rough idle

[nvr_di]

Hi guys got an issue that started with just a rough idle but now it wants to die at stop lights and im having to drive with both feet to keep it running.
The background story is I parked my 69 c10 for 2 years or so and I just recently got it running again. It was running great except right before I parked it, it overheated but I didn't really think about it as it was my second vehicle at the time.
A couple of weeks ago I tossed some new fluids in it and it fired right up! and it ran fine accept for a bit of a rough idle and a surge when taking off from a stop.
This weekend I put some new plugs and a new cap and rotor. While we were working my buddy did happen to notice a bit of what seemed like oil under the truck. It was new oil color but had the feeling of oil and water. We couldn't tell exactly where it was coming from but it looks like somewhere on the back of the motor. I fire the motor up and it seemed to run great! The idle was better and no more surging. So of course I open it'd it up on the freeway and it ran great! Then I get off and it dies while stopped at a light. This morning I put in a new fuel filter just in case but of course nay.

Any ideas what I should look at next? Is it sounding like a head gasket?

Thanks I appreciate the help!

[ed70]

did you check the tank to make sure there wasnt any bad gas left over or anything like that... debris can be pretty harmful... ow bad was the fuel filter when you checked it... i would check there... what about the carb does it have clogged jets??? i dont know for sure about a head gasket... the symptoms and such the best way iv heard of checking for one is to check your oil and see if its foamy or milky and see if the radiator is gurgling with out the cap on it while the truck is running... just to help out... good luck...

[nvr_di]

Yea I was wondering about the gas issue. So there was say around 1/8 of a tank when I parked it. When I fired it up I filled the tank with fresh gas and added a fuel cleaner/octane booster.
Im hoping that was enough to delude any bad gas left in the tank.
The filter had a few debries in it and was brown in color but who knows how long it had been before the filter was changed before me.
I was going to check the sock in the tank and see if it was clogged. also i'll check the oil as well. Do I have to do a full oil change to be able to tell if theres water in it?
How do I check the jets? im an efi guy so im an idiot when it comes to the carbs.
Thanks for the help ed

[texanidiot25]

Put a fuel filter before the carb, and keep a spare on hand. Sounds like you've just got junk running through the system, and it's clogging the idle circuits in the carb. Trust me, my 1st month on the road was full of dirt-in-gas fun, including starting my truck while in the middle of a major inter section, and limping it over 5 feet to a marked off section of road (for the freeway under pass U turn to have room to merge) and then by the grace of the Chevy gods got it fired up long enough to rev it up, throw itin gear, and rip over to a parking lot before it died again.

Got so much junk in the carb that it couldn't idle or go slow. Later time some junk got the float stuck and my truck was running so rich it couldn't idle, or restart.

Maybe 7 fuel filters later, I now know my fuel system is clean But if that tank was stored with out fluids in it, it can surface rust inside, and when you filled up the tank, it washed off that layer of rust. That's my theory for my problems. Keep fuel filters on hand, and pull the carb apart and give it a good cleaning at some point.

[68gmsee]

I agree with what's been mentioned. Happened to me also after my truck sat for a while.

Since you say it overheated and to be on the safe side, I would do a compression check on the cylinders to make sure you have approximately the same compression on all cylinders.

Also, check to see if you're using more water than normal, check for bubbles in the radiator and maybe see if a shop can do a leak test on you cooling system.

Don't overlook leaking vacuum hoses and carb gaskets. I had to replace mine on my 68 and also had to open the carb to clean a lot of gunk from inside the bowl area.

[tim21391]

my dad bought a 67 mustang that sat for a few years.. and it started..ran rough..vibrated real bad..had to keep your foot in it to keep it going..pulled off valve cover and found three rocker arms that wernt connected..push rod stuck in a valve...connected those back up and it ran fine.. i dont know if this could help you but i thought id put my .02 in...it also had blown head gaskets..

[JHART]

Does the truck have an after market cam? Could be a vacuum issue also.

Start the truck and pump or hold your break peddle. Does the rpm increase or steady out?

[MrC1]

Not sure if this is it, but mine does it so worth a check.

Sometimes after running WOT, my secondary throttle blades stick slightly open. This causes fuel to dribble into the intake and it starts chugging.

If this is happening, you'll notice that the exhaust is black. The simple fix is to jump out, throw open the hood and just push the blades closed with one finger by pushing the arm on the side of the carb towards the back of the truck. It will recover and smooth out in a matter of a few seconds.

Worth a shot!

[nvr_di]

I appreciate the help guys!

