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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: RE4PER on August 14, 2015, 01:01:51 am
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Ok so one day I was driving and my truck shut off. Wouldn't start back up come to find out no spark. Did alot to fix and nothing. Stabbed a new distributer in and spark. After that she wouldn't Idol let alone drive. She's timed 8 degrees after TDC fuel pump works fine so I figured carb. Stock Rochester rebuilt it still nada. Messed with it I'll today now I'm waiting on a new carb. I'm just worried the new carb won't fix her. This is my daily driver and I'm military so any advice is awesome.
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Can you turn the distributor and get it to run smooth?
You can't always go by the timing marks on the harmonic balancer. Sometimes the outer ring on the balancer slips and throws off the timing mark.
Just a shot in the dark, but its free & easy to check.
If the truck was running good before the no start issue, I wouldn't think that the dist & carb went bad at the exact same time. If a new dist got the truck to run, I'm thinking its a timing or firing order issue.
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with fitz on this. if the distributor fixed the problem its
not a timing, misfire or firing order issue
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with fitz on this. if the distributor fixed the problem its not a timing, misfire or firing order issue
X3
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thanks bd lol
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I am guessing the 8° ATDC is a flub-up and you really meant to say 8° BTDC! It sounds like you got it running again with a new distributor, but that it isn't running correctly. That would lead me to believe that something is off with the timing.
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Ok thanks for the responses. Timing is kinda hard to do unless the truck runs. You crank her she turns over but after about a few seconds to few minutes she shuts down. I've played with the carb adjustments to no success.
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My truck is a 79 c10 Silverado with a 5.7 350 hei distributer if that helps at all.
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you dont need it running to get it in time. if you want to tune it good you need it running. #1 plug wire is normally in the 5 °'clock plug on the cap then you run the order from there 18436572
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All the wires are in the correct spot on the cap. But she wouldn't stay running unless I was on the gas. Regardless of what I adjusted.
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Let's start at the beginning.
The truck was running good and it just died driving down the road? You determined it wasn't getting a spark so you installed a new distributor. At this point the truck starts, but barely runs, correct?
You mentioned that the carb was rebuilt. Was it rebuilt before or after the truck died?
Like I mentioned earlier, Its high unlikely that both the distributor and the carb stopped working at the same time. I think we should concentrate on the ignition system.
You said you put in a new distributor. What brand is it?. There is a chance that its bad. Stranger things have happened then a new part being faulty.
I know its no fun when your daily driver don't run.
What would I do in thiis situation? (I've been through this before).
Remove the #1 spark plug ( you may want to check all of your plugs) and unplug the power to your coil.
Ask a friend or neighbor to help you for 30 seconds. Place your finger over the #1 plug hole as your helper taps the key in short burst to bump the motor over. When your finger is pushed off the hole, the #1 piston is at top dead center on the compression stroke. Pull the dist cap. Is the rotor pointing to the #1 plug wire?
Now check your timing marks on the harmonic balancer. It should be set at zero, or close to it. Like I said in my first post, you can't always trust the timing marks, that's why I'd pull the dist cap to verify everything lines up.
Many times when removing/replacing the dist I have to use a long screwdriver to line up the oil pump shaft So everything lines up. If you just drop the dist into place, it usually is off a little ( ever see a dist where the aluminum vacume port is aimed at the firewall?)
As Ehjorton mentioned, you said your timings set at ATDC, was that just a typo? As he said, it should be set at BTDC.
The HEI is a great distributor, but like everything else, if its not working right, it will drive you crazy.
Keep us posted on your progress.
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Ok so yes it was a typo when I installed the accel distributer the #1 was at TDC as well as the mark on the Ballenger was very close to 0. Got it to timed to 8 degrees after this. The truck fires but it idols ok then you can hear the rim drop then pick back up (without touching anything) then drop again until it shuts off. At one point I got her running drove and if I got off the gas she died. If I tryed to go over 25 died. Pulled over to see what I could do and I couldn't get her to stay running at Idol again. The carb was rebuilt after the distributor was installed. And with what research I did was pointing to carb. Pump is giving fuel with no problems plugs n wires are 3 months old distributer brand new. So tweaking with the carb my helper lost a spring from inside and snapped one of the choke rods hence y I'm getting a new one. But before this I could keep her running if I physically closed the butterfly just a hair.
