Difficulty starting a fresh rebuilt engine
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Thread: Difficulty starting a fresh rebuilt engine

  1. #1
    3000 Post Club m610's Avatar
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    Difficulty starting a fresh rebuilt engine

    I posted something about this in other threads, but the problem persists so I figure best to start anew.

    The engine is a 1.9, low compression. I assembled it and ran it on a test stand last summer. It ran great. I put it under a tarp until last week when it was time to put it in a car. I opened it up to check for rust and everything was good. Just a few spots on the valve cover.

    So now it is in the car and I am having a devil of a time getting it to run. Initially it would start and would rev up to 2000-2500 rpm, then die, on starter fluid. Later I tried dribbling gas in and I got the same result. First suspect, fuel, so I drained the fuel lines and ran a hose to a gas can. No improvement. I removed and reinspected the carburetor (32/36). No change.

    The crazy revving suggested a vacuum leak so I plugged the vacuum advance ports. After that I was able to start the car without starter fluid or a dribble of gas, but it would backfire (out the carb) like crazy, and would not idle.

    I double and triple-checked the firing order. 1-3-4-2.

    Sticking valve? I removed the valve cover. All valves go up and down. I ran compression tests (cold) and got 140 +/- on all four.

    One by one I removed a spark plug wire and cranked, and the symptoms did not change. I was hoping that for some reason one cylinder was causing these problems. Nope. All of them do it.

    This sounds like a timing issue. I verified ignition timing: needle on the ball, mark on the crank pulley, rotor pointing to 4 o'clock, rockers for #1 loose. I cranked it around and checked cam timing. Again, needle on the ball, mark on the crank pulley, rotor pointing to 10 o'clock. The dowel pin was at the top and using a metal ruler I could draw a straight line between the center of the cam, the mark on the cam sprocket, and the notch on the little hickey under the cam sprocket. Cam timing is good.

    If I advance the ignition 20-30 degrees the car will start and not backfire, but it runs rough and won't idle.

    Other than pulling the distributor and checking it out, which I will do after lunch, I am out of ideas.

    Mike

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  3. #2
    Über Genius First opel 1981's Avatar
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    Did you disconnect the brake booster and plug that port?
    Opel GTs are not GM products
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—
    Humans are not an endangered species!
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—

  4. #3
    3000 Post Club m610's Avatar
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    It's a new brake booster, but I'll get out my Mity-Vac tomorrow to see if it can hold a vacuum.

    Mike

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    Über Genius First opel 1981's Avatar
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    Quote Originally Posted by m610 View Post
    It's a new brake booster, but I'll get out my Mity-Vac tomorrow to see if it can hold a vacuum.

    Mike
    On mine, I chased ghosts til I found out the hose was cracked. That's where I was going with my thoughts on the booster port. Closing the port at the manifold isolates everything booster related.
    Opel GTs are not GM products
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—
    Humans are not an endangered species!
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—

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    Detritus Maximus opelbits's Avatar
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    Last time I had a problem with the rpm shooting up it was because of a messed up throttle linkage not allowing the primary butterfly to close. The nut holding things together at the carb backed off and would allow further opening but not closing all the way.
    "No, it's not fiberglass."
    "No, the motor is not in the back."
    "No, your friend in high school did not 'peg' his speedometer."

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    3000 Post Club m610's Avatar
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    I removed and cleaned the distributor. The advance plates were gummed up. Not stuck, but not easy to move.

    I can't find points and condenser locally so I put them back in.

    I checked timing again. Everything checks out.

    Other than a timing issue it could be a lean mixture issue. Lean will backfire (carburetor), rich will afterfire (exhaust). So I tried started fluid again and the car started and ran for a few seconds, with no backfires.

    The fuel lines are clear and the filter is new. I'm going too swap the carburetor for the Tinyvette's original 32/36.

    Wish me luck.

    Mike

  9. #7
    3000 Post Club m610's Avatar
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    I swapped the carburetor. No difference.

    The engine starts and runs smoothly using starter fluid so I am still suspecting the fuel system. The rain finally hit so work is off for the day. (Too many race cars in the garage!)

    Mike

  10. #8
    3000 Post Club m610's Avatar
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    Quote Originally Posted by First opel 1981 View Post
    On mine, I chased ghosts til I found out the hose was cracked. That's where I was going with my thoughts on the booster port. Closing the port at the manifold isolates everything booster related.
    Using my Mityvac I pulled about 13 mm Hg vacuum on the booster hose and it held solid.

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    Bikini Inspector Frozen Tundra GT's Avatar
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    Quote Originally Posted by m610 View Post
    I swapped the carburetor. No difference.

