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Carb issues

1K views 10 replies 5 participants last post by  ChevyBoy2010 
#1 ·
Im struggling with this darn carb. Its an Edelbrock 1406 with a Performer EPS manifold and a mild cam on a SBC in a 6000 pound rig with TH350. I rejetted it to what the local engine builder says is optimal for this altitude (5200 ft) and it ran GREAT in the summer. Now that theres a foot of snow on the ground, it hates life miserably.

I have to pump the pedal about a hundred times and crank for a good 30 seconds to get the thing to start. My choke is not coming on (easy fix, just havent had time to do it yet) so I have to feather the throttle for a good 2-3 minutes to keep it running. On start up it idles at about 400 rpm, but once it is up to operating temp, it idles at around 900-too high! The truck refuses to run right until my water temp reaches about 165 degrees, I have a 190 thermostat.

You have to nearly idle while driving until it reaches temp, otherwise it chokes itself out and dies. Once I reach temperature, it runs great! BUT it studders when applying throttle at any cruising speed. I think I'm running a little fat.

I was wondering what jets and metering rods you all recommend? I cannot recall what I put in it.
 
#2 ·
. My choke is not coming on (easy fix, just havent had time to do it yet).
This is your problem. All of your problem.

If it's not, fix it FIRST and then try to diag any potential other issues. Carbs are SIMPLE, so it is likely not a complex issue if it was just running great
 
#3 ·
The choke was too rich and not kicking off and presenting the same problem I have now. I backed it off too far and the problem is still there. But I will give it a shot. I dont see how the choke not engaging has anything to do with it bogging down under throttle at operating temperature.
 
#4 ·
Well, maybe I read your post wrong, but it sounded like you were having starting/drivability problems while cold, and that once warmed up, it was simply idleing high.

The high idle could be cause by a bunch of different things, but a choke not funtioning properly is one of the potential problems.

All of your cold issues sound choke related. It is always easier to fix the known/free issues first before trying to diag the mystery shit also.
 
#5 ·
Im struggling with this darn carb. Its an Edelbrock 1406 with a Performer EPS manifold and a mild cam on a SBC in a 6000 pound rig with TH350. I rejetted it to what the local engine builder says is optimal for this altitude (5200 ft) and it ran GREAT in the summer. Now that theres a foot of snow on the ground, it hates life miserably.

I have to pump the pedal about a hundred times and crank for a good 30 seconds to get the thing to start. My choke is not coming on (easy fix, just havent had time to do it yet) so I have to feather the throttle for a good 2-3 minutes to keep it running. On start up it idles at about 400 rpm, but once it is up to operating temp, it idles at around 900-too high! The truck refuses to run right until my water temp reaches about 165 degrees, I have a 190 thermostat.

You have to nearly idle while driving until it reaches temp, otherwise it chokes itself out and dies. Once I reach temperature, it runs great! BUT it studders when applying throttle at any cruising speed. I think I'm running a little fat.
I was wondering what jets and metering rods you all recommend? I cannot recall what I put in it.
Well, maybe I read your post wrong, but it sounded like you were having starting/drivability problems while cold, and that once warmed up, it was simply idleing high.

The high idle could be cause by a bunch of different things, but a choke not funtioning properly is one of the potential problems.

All of your cold issues sound choke related. It is always easier to fix the known/free issues first before trying to diag the mystery shit also.
I set the idle high enough to idle when cold without having to feather the throttle too much. I do believe this could likely be because the choke is not properly adjusted. My main concern is how terrible it runs until the 165 degree range. Once at 190, it runs fine other than the bogging when throttle is applied. I also got 3 mpg better during the summer months than I do now.
 
#6 · (Edited)
from what your describing here i have a possible answer. for one, are you running a stock air cleaner with a heat riser tube from your exhaust or is it an open element air cleaner? warm intake air is important in cold climates for drivability, simply put it's hard to light a good fire in cold air. second, when you installed the manifold did you install the correct exhaust crossover restrictors in the intake gasket, or did you block them off alltogether? if the floor of the intake under the carb is too cold the fuel will puddle and make for all kinds of drivability problems that are very similiar to the ones you stated you had during warm up.
 
#8 ·
IIRC I did not install the block off plate, they are free flow. I do not have the exhaust crossover, its is an open element. I have a riser from the intake to the carb to keep the heat off of it. The problem is the truck will act like this (though not so severe) when the temperature drops below 60 degrees. IMO that should NOT be cold enough to cause the problems im experiencing.
 
#7 ·
i dont ahve the choke hooked up on my edelbrock. i have to pump for 15-20 or so times in the morning when it is cold. give it a little gas then it fires up and idles fine.

I had issues with my truck running too rich with the choke on so thats why i have mine disconnected.

I had a problem with one of my needles not seating all the way. Cleaned carb like hell and it was still having issues. I got the offroad needles and seats and that seemed to fix the issue. It would do like you are saying. Run pretty good when warm but then when i got on the throttle it would bog. i would take the top off the carb and do some poking around.
 
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