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How did it run when you closed the choke a little?
What are you buying for a new carb?
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sounds like a major vacuum leak. could be at the carb or could be a intake or hose leak
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What is the carb? If you bent , broke a choke rod ?
You mean inside or outside of the carb?
If inside its not going to run right no matter what you do. Bent broken primary rods will cause all sorts of issues on carbs
This is a common mistake made on quadrajet rebuilds. Assuming you have a quadrajet.
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When I closed butterflies a hair it ran fine. Let em open where they were and back to the same ordeal. New carb is a stock replacement. I'm divorced and can't afford a nice one. Atm just need her drivable again.
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Yes it's a quadrajet and it's the rod that is inside the carb.
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It will not run correctly if that's the case unless you replaced the rod with a matched rod. Even if there bent you will have problems. The power piston is probably being held open causing richness and surging etc.
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Well just got the new carb going to install now. Any tips I'll need?
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The carb was rebuilt after the distributor was installed. And with what research I did was pointing to carb. Pump is giving fuel with no problems plugs n wires are 3 months old distributer brand new. So tweaking with the carb my helper lost a spring from inside and snapped one of the choke rods hence y I'm getting a new one.
Was the "helper" that lost the spring and broke the choke rod the same person that rebuilt your carb?
If so, I'd like to change my answer.
Assuming that your motor has no internal issues such as a worn cam or jumped timing chain, it sounds like your heading in the right direction.
With a good ignition system, all you need is gas & air and it will run.
Let us know if the new carb solves the problem.
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Carb got her idling now to keep her running while in gear
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Carb got her idling now to keep her running while in gear
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So is It running & driving now?
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For the most part. She idols and drives but hit the break shuts off. Driving a automatic like a stick. Put In netrual feather the gas while on break to keep her going. Any thoughts?
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Sounds like your brake booster is leaking.
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Like vacuum? Would that cause it to shut off in gear?
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Also not 1oo% on if I did my vacuum lines right. New carb has different ports. Ended up plugging vacuum advance to keep her going. Correct me if I'm wrong but u plug advance while timing correct?
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if you hit the brakes and it dies or you hear a hissing sound then the booster is bad. it could also be running poor and any leak like a booster will kill the engine
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Yes, you unplug the vacuum line when you set the timing.
Got a few things to check.
Does the timing change when you disconnect the vacuum line from the dist? (It should).
Did you set the iddle mixture screws using a vacume gauge?
How does it run? (besides the stalling). Can you shift it in & out of gear while stationary with your foot on the brake pedal without it stalling?
Does it iddle well in gear?
Is the choke working?
Sounds like your getting close, your allot better off now then you were this morning.
A little fine tuning on the timing and setting the iddle can make a big difference.
Like Irish said, pay attention to your brake booster and check it for leaks.
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Ok no screws for air fuel on this carb it has a dial on the passenger side for rich lean. This carb has a heated choke. Not 100%sure what the other one had. Before we removed the vac advance and plugged timing did change. With it unplug put it at 8 degrees. Yes advanced hooked up it would shift gears while stationary. But while moving (in gear) she can go about 25 3o without my help (on the gas) however stopping she shuts off. We temporary fixed this with Un hooking advance and plugged it. So with that plugged and putting her in netrual when stopping I can drive her with feathering the gas every now and then. No vacuum gauge was used due to I don't have one. Kinda spent after getting a new carb and distributer.
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Once again thanks for all the help so far
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The dial thing is the choke adjustment. Rich/lean is simply the length of time the choke stays on by increasing or decreasing spring tension.
Rich tighter, lean looser.
The mixture adjustments are probably covered with caps of some sort that limit or prevent adjustment. They can usually be removed.
You said by removing the vac advance
hose an plugging the idle is more controllable but still stalls. Doesn't make sense to me.
Where did the carb come from? Pics?
When you go from park to in gear how does this affect idle speed? How much does the rpm change? Mechanical advance coming in too soon can cause idle trouble.
