrees initial sure caught my eye. It should not be any issue to raisee the revs to a few thousand RPM while sitting while watching timing; the engine is not under load sitting still, so detonation is not very likely.

    Again, just curious: What is your reference for 0* timing, and for other timing numbers? I have not followed things 100% here, but be aware that dialback types of timing lights can be wrong when used with multispark type ignition systems. Dunno if you have either of those things or not...

  14. #32
    4,000 Post Club norbertone.gt371's Avatar
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    Looking arround today and found this one here.A groundbase jet set for a 152 45 Weber at 2.4 Opel Engine.
    But its for DSD and not SSD.Scoll down for sizes.

    https://www.ebay.de/itm/Grundbed%C3%...53.m1438.l2649


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  15. #33
    Opeler jayhawkjesse33's Avatar
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    When I purchased my DCOE carbs from Pierce Manifolds, they asked for all engine information (displacement, compression, cam specs, etc) and provided carb jetting to meet those specs. It could be worth a call to them to see what they would suggest for your engine. You wouldn't have to buy anything, but it could give you insight on how close or far away your jetting may be.

  16. #34
    Just Some Dude in Jersey The Scifi Guy's Avatar
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    10 degrees mechanical advance
    Locked plate dizzy, no vac advance
    Split profile cam, fast opening/normal closing
    Multispark Pertronix
    Dial-type light
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  17. #35
    Just Some Dude in Jersey The Scifi Guy's Avatar
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    Quote Originally Posted by jmbinjax View Post
    Yea, your butt has served you well for XX years. Has it???
    YES, as a matter of fact it has! And PJ and many others who have been driving these cars for 40 years like I have. I didn't get 225,000 miles out of my last GT and be able to sell it with an engine that didn't smoke and ran like a kitten if it didn't.

    My present problem arose because I didn't understand how totally different a side draft behaves when it has a vacuum leak and I didn't know that you have to rejet when switching from a 45DCOE 9 to a 45DCOE 152.

  18. #36
    Senior Contributor GoldGT's Avatar
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    Wow. Between this thread and the Pissed thread you have gone nuts trying to figure out these carbs. A long time ago lots of people told me that trying to EFI my engine was too complicated. Seems to me that trying to carb your engine is more complicated than the EFI. Just fuel inject the sucker and get it over with!
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    Quote Originally Posted by The Scifi Guy View Post
    10 degrees mechanical advance
    Locked plate dizzy, no vac advance
    Split profile cam, fast opening/normal closing
    Multispark Pertronix
    Dial-type light
    OK, tnx... just wondering where the total advance is and when; don't want you to 'splode any pistons. I can't say if the light and Pertronix multi-spark 'like' each other or not. Plenty of info out there about incompatibilities found between MSD and dial-back.... just throwin' that on the 'food for thought' pile.....

    When things don't make sense, it is time to question all assumptions....I am going further and further 'back to basics' on our '75 EFI oddities as we sort that out.

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    Quote Originally Posted by Gary View Post
    It is amazing how much a vacuum gauge helps for troubleshooting carb/vacuum leaks/timing/valves issues. It has become a lost art!


    I just picked up the current edition of Hod Rod Magazine, which had a nice 8 page article on vacuum testing as a valuable and underused method. It has a big flow chart to help you with your diagnostics. As a bonus there is a picture of an Opel GT (junkyard style) in the current classics section, however it is not named like the three other cars on the same page, perhaps the author was unaware of what this cool looking old car was. I plan on keeping the magazine in my toolbox next to the vacuum gauge.

    FWIW I plan on installing an A/F gauge in my '73 to keep me out of the danger zone (detonation) since I will be trying to maximize power and efficiency.

  21. #39
    Just Some Dude in Jersey The Scifi Guy's Avatar
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    Quote Originally Posted by GoldGT View Post
    Wow. Between this thread and the Pissed thread you have gone nuts trying to figure out these carbs. A long time ago lots of people told me that trying to EFI my engine was too complicated. Seems to me that trying to carb your engine is more complicated than the EFI. Just fuel inject the sucker and get it over with!
    I'll be receiving a 2.2 with Motronic "someday" from Charlie. We'll see if I ever get around to installing it.

    Guys, understand that there are essentially zero comprehensive write ups about single side draft set ups. My 125 page Weber and Dellorto side draft book has about 4 scattered sentences about SSD's. My 400 page Haynes Weber Carburetor Manual doesn't mention them at all. None of them say that you can have a vicious vacuum leak and the car will start normally and run just fine at idle. I only found a one sentence mention that said that DCOE 9's are easier to tune than 152's because of the extra/different progression holes and that DCOE 9'ers simply run their set ups a little richer. That's it. I only found the last sentence this past week.

    But then consider how much is written about DUAL side drafts. Hundreds of pages of info and detailed information and charts for all sorts of different engines.

    And then consider that my set up is for low speed daily driving a stroker engine in a city with a single side draft and an automatic on a car with a limited gear range and an intake manifold with one runner 3 times longer than the other one and a split profile cam that lifts very quickly, but closes slowly/normally. Go ahead, tell me what the timing and fuel mix should be on a set up like that.

    I'm virtually certain that my whole problem was a small vacuum leak that would only manifest itself when the engine warmed up. The default limp mode feature in side drafts may have masked the leak at start up. The very rapid response of side drafts to rpms and throttle, plus the leak only happening to one runner/two cylinders, may have also masked the leak and gave me the false indication that my ignition turned off when my engine would be idling in the driveway for 20 minutes perfectly and then abruptly turn off or suffer bouts of stumbling. Wait 2 minutes and everything back to normal. My engine was the envy of the Opel world. How many Opelers can walk up to their cold engined car, at any time of year, and just reach in the window and turn the key to start it? Not many.

    Assuming I'm right about the vac leak and the symptoms fooling me and every other Opeler and engine expert I talked to or who chimed in on the subject in various forums, any engine dude will tell you that a smooth running engine that just turns off without warning has an electrical/ignition issue. Most will also say that a stumbling engine is caused by fuel delivery or vacuum leaks. What do almost all Opels do when they have a vacuum leak? They are usually hard to start and have erratic idle. My engine started like I had a Saturn rocket booster under the hood and idled like a dream for 3 years. Then I had my recent problem and followed all the wrong paths and then tried a replacement carb that, although the same size and same manufacturer and the same jetting and set up, refused to run properly or use the same settings as the previous carb, all because it has a couple of extra pin holes in the barrels.

    Last edited by The Scifi Guy; 07-10-2019 at 04:44 PM.
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    3000 Post Club Site Supporter P.J. Romano's Avatar
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    Quote Originally Posted by GoldGT View Post
    Wow. Between this thread and the Pissed thread you have gone nuts trying to figure out these carbs. A long time ago lots of people told me that trying to EFI my engine was too complicated. Seems to me that trying to carb your engine is more complicated than the EFI. Just fuel inject the sucker and get it over with!
    This is because he is missing one carburetor.
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