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Unread 12-13-2011, 08:29 AM   #16
Old4X
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1990 CJ7 
 
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On the 4.2 you can't have ANY vacuum leaks ! It will destroy the drivability of the engine.

When I start having any kind of idle problem on a carbed engine, the first thing I reach for is a can of spray cleaner and look for leaks. Fixes the problem more times than not when the vac leak is found and fixed.


And your engine isn't likely to be "stone cold" for 8 or more hours, overnight is what I usually plan on.

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Unread 12-13-2011, 08:40 AM   #17
JeepJon15
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Well its about 30 degrees here (maybe 40 in the garage) and i only had it running for 15 minutes or so to get to operating temp, i guess it was hopeful thinking it would only take a couple hours to cool enough.

I guess i will finish this up after work. Is it worth doing these things with a small vacuum leak? Or is that throwing the carb off so much that these adjustments will be irrelevant once the leak is fixed? Is there anything i can use to patch the leak on the carb temporarily so i can do these tweaks? If i do go ahead and finish this process and the jeep will run okay, should i still hold of on driving it until the leak is fixed, or can it be driven while i'm waiting for the rebuild kit to get here?

Order a rebuild kit? (I dont have the extra cash to upgrade the carb right now) Seeing as how some of the bolts on the exhaust manifold were loose (i tightened them) i may go ahead and order a new gasket too. Is that replaceable by a novice?

So many questions i know, and apologize.

Thanks a lot!
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Unread 12-13-2011, 08:45 AM   #18
oldtime_ironman
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Quote:
Originally Posted by JeepJon15 View Post
Well its about 30 degrees here (maybe 40 in the garage) and i only had it running for 15 minutes or so to get to operating temp, i guess it was hopeful thinking it would only take a couple hours to cool enough.

I guess i will finish this up after work. Is it worth doing these things with a small vacuum leak? Or is that throwing the carb off so much that these adjustments will be irrelevant once the leak is fixed? Is there anything i can use to patch the leak on the carb temporarily so i can do these tweaks? If i do go ahead and finish this process and the jeep will run okay, should i still hold of on driving it until the leak is fixed, or can it be driven while i'm waiting for the rebuild kit to get here?

Order a rebuild kit? (I dont have the extra cash to upgrade the carb right now) Seeing as how some of the bolts on the exhaust manifold were loose (i tightened them) i may go ahead and order a new gasket too. Is that replaceable by a novice?

So many questions i know, and apologize.

Thanks a lot!
Rule One with carbs is *always* fix the vacuum leaks *first* otherwise you'll never get it dialed in.
.
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Unread 12-13-2011, 08:56 AM   #19
Old4X
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Check that the hold down nuts are tight on ther carb. If that isn't the problem, pull it off and put a new base gasket on it.

An inexpensive vac gauge should be all you need. I bought the cheapest one Sears sold 43 years ago, still have it today, and works fine.
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Unread 12-13-2011, 09:15 AM   #20
JeepJon15
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Thanks, most of the nuts i was able to turn at least a quarter turn without much torque, that did seem to help some but i cant be positive there are no leaks without a gauge, yes?
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Unread 12-13-2011, 01:06 PM   #21
Old4X
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Quote:
Originally Posted by JeepJon15 View Post
Thanks, most of the nuts i was able to turn at least a quarter turn without much torque, that did seem to help some but i cant be positive there are no leaks without a gauge, yes?

No, you use a flammable spray cleaner like carb cleaner or brake cleaner to check for leaks.

While engine is running, spray down suspect area, if idle changes, there is your leak.

It goes without saying, you will be spraying very flammable liquid on hot engine parts with potential sparks nearby. BE CAREFUL!


Old saying: Build a man a fire, he will be warm that night. Set a man on fire, he will be warm for the rest of his life.......
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Unread 12-13-2011, 01:31 PM   #22
dtn8tr
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Quote:
Originally Posted by oldtime_ironman View Post
Completely offtopic, but I just wanted to say that it made my day to find somebody else who knows about carbs and timing. I was starting to think that I was the last one on earth... (I used to do GMC 4-barrels for performance)
.
LOL...I prefer my Weber to FI. Before I bought my YJ last year, the last time adjusted a carb was on my '71 Firebird 20+ years ago!
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Unread 12-13-2011, 06:28 PM   #23
JeepJon15
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Thanks for the clarification old4x. My thinking was even though i cant find a leak with the carb cleaner doesnt mean there isnt one. Which is why i mentioned the gauge. Seems i have at least one gasket on the carb leaking, and i think the exhaust manifold gasket may be leaky too... It will be sad to let this thread die, since i'm getting such great advice but i cant do anything else until i get some new gaskets at least.