Where did the dist come from?
If you want to eliminate the brake booster just plug the line to the booster and see what happens but you will not have power brakes.
If timing and ignition are good stalling when you come to a stop sounds like a large vac leak or not enough idle fuel.
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Both came from auto zone I will try to figure out how to send pics
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Me personally would cap off all vac lines on the carb that go to anything other the the carb itself and see if the idle improves.
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One vacuum line that gets overlooked is the transmission vacuum modulator. That line normally goes directly into the intake manifold and is located between the carb and distributor. The line is large enough in diameter that if it's broken or split somewhere, it can definitely cause rough off-idle conditions and certainly lose it altogether when it's in gear and you're stopped.
To be certain the line or modulator isn't leaking, just pull it off the manifold and cap it until you're sure.
Mack.
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You keep saying 8 degrees AFTER. You don't mean that, do you?
Is your vacuum advance on ported vacuum or manifold vacuum? It should be on manifold vacuum; ported vacuum will make it idle like crap, especially if the timing is off.
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My vac advance on the old carb went into the carb. The new carb is set up different is the only reason I an not sure if lines are right. Didn't come with a diagram. But it's a stock replacement but a different choke.
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from my experience the vacuum port on the base of the carb is manifold and the one thats a little above that is ported. dont know if its true for all carbs but i know it is on the edelbrock
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I have actually seen a time where plugging my vacuum advance into the true manifold vacuum made it idle like crap. I found out that the idle mixture was way incorrect. Emissions controlled engines ran a lean mixture, late ignition timing and no advance on the distributor at idle.. hence, "ported" vacuum which is only present at off-idle conditions, ie, when the throttle plate is opened.
If it's a "stock replacement" (Quadrajet) then I have experienced rough and super poor idle because of a lean mixture. I just went though this on my 350 engine and finally fought it long enough that I bought a new carb, which is working flawlessly now.
What kind of carb is it? If it's a Quadrajet, it will say so on the driver's side with a stamp in the aluminum.
If you're trying to figure out which is ported vacuum or straight manifold vacuum, if you can get it to run at idle speed, just stick your finger over the vacuum port. If it's sucking vacuum at idle, it's manifold vacuum. If no suction, it's ported. ALL your vacuum lines should go to straight manifold vacuum, unless you're running emissions control and you're running ported spark, with a lean mixture and late ignition timing (by late, some of these engines ran at zero base timing, I have even seen some at 2 degrees after TDC !!) Otherwise, everything goes to manifold vacuum, even the advance on the distributor, with the base timing set at a good starting point of 10 degrees BEFORE TDC and a good idle mixture to keep it running smoothly when you plug the dizzy advance canister in.
Take some pics of the carb.
Mack.
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I took pictures but can't upload for some reason. The carb was purchased at autozone. Part number 3-3622. You can see it on there website. It's a heated choke. So just to be clear. Timing wise since it seems to be coming back to timing, I unplugged vacuum advance from the distributor. Plugged the line turned cap till the balancer was at 8 degrees. Plugged vacuum advance back into the distributor. Upon doing this she ran fast as heck in Idol. With the Idol screw pulled out a decent amount. But still had the same issue of applying breaks (which requires me off the gas) shutting off. How I get around is I pulled vacuum advance off and plugged it. As well as when stopping shift in netrual and feather gas if needed. Shift back in drive when I'm ready to go again.
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I'd pick up a vacuum gauge and set the timing with the gauge
There are some good YouTube vids for setting with a vac gauge
Basically you just move the distributor slowly while it's idleing and watch the gauge and leave it where it makes the highest vacuum
And look for some large vacuum leaks
Could be brake booster leaking or somewhere
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OK I'll try that.. Where do I get the gauge
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OK I'll try that.. Where do I get the gauge
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Any auto parts store should have one
I never pay any attention to the timing light
I just advance it a tiny bit and run it up the nearest hill at full throttle
Then advance it a little and do it again
Until it rattles The retard it just a bit
The vac gauge will set it fine. And will also show up other problems
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OK now I'm confused just put out a fire on my truck. #6 plug wire was on fire while I was driving. What would cause that?
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