Yea that wouldn't surprise me at all if something was in the fuel system. I have a filter right before the carb and I just changed it. I'll pick up a couple more filters and keep them in the truck.

I'll try and do a compression test this weekend and I'll check for bubbles in the radiator.

I sprayed the base of the carb and the intake manifold with carb cleaner and I didn't hear the rpms change or anything so I'm fairly sure the gaskets are good. But a vacuum leak could be possibility.
Where should I look for leaks? I don't have power brakes.
Also it does have an aftermarket cam but I have no idea what the PO put in it. If I had to guess I would say its the RV cam. Its mild at best.

I haven't noticed any smoke from the exhaust. If anything, maybe a little gray but very little and it normally goes away after a few seconds.

I'd like to clean the carb but I'm not exactly sure the right way. Its got a Edelbrock 1406 on it. And I'm a bit worried about getting it adjusted correctly after taking it apart. Ive sprayed it with carb cleaner while running like Edelbrock's website suggested but it didn't make much difference and I'm sure that's no substitute for a real cleaning.

Forgive the stupid questions but this is my first carbureted truck. I downloaded the owners manual but still have a few questions.

I will have to replace the carb to intake gasket if I pull the carb right?
If I take it apart to clean it do I have to put a rebuild kit or replace any gaskets or can I just slap it back together?
I also read I could blow compressed air to clean the jets? Where exactly do I do that at? And does it have to be compressed air?
Also any other tips or anything I should know?

Thanks again guys!

[texanidiot25]

If your lucky and careful, you can sometimes take the carb apart with out tearing anything. Same thing on the intake gasket to the carb. I've had my carb off a few times with out tearing it. And have had it apart with out tearing the gasket. But of course, it's a rochester..

The day I got junk stuck in the float, my dad pulled this trick and it worked perfect until the next time I got trash in it. Start it up and get it to run. Have someone pinch off the fuel line before the carb (if you have any rubber liens) with a vice grip. And run the carb until it stalls. This ran my carb dry, and got the dirt out of where ever it was caught. Once the fuel line was unblocked, the truck started right up and idled perfect again.

[fdbdw]

I had the same issue, rough idle died at stops and I was also driving with 2 feet, if you have points i would suggest checking the dwell should be 31-34 check your manual if you have one if thats the issue i would suggest putting on a new set of points ( cheep and easy to do), If you adjust the dwell remember to check the timming after, when I had this problem I thought is was a vaccum leak also but once I got the points set correctly it ran like a dream, hope this helps

[tim21391]

ya take bowl off the carb and wiggle the float that might work.. it worked on mine as well

[JHART]

Originally Posted by nvr_di

I appreciate the help guys!


I sprayed the base of the carb and the intake manifold with carb cleaner and I didn't hear the rpms change or anything so I'm fairly sure the gaskets are good. But a vacuum leak could be possibility.
Where should I look for leaks? I don't have power brakes.
Also it does have an aftermarket cam but I have no idea what the PO put in it. If I had to guess I would say its the RV cam. Its mild at best.


Thanks again guys!

Had a RV cam in mine and was nothing but issues for me. Check the vacuum line running to your dizzy from your intake. I'm no expert either just had similar issues with mine.

[nvr_di]

Ok so ive tried a few things..

I looked in the radiator while it was running and warm and I didnt see any bubbles. Im hoping thats a good sign.

I noticed when I held the (forgive the extremely technical name) flap thing on the top of the carb closed it seemed to run better. That points to a lean issue right?
Thats what it seems like to me when driving it. it feels like no fuel no fuel no fuel FUEL. Then my neck breaks from it surging forward.

So I pulled the air mixture screws, counting how many turns so I could get it in approximately the same position when I put it back in.
Cleaned them and sprayed cleaner in the holes. No Change.

But when I turned the one on the right counter clockwise (opening it I think) the rpm increased and it stopped wanting to die.
It still doesn't idle right but I'm pretty sure its a carb issue and I need to take a part and clean it.

Can anyone give me any tips or point me in the right direction so I can get it taken apart and put back together correctly?

Thanks again guys!

[68gmsee]

Just dive into it. No guts no glory!

Just kidding. But, that's what I told my neighbor and he did it.

I'm not an Edelbrock person, but while you have the fuel line disconnected, make sure the fuel pump is pumping enough gas. A good way to check is to have someone crank the engine while you hold the fuel line in a clear plastic container of sorts (I've used a quart milk jug).. It should have good strong pulsing gas flow.

