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Technical Chevy 235 Distributor questions

Discussion in 'The Hokey Ass Message Board' started by 4doorsformorewhores, Aug 3, 2021.

  1. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    Hadn’t tried that yet, but I can today. Anything to look out for when I do?
     
  2. I’m trying to find a good video for ya

    this one cuts off before its done. Dang it
     
    Last edited: Aug 4, 2021
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  3. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    Very helpful though, thank you. I have a little chart similar to the readings they were going over. All in all if a gauge hooked to my wiper port on the intake manifold reads at a pretty steady 20 I’m hopeful I can eliminate vac leaks. So maybe the next step is fuel system. Chevs of the 40s sells a rebuilt Rochester for a reasonable price, may try and new carb and work my way back from there. Side note, fuel pump is only a few months old as well
     
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  4. My uncle could diagnose an engine with a vacuum gauge and a stethoscope, unfortunately my teenage mind didnt pay a lot of attention. I’m just smart enough to be dangerous. But I had issues with my 235. Most were carb and ignition problems.
    a bad ballast resistor killing points, a dead coil, bad ground wire, stopped up carb.
    The carbs on these are very simple. You might enjoy trying to rebuild.
    The more you learn, the more mental tools you have.
     
    Last edited: Aug 4, 2021
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  5. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    Carbs are something you can work on. They are not magic black boxes that have to be replaced at the first hint of trouble.
     
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  6. Says who? LOL. Yep , pretty simple to be so complicated. Just a "controlled" gas leak,/squitter.:p:p

    Ben
     
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  8. Truck64
    Joined: Oct 18, 2015
    Posts: 5,325

    Truck64
    Member
    from Ioway

    When I started working on my stuff I made the exact same mistakes everybody else does.

    Look at any chapter on a Tune-Up in Motors, Chiltons, or shop manual. They are all the same, because engineers hashed this out by about 1915, and despite all the advances since then it hasn't really changed, there's just more shit in the way of making an accurate diagnosis. In fact, if you read those old manuals from the 1920s you might even learn something. Today's "technicians" are taught only to read codes. There are some good things about this, but it is no substitute for a mechanic someone who has both experience and is observant, and has a logical mind.

    Anyhoo notice what the steps are in a Tune-Up or Troubleshooting - and it ain't ever Step 1. "Replace Carburetor"!!

    It's always a Compression Test, which can determine whether an engine is worth a Tune-Up in the first place. It's also independent of ignition or fuel. Next steps involve Ignition. Fuel is last.
     
  9. 6sally6
    Joined: Feb 16, 2014
    Posts: 2,459

    6sally6
    Member

    No familiar (at ALL...its a Shivel-lay:rolleyes:) with this engine but, have you tried to just give it a few more degrees of initial timing and re-set idle?!
    Sounds like some of the "stuff" I have encountered and more timing usually hepped
    6sally6
     
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  10. carbking
    Joined: Dec 20, 2008
    Posts: 3,715

    carbking
    Member

    Would suggest a re-read of Truck64's comment (post 40).

    When there is an issue, the best way to spend money, and NOT fix the issue is to guess ;)

    (1) compression test
    (2) ignition test
    (3) fuel system

    There is a reason for the order. If the compression is bad, you can buy the very best ignition system and carburetor or efi ever built; and the issue will still be present.

    If the ignition system is bad, then no carburetor or efi will fix the issue.

    The fuel system is last, because it depends on the other systems being in good condition.

    I read your comments about your ignition system. If you bought new components that were made in a country with 5 letters in its name, starting with a "C" (not Chile), your ignition system MAY be up to spec, but you don't know this! What you do know is that you have new parts. Ignition systems should always be checked with instruments.

    If you do not already have them, used quality test instruments may be obtained for not a lot of money (check Ebay, and look at the vendor's feedback rating BEFORE looking at the price).

    There are many really knowledgeable individuals that post on the site; but Dr. Werner Von Braun once stated that "one test is worth 1000 expert opinions".

    Learning, and fixing problems is part of the fun of playing with older vehicles!

    Jon.
     
  11. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    y'all are right, I know. I was always told to pinpoint issues before throwing parts at her, and step back and breathe a bit, but this one has eluded me for quite some time now, and I think I got impatient and just really wanted to drive my car again:mad: yesterday after I finally got a little time off of work I was able to tinker around a bit and give it a few small tweaks here, and a few there, testing driving it after each one and it ran pretty smooth! Didn’t die on me on the way home today, but it still had the bucking or momentary loss of power when picking up acceleration on the freeway. Two or three bucks, and she’s off to the races. I’m really leaning towards carb float here, because it tends to happen on a short but somewhat steep up and down part of the freeway
     
  12. Put a Carter electric Rotor Fuel Pump on it & you will love It.!
    You mount the Pump in the Back of the Car near the Gas Tank.
    Just my 3./5 cents

    Live Learn & Die a Fool
     
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 55,942

    squirrel
    Member

    A couple questions related to Jon's great post above...

    1. What is the dwell? You need a dwell meter to check this, and dwell meters are getting harder to find. Yard sales seem to be the best source.

