Using the instructions at
The 258 BBD carb metering pins were set to full rich .
Did the purple / orange wiring splice to bypass emission box.
Changed from manifold vacuum to ported vacuum .
Jeep fired up somewhat AOK , idled very rough .
Timing has been troublesome.
No timing light in hand . Trying by ear until I can get a good timing light .
Prior timing appeared to be very far advanced already as the vacuum advance outlet tube was pushed up against the engine block .
It would have been impossible to turn distrib more counter clockwise . Could not advance any more.
By default , I turned distrib clockwise , as if to retard .
This is opposite to Nutter directions , I believe.
Engine idled at poor level , but it would idle.
I figured that adjusting timing would resolve all .
Result - rough idle , burping . Acceleration while parked seemed AOK yet...
when I release pedal , the engine backfires and stumbles and rocks and sounds as if it would explode. Dangerous looking , sounding.
After 30 seconds, idle smooths out a bit , but still not great.
I can not drive this out of the driveway .
I suspect that timing during deceleration is way off.
Any comments ?
I will have to do this by ear until a timing light is available.
Get a timing light. Unless you really know what you are doing, you can't time it by ear.
AFTER you get the base timing set right, you can experiment with adjusting the vacuum advance and/or switching it back to manifold vacuum.
Also, see these instructions which say it is better to put the needles in the middle. http://www.jeepforum.com/forum/f8/ho...bypass-522262/
You can try using a vacuum gauge to set the timing instead (search for how), but you should just buck up and get a timing light.
I agree that timing light is best. I had an old 1972 style w/o induction and did not have the proper adaptors.
Can you comment on the rotation of the distributor?
It was my understanding that counter clockwise turning will advance the timing .
It is maxed out at counterclockwise rotation and the vac adv hits the engine block with the OEM setup.
After doing Nutter and having issues , I reverted to OEM wiring /vac adv .
The BBD carb metering pins will respond to adjusting the air/fuel mix screws.
it is 90 plus degrees and I am considering waiting for cooler temps if I can make it .
Thank you for your input .
You will find manifold vacuum gives better drivability and gas mileage.
If you can't get enough adjustment on your dizzy, you may have to re-install one tooth over.
Most folks have better luck setting the metering pins at the mid point instead of full rich.
A timing light, a vacuum gauge and a multi-meter are absolutely must haves for YJ owners.
No vacuum advance
Try running it with no vacuum advance. Disconnect the vacuum hose to the distributor and plug it. See how it runs.
I am having a similar problem with my own jeep and the only way it will run is with the vacuum disconnected. I can get it started and set the timing with the vacuum disconnected, but as soon as I connect it and try to get it above idle I get the backfiring (both through carb and through exhaust).
Just take a paperclip and bend it so it fits down in the distributor cap where the #1 wire attaches. Have it hang out when the wire is back on. Just hook your pickup lead to the end of the paperclip. Works great. My Sun timing light was made in the mid 60s, still using it today.
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