[nvr_di]

Originally Posted by 68gmsee

Just dive into it. No guts no glory!

Just kidding. But, that's what I told my neighbor and he did it.

I'm not an Edelbrock person, but while you have the fuel line disconnected, make sure the fuel pump is pumping enough gas. A good way to check is to have someone crank the engine while you hold the fuel line in a clear plastic container of sorts (I've used a quart milk jug).. It should have good strong pulsing gas flow.

haha oh im about to go balls deep into this 1406. The likes of which its never seen!

Thanks for the tip on the fuel pump. I've wondered if the pump was good this will be a good test.

[fdbdw]

do you have points distributor or hei, if points I would make sure they are set right before doing anything, sorry to harp on this but if the points arent set right no matter what you do it wont run good, if you dont have a dwell meter you can do a aproximat by opening the window on the front of the distributor using a screw driver or allen wrench slowly turn it clock wise until it starts to run rough then turn it back a quarter turn then set your timming. If your running points and dont have a dwell meter it would be very benificial to get one, a dwell/tach/volometer anylizer can do alot with these trucks and well worth the money

[nvr_di]

No problem fdbdw harp away! Its got points and that is definitely on the list. im gona try to get to it this weekend depending on how other things go. i'll see if I can pick up a meter and a timing light.

[dznucks]

you can go to edelbrocks website and they have good technical info on the 1406. I have a holley and a demon that i never could get to run right. then i bought the 1406 and its my favorite of the three. there extremely easy to work on and theres not alot to them.

You mentioned you turned the right air screw out and it wanted to idle.
It sounds like the carb is out of tune. It is typical for the air screws gradually turn and cause the carb to come out of tune with these carbs. you need to adjust both the air screws until you get your highest vacuum reading. The tech info tells how to do all this and more. check the link out below, look for the 1406 Carb Owners Manual.

seeing as how it sat for a while you might want to take of the top of the carb and make sure there no dirt in the bowls and make sure your floats are not sticking.



http://www.edelbrock.com/automotive_...all/1000.shtml

[nvr_di]

Originally Posted by dznucks

you can go to edelbrocks website and they have good technical info on the 1406. I have a holley and a demon that i never could get to run right. then i bought the 1406 and its my favorite of the three. there extremely easy to work on and theres not alot to them.

You mentioned you turned the right air screw out and it wanted to idle.
It sounds like the carb is out of tune. It is typical for the air screws gradually turn and cause the carb to come out of tune with these carbs. you need to adjust both the air screws until you get your highest vacuum reading. The tech info tells how to do all this and more. check the link out below, look for the 1406 Carb Owners Manual.

seeing as how it sat for a while you might want to take of the top of the carb and make sure there no dirt in the bowls and make sure your floats are not sticking.

right on man thanks. I picked up a vacuum gauge today and im looking to tackle this tomorrow.

[Highsteel]

Originally Posted by nvr_di

Ok so ive tried a few things..

I looked in the radiator while it was running and warm and I didnt see any bubbles. Im hoping thats a good sign.

I noticed when I held the (forgive the extremely technical name) flap thing on the top of the carb closed it seemed to run better. That points to a lean issue right?
Thats what it seems like to me when driving it. it feels like no fuel no fuel no fuel FUEL. Then my neck breaks from it surging forward.

So I pulled the air mixture screws, counting how many turns so I could get it in approximately the same position when I put it back in.
Cleaned them and sprayed cleaner in the holes. No Change.

But when I turned the one on the right counter clockwise (opening it I think) the rpm increased and it stopped wanting to die.
It still doesn't idle right but I'm pretty sure its a carb issue and I need to take a part and clean it.

Can anyone give me any tips or point me in the right direction so I can get it taken apart and put back together correctly?

Thanks again guys!

Both of those screws on the front of your carb are Idle Mixture Screws, one for each side of the carb. Instructions for adjustment can be found in the link below
These are very good carbs and really very easy to work with, IMHO.

Below is a link to get the manual from Edelbrock, which should give you every confindence to do anything needed to this carb.

1406 owners manual

Let us know how things work out and good luck!

[nvr_di]

Well I pulled apart the carb and cleaned it this weekend and its still not perfect but it made a big difference. idles better and the throttle response is back.

Im not convinced the carb is adjusted properly. I couldnt find any place to connect my vacuum guage to. all the ports on the intake manfold are plugged so I wasnt sure which one to connect it to.
Does it matter?
Also how do I know when the choke is adjusted correctly? it seems to idle pretty high when the choke is on.

Up next new points.