Issues

[83kid]

Hi,
So i have a 5.7 350, seeming to be out of a '90 truck:
edelbrock 1406 carb, on a holley street dominator intake (probably swapped the intake so as to not have to add all the EFI crap into this truck)

Used to run fine for a good while.
Then one day like 6 months ago it dieseled, and continued to do so each time i shut it off

Just shut it off in gear for a while, then i adjusted the idle screw so it wouldnt diesel - idled too low in gear then.

Adjusted the mixture screws, and idle screw, and after changing them around a good 5 or 6 times i cant get it to stay going good
Ill adjust it (according to online directions of edelbrock for this carb), and itll all be set. I live in new england, so i set it hot in the afternoon, then like the next day say in the morning when its a little cooler i go to accelerate shortly after starting and it doesnt want to, you can give it a little throttle and its a few seconds delay before the engine reacts - it kind of bogs when you first give it gas. Once truck is warm, no problem. Later in the day, this issue mostly goes away, but most of the day its still a little there, when its hotter out, but only immediatly after starting truck and driving.
Cant get the idle speed right even with adjusting the screws, if it runs good in gear and driving around, itll diesel.
Idles low enough to not diesel i have to give it a little gas to keep it from dieing out in gear.

Possible vacuum leak... has a little bit of that noise when standing with the hood open, but i wouldnt exactly rely on that as the problem

Any ideas?

 

[crazy4offroad]

Vac leak is a real problem, a vac gauge will tell you if it really exists or is just the venturis making noise. These carbs are very sensitive to dirty fuel. If you use one of those nifty cleanable screen type filters they let a lot of garbage by. Mine was running bad and I took the top off the carb and cleaned out the port and passage the fuel line connects to and it was a real bitch lol. A piece of coat hanger or something like that helps. What I found packed in there was like black sand, which turned out to be disintegrated black rubber fuel line bits that had got past my filter. Today's gas with ethanol added wreaks havoc on rubber fuel lines, and subsequently carbs. After getting it cleaned out it was much better. You may also want to blow out the idle air circuits using compressed air. You will have to dab all the gas out of the float bowls with a rag, be sure to have safety glasses on, put a short piece of vac hose onto your air nozzle and hold the end of the hose tight to the primary (front) jets. The ones the metering rods slide into. It doesn't take much to blow them out, just a few blasts. When reassembling be sure to pick up a couple regular AC Delco fuel filters. They are translucent plastic, not exactly transparent, and have a paper filter in them. And they're cheap! Throw one in the glove box or wherever you might keep an extra ignition module in case of problems when you're out and about. Then down the road you may want to think about swapping out any rubber lines with ethanol-proof fuel lines to prevent permeation. The ethanol additive is exactly the same as pure moonshine, and I've seen that stuff strip the finish off a wood table, polyurethane, stain and all, from just a simple spill. Some people specifically buy their gas from certain stations to avoid ethanol in older vehicles. I think BP and Exxon stations have ethanol-free gas but you may want to google that.

 

[crazy4offroad]

One other thing, if it seems to run badly and hotter than normal which can cause dieseling, the idle air circuit is most likely clogged. When clogged, the vacuum of the engine draws fuel out of the venturis instead of the idle air circuit making it impossible to tune out and making it run extremely lean and hot. If I had to guess, that is going to be your problem. Once you get everything cleaned and filtered properly you'll have to re-tune everything. Idle, idle-air, and timing, then re-check them all as adjusting one usually affects the others.

 

[rich weyand]

Couple questions:

Did you change anything else that may be a cause?

Have you ever cleaned the step-up pistons and cylinders? They get dirty, and then stick, and then give a hesitation on acceleration. You loosen the two screws on the top of the carb under the air cleaner, swing the little caovers to the side. They'll pop up and you can pull them out. Wipe them off with a rag, and wipe out the cylinders with a qtip and put them back in. Make sure they bounce up and down freely.

