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Mistery miss...Looks like a timing chain is in my future.
https://www.slantsix.org/forum/viewtopic.php?t=24807		 Page 2 of 2
Author:  Aggressive Ted [ Fri Sep 07, 2007 8:35 am ]
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Is it running bad out of gear? or just when you put it in gear?
Are you running the stock cam? or a new higher lift?
Author:  SlantSixDan [ Fri Sep 07, 2007 8:36 am ]
Post subject: 
Swapping engines to address a misfire is pretty drastic unless/until you've determined it's a problem with the engine itself.

You mention swapping a bunch of ignition components...what can you tell us about your carburetor(s)?
Author:  Eric W [ Fri Sep 07, 2007 10:18 am ]
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The carburetor is a rebuilt unit that I've had for several months now. I had to go through it when I bought it, and performed just fine. I went through it again (cleaned metering block and body passages, replaced gaskets) just to be sure it wasn't the problem.
Author:  Doc [ Fri Sep 07, 2007 11:47 am ]
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What is the timing when the at idle, vacuum advanced connected?
Sometimes the vac. advance will pull-in at idle and cause a miss-fire.
DD
Author:  Eric W [ Fri Sep 07, 2007 3:23 pm ]
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Its set to 8*BTDC. I disconnected the vacuum advance this morning with no change. Then drove to work doing 65 all the way with no issues. Thats why I'm stumped. Idles crappy, runs great! :?
Author:  SlantSixDan [ Fri Sep 07, 2007 3:50 pm ]
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I still think it's in the carburetor. Remember that 1920s after several decades' service can just plain reach the end of the road. If you have a spare metering block, you may want to try swapping it in. Otherwise, well, can I interest you in a really nice '72-compatible BBS? :-)
Author:  argentina-slantsixer [ Fri Sep 07, 2007 4:17 pm ]
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what did you do for cleaning up the carb? I mean, did you immerse the metering block in something, or used ultrasonic cleaners? maybe some crud got loose inside the metering block clogging the idle passages. Or maybe inside the carb's main body.
Author:  hotwheelsjr [ Fri Sep 07, 2007 9:23 pm ]
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Quote:
The carburetor is a rebuilt unit that I've had for several months now. I had to go through it when I bought it, and performed just fine. I went through it again (cleaned metering block and body passages, replaced gaskets) just to be sure it wasn't the problem.
Ditto -- same here. Similar problems with two different carbs -- both 1920's, though.

Ditto on driving, too -- runs great, except for the stumble from a dead stop...idles like crap. Big diff between his and mine are that I have my timing super advanced (about 3 inches ahead of the tab) to make it run decent. Also, I can't time it unless the vac advance is hooked up -- it dies if I pull the vac advance off and plug the vac line.

Also -- same symptoms, both motors, both carbs, and both distribuotrs. Very weird. I am going to look for a vac leak this weekend. I messed with it the other night and have it running the best it has, but it's still not right. Timing is way advanced and idle-mix screw is out about 3 turns -- plugs are a nice tan...maybe too tan and running lean? Vac leak would do that, huh? What baffles me is, with a vac leak, my timing should be fluxing...it's not -- it's rock steady -- just super advanced.

BTW -- swapping the motors was no big deal -- I got the second motor for next to nothing and it's a newer motor with a later head for unleaded fuel. Previous motor had already ate one head by sinking it's exhaust valves.
Author:  Eric W [ Fri Sep 07, 2007 11:47 pm ]
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Cleaned carb with carb cleaner and compressed air. Already tried tried a different metering block....no change. I've tried every trick I know to trace this f'in miss. Guess I shouldn't expect a great running engine thats 34 years old and gets driven 20K+ a year. Dan, PM me about the Carter please.
Author:  Eric W [ Sun Sep 09, 2007 9:19 pm ]
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Checked the timing chain tonite...yeah, its bad. Lots of play, which would explain the variance in timing at idle and when I rev the engine. So, looks like a timing chain is in order. I've never replaced a chain on a slant, only big blocks. Anything to watch for or any tricks?
Author:  DusterIdiot [ Mon Sep 10, 2007 7:02 am ]
Post subject:  In or out of the car?
Quote:
I've never replaced a chain on a slant, only big blocks. Anything to watch for or any tricks?

Doc has a good article on sealing the oil pan up, on the slant this can be a toughy in the car, if you are replacing the front oil pan/timing cover gasket, with a new set and the old oil pan gasket is still intact and squished... Otherwise everything can be done through the front of the car, and you'll need a damper puller, and a bolt (to put the damper back on the crank snout). Also now is a good time to check your cam and crank orientation, some of the timing sets don't line the dots up so well...

-D.Idiot
Author:  mszauner [ Mon Sep 10, 2007 6:09 pm ]
Post subject:  Sometimes they fight back
Careful on the timing gear cover gasket. I replaced timing gears on mine and as I was trying to stuff the gasket on the front of the pan, my hand slipped and I cut my finger on the knuckle to the bone. Bled like a stuck pig. It was New Years Day so I did not feel like sitting in the ER all day so I used super glue and steri-strips and it came out fine...that's what they do in ER's rather than suture anymore.

Someone, I think Dan, mentioned the carb. He was right about that on mine (1920). I had all kinds of weird things happening. I also used to regularly check the carb nuts to see if they are tight. I finally put lock washers on and that stopped that ritual.
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