AMC Eagle Den Forum

The Mighty 258 => Fuel Systems. => Topic started by: ammachine390 on June 07, 2012, 08:30:55 PM

Title: Carb rebuild success (with videos)
Post by: ammachine390 on June 07, 2012, 08:30:55 PM
I've been thinking about rebuilding the carb for a while now, and I'm finally getting around to it. Does anybody have any good suggestions on what brand to kit, or where to purchase a kit? Is there a kit that has everything included, including a new float? I'm new to this, as I've never rebuilt a carb before, but am willing to try it. I still have the feedback carter carb, and even though it always starts instantly, I think it could run a little better, and hopefully get more mpg. Thanks.
Title: Re: Where to find a good carb rebuild kit?
Post by: TLC87Eagle on June 07, 2012, 11:32:57 PM
Rock Auto has kits pretty cheap. I rebuilt mine last month. They don't come with floats, but I believe Rock Auto also sells those separately, though I don't know why you would need to change the float unless it was bad. 
Title: Re: Where to find a good carb rebuild kit?
Post by: DaemonForce on June 07, 2012, 11:33:12 PM
I'm not getting the float but a few months ago I bought a Walker kit from O'Reilly's and tomorrow morning I'll finally get to use it. I'm rebuilding one of the downdraft CJ-5 carbs and plan on eliminating the stepper motor garbage. I know that means I have a lot of other work to do but I don't care. Anyway it was $11 then. Not sure if it went up since then but these things must be ordered often since I managed to snag the last one in town.
Title: Re: Where to find a good carb rebuild kit?
Post by: shaggimo on June 08, 2012, 08:38:25 AM
I have had great luck with Napa/echlin kits, reasonably priced, but do not come with floats, usually with any kit, you have to order the float separately.
Title: Re: Where to find a good carb rebuild kit?
Post by: carnuck on June 08, 2012, 12:39:26 PM
I avoid the black foam floats if at all possible. Modern gas eats into them and then sinks them.
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on June 08, 2012, 10:18:53 PM
Thanks everyone for the tips.

I was under the impression that if a carb is torn apart to be rebuilt, the float should be replaced. Is this not true?

Also, is there anything else that should be replaced, that's not part of the rebuild kit?

Thanks again.
Title: Re: Where to find a good carb rebuild kit?
Post by: shaggimo on June 11, 2012, 08:04:14 AM
Depends, if you find a brass float inside, and it's in good condition, meaning no pin holes, there's no reason to replace it (submerse it in fuel, if it doesn't take on any, you're good to go). If you find a plastic or nitrophyl float, it can be tricky to see whether or not it's good, best to replace it just for good measures. Usually, nothing else is needed other than what's in the kit, I'd assume you'd put a new fuel filter on while you're there (kinda goes without mentioning, lol).
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on June 11, 2012, 05:27:37 PM
Thanks for the tips shaggimo.
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on July 13, 2012, 12:25:17 PM
I finally started taking the carb apart yesterday. But I'm having a problem with the fast idle cam retaining screw. The screw is in so tight and will not budge, I've been soaking it with penetrating oil, but it's still in there. I didn't want to force it too hard as I don't want to strip the screw, or break anything. The same thing is happening on my spare carb. Also, I found a youtube video of a BBD being torn down, and that guy struggled with this screw as well. Anybody else have this issue? Any good tricks to get it out without ruining it.
(http://i815.photobucket.com/albums/zz79/ammachine390/IMG_0638.png)
Title: Re: Where to find a good carb rebuild kit?
Post by: shaggimo on July 13, 2012, 01:16:13 PM
Big, sharp (or new) screwdriver will limit the potential for damage (no joke), I have specific screw drivers I use for my carb rebuilds, it does make a difference. It may have lock tite on it too, it's been a while since I've done a bbd, but I think I remember fighting with mine a bit too.
Title: Re: Where to find a good carb rebuild kit?
Post by: midtownboarder on July 13, 2012, 01:39:41 PM
definitely try to find a screwdriver with the widest head possible, that's what i used and didn't have hardly any trouble...
Title: Re: Where to find a good carb rebuild kit?
Post by: carnuck on July 13, 2012, 02:15:31 PM
Why take it off? You can clean/lube behind it and take the linkage off without removing it.
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on July 13, 2012, 02:20:17 PM
I got it off. I remounted it to the intake manifold, and then used a pair of channel locks to break the screw loose. Then used my big screwdriver to get it out. Thanks for all the tips. Now I am waiting for the screws that attach the choke to the throttle body to soak, hopefully they come out with ease.

