Arrgh!!!

I've recently rebuilt my carb. and finally got it working pretty good. One of the reasons that I decided to rebuild it in the first place was I had a vacuum leak near the base of the carb. so I thought if I'm in there with gaskets I should just do the whole thing. It was fun and a good experience.

The carb is running very rich and the only way I can keep it idleling is to back out the mixtures screws pretty far. I also still feel that I've got a vacuum leak, it still sounds like it is around the carb, but I have sprayed carb cleaner all around the area and also all around the intake manifold, but I do not get any change in engine rpm. Maybe these Rochester carbs are just loud. I've got 17+or- inches of vacuum, timing set 5 degrees btdc, dwell at 30.

Question is this: Why so rich and idle still rough. The jeep runs well otherwise. Should I try and change manifold gasket? Any ideas on how to track down this vacuum leak?

 

the carb is running rich because something is wrong inside
the vac leak doesn't create the rich carb condition
I would double check the float setting and make sure the needle and seat are working properly.
with engine idling, do you see fuel dripping off the venturis ? if so, this indicates a float/needle problem. The float pivot pin might also have fallen out of the hole for the float.
take the top off the carb off; how high is the fuel level ?
fwiw...your vac reading appears okay to me at 17"

 

Seems that this is a recurring problem/question. I recall it's sometimes caused by leftover carb. cleaner messin' up the seals, e.g. float needle in this case. Solution - Make sure the carb. is completely clean including passages before reassembling. Just a thought.

 

I didnt notice any gas dripping from the venturis, but I'll double check that tonight. Last night I took the top off the carb and double checked the measurments and the needle, all check out ok. The bowl was slightly more than half full when I removed the top.

 

I took a look at the venturi last night while the jeep was runnng and I didnt notice any fuel dripping.

How much fuel should be in the bowl? I have to back the idle/mixture screws out around 4 turns just to keep this thing running.

 

Should run at two turns out. then fine tune from there.

Could be you need to take it apart again and blow all the passages out with compressed air. Could be old gasket material or varnish from old gas. And what is your fuel pressure from the pump? Stock mechanical or electrical aftermarket? Did you resize the jets? or maybe reset the needle wrong?

Could also be I'm talking through my hat, seeing as how I AM NOT the worlds greatest mechanic.R):hurrican:

 

Thanks for the reply. I thought it should run at 2 turns out, but unless I go 3 turns +, it stalls out. I'm planning on starting over today, reclean and rebuild. I'm also going order a new float today.

Do you think a vacuum leak somewhere could be part of this problem? I have a mechanical pump and as far as I know the original jets but I could be wrong.

 

Just finished moving in to the new house and still haven't figured out which one of the 125 boxes in the garage has my Jeep books in it. Found a copy of Petersen's Big Book of Auto Repair though. (1970 to 1980 vehicles)
Mixture screws base setting is two full turns from being lightly bottomed out.
It states that turning the screws in will lean the mixture, and out will richen the mixture. 4 turns is really on the rich side of things. I'll keep looking for my Jeep books.:hurrican:

 

Thanks, congratulations on the new house. It really smooths out nice around 3 to 4 turns out. Any ideas what could cause this conditon? I've been through the carb twice, but I quess i'll have to go back in for more. I'm tempted to order a rebuilt unit.

 

Did you reset the choke, along with every thing else? Manual or automatic choke?

 

I have a manual choke, and it does seem to run better when I pull the choke out.

 

I may have missed it, by why do you think its running rich? You say that the idle needles have to be out at least 4 turns to make it run. To me, that means that the regular jets are not adding enough fuel and the idle jets have to try and make up for it. Are you sure that its running rich and not lean? I am no carb. expert by any means, but I did not catch why you thought it was running rich.
Luck

 

vacuum leak. Turning the idle screws 4 turns out is giving more fuel so that it will stay running due to increase in air because of a vacuum leak.

 

unless the exhaust makes your eyes water real bad, it's not running rich. older cars (before catalitc [sp?] converters) smell like their running rich compared to newer cars.

 

Oh, heck!

Just drill a hole in the tailpipe about 2" in and thread a spark plug into it.
hook up a switch with one lead to positive and the other to a buzzer, and then on to the spark plug. With a rich condition, you should be able to melt the front bumper off of any one tailgating you!:twisted:

(figured a little humor couldn't hurt)R)

has the air cleaner element been changed? A clogged one would cause a rich condition.:hurrican:

 

It sure smells bad and makes my eyes burn! I quess i'll take it apart again.

 

I like the spark plug idea best. I did change the air filter and even tried running it without one. It must be something inside that is clogged.

 

How old is your carb?
The shafts and bearing surfaces for them could be worn enough to cause your vacuum leak.

 

I wish i knew. The jeep is a 1971, based on the stamping numbers on the engine its from 1970, and I noticed the carb number stamped on the carb matched up with one for the late 60's (per the rebuild kit instructions)

I'm tempted to order a new rebuilt one. I've read several threads here and it sounds like several people have not been happy with the rebuilt ones. Do you or anyone else have advice on where to find a quality unit?

I'm planning on going through this unit one last time to make sure, but I suspect that it might have a vacuum leak in the bearing surface.

 

I'm still running the original 134 Fhead. I'm going to Solex when I need to replace or rebuild.

For the V6, I think I might go to a Holley two-barrel ( the one that looks like half of a 4150.)
Summit Racing? Pep Boys? CarQuest? Any local FLAP should have them. However, they ain't cheap, either. Or maybe CraigsList.org?