I was thinking about buying a used motorcraft carb on ebay. What are your thoughts on this? Is it a bad idea to buy used?

At the very least i can bookmark this thread and refer back to your instructions once i have solid vacuum.

p.s. i thought your fire saying would end along the lines of teach and man to build a fire blah blah blah. Yours was much better haha.
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Unread 12-13-2011, 07:03 PM   #24
Old4X
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I personally prefer an OEM style carb on my engines. Several cars I owned in the past had that motorcraft carb on them, and they were serviceable, but had their own quirks. If you want to go that way, haunt some junkyards and swap meets. If you can get them cheap enough, get two and keep a spare all the time (I have 3 Carter BBDs all setup and ready to go).

A carb kit for your Carter is cheap, and has base gaskets included. You might pick one up to clear your vac leak, and do the overhaul at a later date.

That quote may not be correct, but I wanted to impart a visual message about the dangers we tend to get too casual about.
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Unread 12-13-2011, 07:16 PM   #25
JeepJon15
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You know what, i think i like my stock carb too. Even with these vacuum leaks shes still trying hah. The PO must have replaced the original because this one says re manufactured carbs on it or something like that.

I'll get a rebuild kit... Is it okay to just replace the leaky gasket or should i go ahead and rebuild it while i have it off? Please note, that while i enjoy working under the hood, i've never rebuilt a carb or even taken one off. I'm excited to get this vacuum leak fixed.
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Unread 12-13-2011, 07:24 PM   #26
Old4X
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While you have it off, clean out the idle tubes. It is easy and instructions are on the net under "Carter BBD Idle Fix".

You can check the float level at the same time as you will have the top off anyway.

Put the base gasket on and see how it runs.

Before you jump into rebuilding the carb, you might want to do some reading up on it before you have tiny bits running around on top of your work table.

Between articles on the Net, and having the carb kit (and instructions) in your hand, you will get a good idea of what to do and how to do it without being rushed for time.

This carb is only slightly more complicated than a lawnmower engine, not difficult to service at all.
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Unread 12-13-2011, 08:05 PM   #27
JeepJon15
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AH so after i do this ill finally be able to fix that damn lawnmower!

Ill start with the base and main gasket before i try rebuilding. It was hard to tell if the main seal (the one in the middle) was leaking vacuum, or if it was all the base, but i figure its worth doing both.

Thanks a lot!

Oh and i have done the idle tube cleaning once before. It was around june or july and the jeep is always stop and go traffic so it is probably due again. Finally something i'm comfortable doing without 2 hours of research hah.
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Unread 12-14-2011, 05:29 PM   #28
JeepJon15
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Hey Old4x, or anyone who may have the answer. When removing the carb it says to remove the throttle cable and TV cable (auto trans). I cant figure out how to get that bar off that goes from the linkage on the fender side of the carb down to what i believe is the TV link. I have a Haynes manual, and its helpful, but i'm a bit confused. There is a philips head screw at the top of the little pencil thick bar i'm talking about, but the head grooves are so shallow i cant fit a screw driver head in it. I tried scraping the screw head, and it did free up some rust and stuff, but its still far too shallow.

Am i doing something wrong here? I was able to get the very bottom gasket removed, and a new one on by just moving the carb, but id like to replace the other couple gaskets.

Thanks in advance,
Jon
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Unread 12-14-2011, 06:44 PM   #29
Old4X
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Isn't it just a spring type fitting on a ball stud? If so, it just pops off (I pry with a screwdriver close to the stud).

The screw looking thing on the fitting is to take up slack in the fitting if I am thinking about the right part.
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Unread 12-14-2011, 06:53 PM   #30
JeepJon15
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I'm not sure i follow exactly. What i'm getting out of it though is that i should use a screwdriver on the top of the bar where it connects to the throttle body to pry it apart. I'll go out and see if i can figure it out once i see it again, had to take a break for dinner. Thanks a lot! Ill let you know how it goes.
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