Sputtering and backfiring

[nbrcrnchr]

Don't know what to do next or where to start. Just got through replacing the carb, points, rotor, and cap. She will start and idle, but as soon as I take my GT out, it starts to huff, chuff, and buck like it wants to quit all to gether. If I wasn't rolling it probably would. But it will sit there and idle. Anybody have any ideas

It had started to do this before I changed everything, but all of the above doens't seem to have helped much.

[Bo Mows]

Check fuel pump pressure (low), float level, vaccume leak (hose or intake). For vaccume leak i have sprayed wd-40 around the hoses and intake, if it cleared up, there you are. HTH

BTW-I live in Olive Branch.

Bo

[nbrcrnchr]

It may be a leak. I'm hearing something while not a whistle, but something which sounds like air being sucked somewhere. But trying to find it will have to wait. She who must be obeyed has other plans for the rest of my afternoon.

it only seems to want to stumble when the car is either under load or being revved up.

Not too far from the Big Metropolis of Tupelo. Had this car forever and it always seemed I was the only one that owned one in MS. It's amazing the number that are out there close by. Guess we need to see if we can get a group together.

[Al Olmo]

I had a similar problem some time ago, my vacuum hose at the servo was loose and had a leak, you might want to check that for a good fit.

[gtjames]

Make sure the dwell is set with a dwell meter. I believe the spec was 50 degrees.

Question:

When it idles, how is the quality of the idle? Does it idle high, rough, or what?

[nbrcrnchr]

It idles fine, except the idle screws on the new carb don't seem to have much effect.

[spdkilz02]

thats a sign of a vacuum leak then, if the idle screws dont do anything...

[wrench459]

you did not say if you changed the condenser

1. set the point gap to .018 inches about the thickness of a matchbook cover that will get you in the ballpark for dwell (50-55 degress)

2. set timing to 10 degrees corect me if I'm wrong at any time guys

turn the fuel mixture screw all the way in then back out 2 turns

start her up and set idle speed to @ 900 rpms

turn the air screw till best idle

if you have a vac guage you should have 18 inches at this point

[yellaopelgt]

See if the choke is set correctly, when its hot, it will idle fine if its closed but when you hit it, it will stumble and buck like you described.Been there done that.
HTH
Joe

[Wolf Spyder]

Originally Posted by nbrcrnchr It may be a leak. I'm hearing something while not a whistle, but something which sounds like air being sucked somewhere. But trying to find it will have to wait. She who must be obeyed has other plans for the rest of my afternoon. it only seems to want to stumble when the car is either under load or being revved up. Not too far from the Big Metropolis of Tupelo. Had this car forever and it always seemed I was the only one that owned one in MS. It's amazing the number that are out there close by. Guess we need to see if we can get a group together.

I've found a guy in Canton that has 4 (all non-running). He chased me down one day to "see one running". I've been told of another in Clinton.

Im game to form a Deep South Group. There are a few in southern Louisiana here on the board and another in Olive Branch.

I'm planning on going to the Blue Suade Shoes show there in Tupelo with a group from Mississippi Classic Cruisers. Maybe we can meet.


BTW if you have a solex the air hiss that you hear may not be a vac leak. Mine is quite loud in the carb, even at idle.

[2 Fast 4 U]

I've had a problem simalair to this the bolts on the intake and exhaust were lose when starting the engine all was fine when the engine was warm it didn't run good, stoped the engine to look and couldn't find anything started the engine again and al was good until it was warm again. Or maybe the timing is of

[opelwasp]

The problem with the Solex ancor...I mean carb. is the carb itself had a tendancy to warp. So whill its cool its great. But when its warm...warp. Theres no fix for that one. Just get a Weber and all is better, and more ompf to boot.

[nbrcrnchr]

It has a brand new weber and it's doing the same thing with it that it was doing with the solex. I had new Exhaust/Intake gasket and new muffler system installed to get it up to Tupelo. So I have a few places to look for problems. And No, I didn't replace the condensor.

I'll keep folks informed as to what I find. Thanks for the suggestions on where to look.

Bob

[LeftLaneGuy]

My wagon is doing the same thing, right now. It's got a rebuilt weber, all sealed up perfectly, no leaks, new ignition components, good compression, all vaccum lines good and/or plugged, and idles PERFECT. Only SOMETIMES does it do the cough/sputter/die thing. It's GOT to be something electrical. Here's a question: With a Bosch blue coil, I do not need the resistor wire any longer, correct? I've not changed that yet. It's my last item to replace.

dave

[jlthunder]

If the MC booster has a tear or pinhole you will experience a vacuum leak and will drive yourself bonkers trying to find it. Since this is the largest vacuum hose, disconnect it at the manifold and plug the manifold. If it goes away, you found narrowed it down to 2 possiblities. The hose and the booster. reconnect it and disconnect it at the booster and plug the line. If it goes away, it is the booster, if not it is the hose.

For the other lines

Remove one vacuum line at a time and plug it at the manifold. This should help narrow it down. If the lines are old, replace the lines.

[2 Fast 4 U]

I remember when driving at high speed on the freeway the car began to backfire alot had to reduse speed and when I pushed the peddel it started to backfire again.
pulled up onto a parking place and adjusted the timing a bit earlyer and my problems were gone

[ronskydivepops]

I had the same problem with my GT recently. The weber didn't seem to change much when I tried adjusting it and when I tried to floor the gas it would bog down and want to die. If I let up on the gas it would smooth out and run fine. Idled fine but, was hard to start up. I had the intake/ exhaust manifold planed and still no change. Put in two intake/exhaust manifold gasket and the weber adjusted beautiful. Then I adjusted the float level and the bogging went away. Only drawback was after it started running the way it was meant to, I realized I needed a new clutch, and now a new tranny. Never seems to end.

[wrench459]

I've sent a message to a friend of mine who might be able to shed some light on this subject
He's an old Sun technician who's very smart.
Can anyone tell us the proper microfarad rating for the condenser?

[nbrcrnchr]

I've cleared up the worst of the backfiring. I hadn't tightened down the carb very well and had to get some of those stubby wrenches to get to a couple of the bolts. It's better since I have tightened down the carb and replaced the hoses. Still working on clearing it up. Going to see how it does as I flush out the old gas.

Next project is to replace headlight wiring.

[scrapman]

My GT has some of the same symptoms. Idles rough, but is strong when driving. When at a stop light, the idle is not even. Give it gas and a slight hesitation before picking up. The biggest problem is randomly I can be driving down the street or highway and regardless of the speed it will start cutting out and then die completely. Happens often when putting a load on it like going up a hill. After a while sitting at the side of the road it will start up and get me where I'm going. One day it runs great, the next it pulls this stunt. I've already pulled out half my hair trying to get to the bottom of it. I've changed points, plugs, condenser, fuel filter. Next step is an electric fuel pump. I checked the pressure out of the pump and at idle it is giving about 4 and 3/4 pounds. Also pulled the mesh filter out of the tank in case it was blocking fuel. Any other thoughts would be welcomed. Might solve both our problems. It does have a new Weber 32/36 on it.

Scrapman
Rick
71 GT, 73 Manta Luxus

[2 Fast 4 U]

Maybe the carb is getting to warm, on the solex carb there is a "hot spot" valve on the base of the carb, this is a bimetal plate that curls open when to warm and opens a port to let "cooler" air in. Maybe it's that, maybe not, it's just something I was thinking of