    The engine starts and runs smoothly using starter fluid so I am still suspecting the fuel system. The rain finally hit so work is off for the day. (Too many race cars in the garage!)

    Mike
    setup a makeshift fuel supply, funnel with hose attached and see if it runs for longer...
    m610 likes this.

  12. #10
    Über Genius First opel 1981's Avatar
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    Why couldn't you find points and a condenser locally? Just ask for them for a 72 VW beetle.
    Opel GTs are not GM products
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—
    Humans are not an endangered species!
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—

  13. #11
    Detroit,where my home was 2 Fast 4 U's Avatar
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    With a faulty capacitor the engine won't run nice either.
    Maybe a faulty gas pump? [if you use the stock one on the engine]
    Last edited by 2 Fast 4 U; 3 Days Ago at 04:01 AM.
    Opel Ascona;
    Only built from 1970 - 1975




    Understeer: The front of the car hits the wall,
    Oversteer: The rear of the car hits the wall,
    Horsepower: How fast the car hits the wall,
    Torque: How far the car pushes the wall.

  14. #12
    3000 Post Club m610's Avatar
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    I'll swap the cap. I have old spares around. They probably work.

    Fuel pressure is just a touch past 1 psi. The car has a new electric pump from OGTS. I'd think it would be putting out something closer to 3 psi.

    I'm heading to the hardware store now to get a couple of hose fittings that I can use to connect a gravity-fed fuel system.

    Wish me luck, and that the rains stay away a little longer.

    Mike

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    Member Dmcbrass's Avatar
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    Quote Originally Posted by m610 View Post
    I'll swap the cap. I have old spares around. They probably work.

    Fuel pressure is just a touch past 1 psi. The car has a new electric pump from OGTS. I'd think it would be putting out something closer to 3 psi.

    I'm heading to the hardware store now to get a couple of hose fittings that I can use to connect a gravity-fed fuel system.

    Wish me luck, and that the rains stay away a little longer.

    Mike
    1 PSI is too low. Weber Carbs need closer to 2 PSI. You need to refrain from using starting fluid. It washes the cylinders of oil causing cylinder scoring.

  16. #14
    Opeler
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    Seems like a vacuum leak to me. For sure cap all vacuum ports and if you can use a smoke tester or other method to check your manifold seal that might be telling. If you have a timing light check the timing while cranking just to see if it's hitting close.

  17. #15
    3000 Post Club m610's Avatar
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    This appears to be the pump OGTS sells.

    Link: https://www.pegasusautoracing.com/pr...asp?RecID=9616

    Pressures of 1.5 to 4 psi are normal. I'm getting 1.5 psi at the pump.

    Mike

  18. #16
    3000 Post Club m610's Avatar
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    Nothing has worked.

    Only by putting in a ton of distributor advance can I get it to run without backfiring, and even then it runs rough and will not run at low RPM.

    I'm down to two possibilities, that I can think of. One is a bad condenser, and the other the distributor grounding.

    What I've read about a bad condenser closely matches what I have been experiencing. There a long thread on Ford Barn that describes on guy's plight and the solution.

    The other possibility is the grounding of the distributor itself. How is it normally grounded? Through the fork that keeps it from turning? The one I am using is painted. Maybe I should scratch off some of the paint.

    Maybe it is true what they say, that 95% of all carburetor problems are electrical.

    Mike

  19. #17
    Bikini Inspector Frozen Tundra GT's Avatar
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    grounded through the mount and touching the block. some say remove the gasket.

    all those parts and not another condenser? clean your points too.

  20. #18
    3000 Post Club m610's Avatar
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    I have a backup distributor for the Tinyvette. I almost don't want to try it. Don't need another disappointment.

    Mike

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    Über Genius First opel 1981's Avatar
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    You can use a cheap ohmmeter from Harbor freight to check grounds.
    Opel GTs are not GM products
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—
    Humans are not an endangered species!
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—

  22. #20
    3000 Post Club m610's Avatar
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    The distributor ground is good. It just occurred to me that that was something I had always taken for granted.

    I rummaged through my parts bin and found a condenser, put it on, no difference. Maybe it was bad?

    This is driving me nuts. A whole week.

    As if I had not checked a dozen times before I cranked the motor around to where the ball is under the needle and the rotor is pointing at #4 and the cam is in the correct position, dowel straight up, straight line between the center, dot, and mark. Plug wires are going to the right plugs.

    I tried different fuel sources and I swapped in a good carburetor. Maybe I should swap in the Tinyvett'e distributor. (My spare distributor is in the wagon, and the Tinyvette uses a Petronix.)

    Mike

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