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post #1 of (permalink) Old 01-16-2013, 12:04 PM Thread Starter
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cj7 slow to go

Hey guys need a little tech advice. 79 cj7 with the 304 and 2bbl ford. automatic with quadratrac. For the last month or 2 Its been running like a dream, did a tune up, set the timing, rebuilt the carb, about 6-8 months ago, no issues. Even when the temps dropped down to the single digits, still started up good, which was kind of surprising. I got off work saturday morning around 7, ran great. did not drive it again until sunday at about 9:30Started a little rough, but it was around 18 degrees here. I let it warm up and when I hit the road, I couldn't get above 20 miles an hour forever. It runs great at idle, and at high idle, but under load, it will not get up to speed as quickly as it should. Choke appears to be working properly. It bogs down considerably. Once I get rolling it eventually will take off and run somewhat normal,I can hit 65-70 on the highway, but every time i leave from a standstill it acts like I've got a 100,000lb trailer on the back. All my ign. components are newer, I've got new carb insulator gasket to put on, but carb does not appear to be sucking air. Vacuum lines have been double checked. new fuel pump and filter last month. Transmission seems to be shifting ok, runs through all the gears ok. possible compression issue? Kind of at a loss. Any ideas would be appreciated.
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post #2 of (permalink) Old 01-17-2013, 09:47 AM
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My first impression is that timing is off. It could be that the mechanical advance is stuck. Put the timing light on it, disconnect and plug the vacuum advance, and see if it's where it should be at idle and advances with engine speed.

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post #3 of (permalink) Old 01-26-2013, 05:10 PM Thread Starter
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thanks Jim. Double checked my timing, and my vacuum advance for proper operation and all is well. Did however find on closer inspection that there was a crack in my carb, down near wear it bolts down. Ordered a new carb, waited a week, finally got it in. Swapped it out, and will not run. They sent me a 1.21 bore size. My original size was 1.08. Now i can't get enough fuel due to all the air. Any suggestions on a new jet size. Don't really have the time to wait on sending the carb back and waiting and hoping I get the correct one the next time around. Can I make this work. I've heard it has been done and worked well, what do I need?
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post #4 of (permalink) Old 01-26-2013, 08:28 PM
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odd that it will idle with a cracked carb but suffers under load. PCV valve? EGR system? Have you checked the function of any mechanical or vacuum advance? not sure what else to suggest.
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post #5 of (permalink) Old 01-28-2013, 04:25 AM
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I would get the right size first off. While I was waiting for that I would smear a little sealant on the old one where it is cracked and go back to tinkering, but that is me. Heck, I would have tried the sealant first,, I am tight.

Ya only go around once, best to enjoy it the first trip.
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post #6 of (permalink) Old 01-29-2013, 09:57 AM
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What the others said. Don't try to make the wrong one run. Besides being an unpredictable course, and one which you shouldn't have to follow, it will throw a monkey wrench into solving your original problem. As long as problems persist you'll be unable to tell whether they're caused by the wrong carb or some other problem. You'll be chasing your tail in circles. When troubleshooting a problem never make more than one change at a time - it you do there's no way to tell which change is having which effect.

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