Why take it off? You can clean/lube behind it and take the linkage off without removing it.
Good point, that's was what I thought I was going to have to do. Just following the service manual's instructions for disassembly.
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on July 14, 2012, 01:12:19 AM
Alright, I got the carb completely torn down. Gonna start soaking it in the cleaner tomorrow. Before I took out the mixture screws, counted the turns it took to seat them fully. The left one was 5 turns, and the right took just a little of 3 and half turns. Obviously, these cannot be correct, as they should be the same number of turns for each mixture screw. But doesn't it also seem VERY rich. I thought I read somewhere that idle mixture should start out at 2 and half turns out from seated, then fine tuned from there. Is that right? Where's a good starting point? The service manual says to use an expanded scale tach and to adjust the mixture watching the idle rpm drop. Is using a vacuum gauge to get the highest reading just as accurate as the lean best idle method? I'm still using the feedback system, if it matters.
Title: Re: Where to find a good carb rebuild kit?
Post by: carnuck on July 15, 2012, 01:13:14 PM
One side was probably clogged up. I usually start at 3 turns each, then back out or turn one in till it sounds right (highest RPM) and count the turns. Split the difference between the two (usually within 1/2 a turn)
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on July 17, 2012, 10:19:41 PM
Working on putting it back together. I got the float level set, but when the baffle is put in, the float tab hits it and the float cannot drop all the way to the bottom. It will go up as far as it should, but not down. Is this supposed to happen? I wasn't sure. I bent the tap, so that the baffle doesn't interfere, and now the float can rest on the bottom of the bowl. Is this right?

(http://i815.photobucket.com/albums/zz79/ammachine390/IMG_0658-1.jpg)
Here's the tab.

(http://i815.photobucket.com/albums/zz79/ammachine390/IMG_0659.jpg)
And here's how it's bent to allow the float to be able to travel from the base to the set height. That right? Or should the float not be able to drop to the bottom?
Title: Re: Where to find a good carb rebuild kit?
Post by: carnuck on July 18, 2012, 12:39:01 PM
Dropping to the bottom when empty is fine. I hold the bent spring over the float pin (and make sure the ball bearing in the accel pump isn't loose) and turn the carb upside down to check the float level.
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on July 18, 2012, 01:16:01 PM
Thanks Carnuck. I figured it should go all the way to the bottom when empty, but I've never done a carb rebuild before and wanted to make sure. Really don't wanna have to tear it apart after getting all back together. And that sounds like a good way to check the float level.
Title: Re: Where to find a good carb rebuild kit?
Post by: ammachine390 on July 22, 2012, 07:46:07 PM
Got it all back together, and back on the car on Friday. Got it all tuned yesterday and today, and its running great again. Just filled up my gas tank so I can track the mpg, hopefully it goes up a bit. I think it will because before the rebuild, the gaskets on the carb always looked a bit wet with gas, now they're sealed up good.

So thanks to everyone for all the tips and all the information. Eggs to everyone.
Title: Carb rebuild success (with video)
Post by: ammachine390 on July 26, 2012, 02:29:46 PM
Figured I'd put up a video of the car starting with the carb rebuilt.

Cold start (even though the ambient air temp was around 90 degrees):
http://www.youtube.com/watch?v=WeUU_45f2YY

Hot start:
http://www.youtube.com/watch?v=IF03LVx0kEM

Idles pretty good. Starts up quick. And that's with all the original emission stuff still attached and functioning. Just shows ya that a BBD can start and idle good.