    2. What is the timing? You need a timing light to check this. And be able to see the pointer and ball, near the starter.

    Just trying to get you back to basics.
     
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  14. My uncle used to buy a lot of cars. Most were cars that the previous owner gave up on. They would have lots of new parts on em.
    Points, coils, caps, wires.......
    His go to diagnostic tools were a compression gauge, vacuum gauge, stethoscope, voltage meter(no test light), timing light, oil pressure gauge and a Chiltons manual.
    He’d find distributors 180 out, broke wires, burnt valves, even simple stuff like the wrong firing order. Even a stopped up exhaust once.
    I bought a 472 caddy that the previous owner had replaced plugs, wires, coil, ignition parts chasing a problem. Got frustrated and sold the car.
    We put the engine on our run stand. Ran like crap. Good compression, oil pressure but vacuum was slightly suspect.
    The vacuum indicated a possible timing issue. Previous owner had been monkeying around with the distributor. Started messing with the timing, located top dead center, check the distributor and got the timing light out. Ran better but still not there.
    Our mechanic instructor was using this as a teaching moment for students. His experience kept having him believe it was timing related. Removed the water pump and timing cover, the cam sprocket was shot. Fiber gear had worn into the aluminum.
    Moral of the story:
    Every engine issue has a cause, sometimes multiple. Establishing a base line and working in a logical sequence either eliminates possibilities or illuminates problems.
     
    Last edited: Aug 5, 2021
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  15. trvguy
    Joined: Apr 12, 2010
    Posts: 94

    trvguy
    Member

    i've had a lean carb do this
     
  16. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 772

    MAD MIKE
    Member
    from 94577

    Funny, one of my quick checks when checking a car/engine is to see how sloppy the timing chain is. Usually note what the timing is, if it is off a bit rather than change the ignition timing I check the camshaft timing.
    Put engine to TDC(0°) pull distributor cap off.
    Manually rotate engine backwards while watching the distributor rotor, stop when it begins to move.
    Look at the timing marks.
    <5° Timing is OK
    <10° Timing is out, time to start looking for a new timing chaing/gear setup.
    >10° Nothing you are going to do is gonna fix the engines running, get a new timing setup.

    Lot of '70s-80s V8s have a hard time passing smog. Owner will throw all sorts of parts at it. Do the above check and I've found the cam timing to be out as much as 20° :eek:

    Flat link timing chains stretch and the misalignment of the link teeth digs into the nylon coated cam sprocket. That fails and the chain starts to eat into the sprocket, if its aluminum that will only last til the chain slips and the engine will no longer run. On iron sprockets it lasts a bit longer.
    It's amazing how much better an engine idles when the camshaft is functioning in the same time zone as the pistons.
     
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  17. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    Dwell is set to roughly 36 off the meter. Slightly out of spec, but nothing major. Timing (based on light) is slightly advanced, maybe 1/4” past the point, or to the left of the pointer, advanced. After the resistor when In I read high 5s-low 6s going to the coil. Vac ready steady at 20 at idle. Tach shows 600rpms at idle which I know is high, but when I bring it closer to 5 or sounds like it’s going to die. I tweaked the air fuel screw the other day with a vac gauge hooked up little bit little letting her catch her breath in between 1/4 turns and it smoothed out a bit. Test drive felt pretty good. Tach still bounces around when applying throttle from a dead stop (only time) and it did the bucking in the same exact on ramp on the freeway, but I think we may be headed in the right direction. For my sanity I hope at least
     
  18. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    Little update on what I hope to be forward progress, so maybe y’all can shed some insight for me. New carb came, but before bolting it on a decided to try and tinker with the one already on and figure it out. With the old carb still on I tweaked the air fuel mix a bit after pulling a few plugs that looked a little lean to me, and she stopped bucking on that same on ramp on the freeway. I richened the mixture quiet a bit about 3/4 turn if not more. She did however seem to fall on her face when accelerating here and there and died once the next day after down shifting from 3rd to 2nd and slowing down to make a turn. Got home and pulled one of the plugs again and it was pretty sooty. So I turned the mixture screw in another 1/4 turn today and have been driving it around. She seems ok, but not there yet. Still tends to fall on her face shifting from 1st to 2nd but not so bad from a dead stop in first. Could it be that richen the mixture is maybe just compensating for the carb sucking too much air from somewhere. Vac gauge reads steady at idle, so I’m not sure a leak is present. I feel like I’m in the right direction here, but something still isn’t quite right
     
  19. scoop
    Joined: Jul 4, 2001
    Posts: 1,463

    scoop
    Member

    Rochester 1 bbl?
     
  20. scoop
    Joined: Jul 4, 2001
    Posts: 1,463

    scoop
    Member

    I got two of them from parts stores that where rebuilt all didn't work right. One of them the main jet fell out.
     
  21. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    Yes sir
     
  22. 4doorsformorewhores
    Joined: Jul 7, 2021
    Posts: 61

    4doorsformorewhores
    Member

    PO said it was rebuilt, and it’s ran tits for 6 months or so, but it’s acting up lately. And tuning this little guy is like picking a safe, slow as steady
     

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