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196 Dieseling, now no-start

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tungsten View Drop Down
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    Posted: Jan/22/2022 at 11:15am
My ‘63 550 has had a high-idle issue, causing dieseling, lately but yesterday was the worst it had ever been. Which led immediately into a no-start condition. 

Before I start worrying about cracked blocks and heads, where should I start diagnosis?  The engine almost catches, but it feels like it may have jumped time. Is that even possible?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 11:59am
It could have jumped time, but with steel timing gears/chain (as opposed to nylon gears which were common in the later 60's and 70's), it's not real likely.

Research how to find Top Dead Center on cylinder 1. Find out if the distributor rotor is in line with number 1 terminal on the cap and wire. And then see if the timing mark on the vibration dampener lines up. Do you know how to use a timing light?

Also, check point gap, as point gap and functionality also impacts timing. Make sure the 'rub' block on the point set didn't fall off or wear out.

If you had high idle, and then dieseling, you also had a bunch of raw gas going into the cylinders. So it could just be flooded, and plugs could be fouled. Dieseling is partly a carburetor issue, and partly a function of how much carbon has built up in the cylinders (to produce a hot spot for ignition.)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 12:14pm
Almost catches?  Could be a bad condenser.   But you need to fix the dieseling and I bet if you fix the high idle.... it will fix everything else
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 1:04pm
High idle
 Doees the choke butterfly operate?

Is the fast idle cam stuck?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pacerman Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 1:55pm
You need to keep the air out of the engine to stop the dieseling.  Make sure the throttle plate goes all the way to the idle setting when you let off the gas.  Look for vacuum leaks.  If your old carb has high mileage the throttle shaft bushings could be work allowing a vacuum leak through the base of the carb.  Joe
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tungsten Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 3:37pm
Good news!  It was just flooded. I pulled the plugs to let the chambers evaporate and she just fired right up. 

Now onto the idle issue…
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wittsend Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 8:01pm
Your high idle is likely a misadjusted carburetor choke. As mentioned when the car is cold and the choke active there is a stepped piece of linkage that increases the idle speed. As the carburetor warms up the choke begins opening up and the idle drops into lesser steps to lower the idle speed. Eventually the steps move to a point they are no longer active and the main idle adjustment becomes the active setting once the car is at normal temperature.

If the choke is misadjusted it may be remaining on one of the steps creating both a high idle AND a rich condition that can cause the car to diesel when the ignition is turned off.

A too high float adjustment can also contribute to dieseling because gas is splashing into the carburetor.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/22/2022 at 8:03pm
What's this car and engine's history? Recent find? Daily driver? Restoration?

Is the carb a sticky smelly mess? Recently rebuilt engine? Old survivor?

First Principles is the way to go. Everyone's advice here is in line with that. Make sure basic timing is close enough. If that's OK or close, I smell carb issues. high idle? Do you have a vacuum leak? Ported vacuum to the distributor? 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote tungsten Quote  Post ReplyReply Direct Link To This Post Posted: Jan/23/2022 at 10:18am
Originally posted by tomj tomj wrote:

What's this car and engine's history? Recent find? Daily driver? Restoration?

Is the carb a sticky smelly mess? Recently rebuilt engine? Old survivor?


It's a survivor that I'm trying to put more into daily service.  Picked up from Bring a Trailer a couple years ago, previously owned (and written about by!) automotive journalist Jamie Kitman, given a once-over and some general repairs by Frank.

I've put a Daytona rebuild kit into the carb, the engine has been lightly rebuilt, and all of the ignition components are up to par.  I suspect the engine builder just cranked up the idle stop screw to fix an issue with a deceleration stall, before the really high idle it was getting stuck on fast cam pretty often when coming to a stop.

I also think my throttle linkage is binding up in a more open position.  I think I'm going to lube all of the joints there first.

Tom, you're my literal hero in dailying these beasts!  My household is downsizing fleet size, and as the only working member who's commute is both very short, and also served by reliable bus service, I've drawn Rambler duty.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/23/2022 at 10:21pm
Well thanks! Divide and conquer helps. IT's too easy to get distracted by a dozen (or only three) problems. If the throttle linkage is AFU, then disconnect it. You don't need it to get the curbside basics right.

YOu might find that when you get the carb untangled, the ignition might not be as perfect as you thought. It doesn't mean you're a bad person, lol. You'll both get better at it, notice more, and unmask subtler problems with incremental fixes.

And you'll discover why the EPA demanded 100,000 mile tuneups from new cars. This stuff can get really subtle; and paying by the hour, the tendency was to fix things "good enough" to get to work, etc. Today with a 50, 60 year old car, your focus is probably different. I spend the time to unsort this crap because 90% of the time I actually enjoy it, lol, and can spend the time thinking and working  in ways I could I couldn't 40 years ago.

You wanted adventure, you got it. Didn't? Too late now! lol 

My millennial neighbor recently bought a nicely done 32 Ford. He has no idea what a carburetor does, at all. He was driving with the choke on all the time. There's only two adjustments (Zenith 2) and both were of course fouled up because the choke was on. He's very smart -- but this is all alien tech, no one around him has any (^&*)&()*( idea what anything like this is -- but he's persisting and figuring it out. He's worked out the crashbox (no synchros) just fine. We all don't know something.

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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