 

[83kid]

Couple questions:

Did you change anything else that may be a cause?

Have you ever cleaned the step-up pistons and cylinders? They get dirty, and then stick, and then give a hesitation on acceleration. You loosen the two screws on the top of the carb under the air cleaner, swing the little caovers to the side. They'll pop up and you can pull them out. Wipe them off with a rag, and wipe out the cylinders with a qtip and put them back in. Make sure they bounce up and down freely.

Vac leak is a real problem, a vac gauge will tell you if it really exists or is just the venturis making noise. These carbs are very sensitive to dirty fuel. If you use one of those nifty cleanable screen type filters they let a lot of garbage by. Mine was running bad and I took the top off the carb and cleaned out the port and passage the fuel line connects to and it was a real bitch lol. A piece of coat hanger or something like that helps. What I found packed in there was like black sand, which turned out to be disintegrated black rubber fuel line bits that had got past my filter. Today's gas with ethanol added wreaks havoc on rubber fuel lines, and subsequently carbs. After getting it cleaned out it was much better. You may also want to blow out the idle air circuits using compressed air. You will have to dab all the gas out of the float bowls with a rag, be sure to have safety glasses on, put a short piece of vac hose onto your air nozzle and hold the end of the hose tight to the primary (front) jets. The ones the metering rods slide into. It doesn't take much to blow them out, just a few blasts. When reassembling be sure to pick up a couple regular AC Delco fuel filters. They are translucent plastic, not exactly transparent, and have a paper filter in them. And they're cheap! Throw one in the glove box or wherever you might keep an extra ignition module in case of problems when you're out and about. Then down the road you may want to think about swapping out any rubber lines with ethanol-proof fuel lines to prevent permeation. The ethanol additive is exactly the same as pure moonshine, and I've seen that stuff strip the finish off a wood table, polyurethane, stain and all, from just a simple spill. Some people specifically buy their gas from certain stations to avoid ethanol in older vehicles. I think BP and Exxon stations have ethanol-free gas but you may want to google that.

One other thing, if it seems to run badly and hotter than normal which can cause dieseling, the idle air circuit is most likely clogged. When clogged, the vacuum of the engine draws fuel out of the venturis instead of the idle air circuit making it impossible to tune out and making it run extremely lean and hot. If I had to guess, that is going to be your problem. Once you get everything cleaned and filtered properly you'll have to re-tune everything. Idle, idle-air, and timing, then re-check them all as adjusting one usually affects the others.

So, from this ive decided to just rebuild the carb to make sure its completely clean. Not sure what i have for a filter, or where, so ill be replacing that and if you have any suggestions, id like to throw something thatd have no problem with most fuels for a filter, and i might as replace the rubber fuel line to make sure its all good...
Any suggestions of the filter?

 

[rich weyand]

The Eddy 1406 does not have an internal fuel filter. So you should be able to see a fuel filter in the line from the fuel pump to the carb, usually at the carb end.

Do not use a glass filter. I use a metal filter on mine, which you can see in this photo just behind the heater hoses.

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[MadOgre]

I use a metal screened filter that is a 2 piece so you can replace the metal screen. The screen is not like fly screen it is little pellets melted together. This filter works amazing!. Just popped the lid off my carb the other day to replace jets and rods and the fuel and fuel bowls were spotless!

Just popped the lid off my buddies 1406 the other day to change jets and rods and his fuel bowls were full of crud! He uses the see through type filter.

 

[keegxwill]

I guess this post is probably dead, but did you happen to rebuild your carb and if so what results did you have? I am having similar problems. Just figured if ask before I dove into that.

 

[83kid]

I guess this post is probably dead, but did you happen to rebuild your carb and if so what results did you have? I am having similar problems. Just figured if ask before I dove into that.

Fixed it, engines a bit carboned up anyways so it has a dieseling issue unless im running 93 in it, but for the issues on carb tuning and such it fixed it, oh yea rebuild it with a kit from summit, easy to do