[BDD]

I have a 1972 GT that I haven't driven yet. It probably sat for awhile before I bought it. Initially the battery wouldn't charge and so the battery would get drained and car wouldn't start. I fixed that. The P.O. had messed up some wiring at the coil and alternator.
Now, when I start the engine, it doesn't idle well and stalls when I step on the gas pedal. I raised the idle speed just to help it keep running when first started. It will barely keep running when first started so I have to give it some gas. Just a bit or it will stall. I re-connected the manual choke to help with engine starting but that didn't fix the problem. It stalls if I close the choke too soon (I have to keep the choke out for longer than normal). It get's better when warmed up but is still not correct.
Maybe it's not getting enough gas, but seems better when warmed up.
There are occasional small "backfires" or "hiccups" when running.
The exhaust seems to smell bad, "acrid". worse than I remember from cars without catalytic converters. It does not seem to burn oil. Otherwise engine sounds strong.
Could it be old gas? I have not burned off the original tank. If so how could I tell and what is usually done about it?
Could it be a lead additive causing the smell?
I've read through some of the other posts and wondered if any body else had any other ideas.
I need to fix this before I drive the car.
Thanks.

 

[GTJIM (R.I.P.)]

Lean!

Sounds like the idle circuit is too lean - make sure the passages are clear.
If it has been sitting for a while it is likely to have oxidised gunk in the passages. So the carb needs a good cleanout - at the very least.
Also check the initial ignition advance is set correctly.
PS: Do you have the old Solex carb or has it been replaced?

 

[Dmcbrass]

I agree with GTJim. A good rule of thumb is to never mess with the Carburetor until you're sure the ignition system is working correctly. Since you're not familiar with the car, I'd recommend starting with pulling the plugs, and checking their gap. If you have a compression guage, you might as well check compression since you have the plugs out. Check dwell (point gap) and timing. If everything checks out OK I'd try adjusting the carb before you pull it apart. By the way which carbureter to do you have?

 

[Jim Branham]

gas

Old gas burns with an awfull smell and will make your car run like crap. How old is the gas?

 

[greensmurf20]

get this, i can be around fresh fuel fumes all day long and not get a headache, but as soon as i get around laquer or gas thats quite old, i get headache, lightheaded, dizzy, and horrable stomache pains!!! its some nasty stuff i'm tellin ya. i've been running my new GT of pop bottle cuz i'm dreading draining the quarter tank of laquer the gas guage says it has!!! yes gas guage works after 20 years of setting, haha.

 

[BDD]

Reply

My carburetor is a Weber with a manual choke. I'll need to set the idle speed, etc, in the right sequence at the proper time. Seeing that one of the vaccum lines fron the distributor was off, I've replaced that and I've hooked up the crankcase recycle hose correctly. These things didn't affect the problem but had to be done anyway.
I think that the car sat for quite awhile when the previous owner had it. So the gas could be quite old. I have no idea how old though. I don't think he ran it because I see evidence that he was trying to fix the wiring problem that I mentioned first (that kept it from running) with no luck. He also has a few (maybe one or two) wires of very small gauge that I'm going to have to replace. That's what he had at the coil and alternator and they were connected wrong besides.
Anyway, I've got to solve this gas/idle/accelleration problem. Then I can drive the car, get it painted, etc.

 

[BDD]

Also:

I had the Solex on my original GT in the seventies and eighties. I liked the water temp. choke but didn't like that carb. much otherwise. I'm glad this one has a Weber. As for exact carb I.D. I could read off some numbers on the casting and tag if it helps. It doesn't say 32/66 or whatever is usually used. It does say Weber, made in Italy.

 

[rangerrick]

Look on the throttle base plate for the number!

I also have a used Weber I'm cleaning up and rebuilding. I couldn't find any numbers on mine at first, just Weber made in Italy! At the base plate of the trottle body I believe on the short side of the carb I found the numbers stamped into the aluminum 32/36 DGAV 33A

 

[Dmcbrass]

If you suspect old gas drain the tank and start over. The great thing about the GT is that you get virtually every drop of gas out of the tank by taking the line loose under the tank. After you drain the gas put a couple of gallons of fresh gas in and take it out on the road. Did you check out the ignition system as I mentiioned in the previous post?

 

[BDD]

I have not checked the ignition system yet.
I looked over the carb. this weekend and compared it to another Weber that I have from a past GT. The one I currently have has larger barrels and square butterfly valves at the top of the carburetor. Haven't gotten the I.D. numbers off of it yet.
I noticed that the mounting bolts were a little loose as were the bolts that hold down the Weber adaptor (to use the standard Opel intake snorkel). I tightened these and started the motor up last night. It did seem to idle better after I had snugged those mounting bolts a bit.
I had to keep the choke closed for quite awhile. If I opened the choke too soon, the rpm's would go way down. Later, after the engine was warmed up I could open the choke and the rpm's would decrease but it idled fine at a slow speed. It also accellerated after warmed up with no hesitation.
Per some other posts, I put my hand near the top of the carb and noticed no rpm change. I also adjusted the mixture jet but didn't notice any rpm change. Wonder why that was? Hard to adjust if you can't get an rpm change.
Which way would I turn the mixture screw to lean out the mixture? It may be running rich.
I will check the spark plugs and probably replace them and check the ignition system soon when I have time. I have a dwell meter and a timing light. Just need the time to monkey around with it.
The exhaust is still "gassey" and obnoxious. I have to look into the reason(s) for that.
I'll probably drain off the old gas soon and replace it with new, high octane gas.

BDD

 

[Dmcbrass]

If you don't see a difference when you adjust the idle jet, the car is not running on the idle circuit but instead is running on the throttle. This means the throttle is adjusted open too far. Often this is caused by an engine that is not timed correctly. If the timing or dwell is off, the engine won't idle fast enough. It is common to see Opels with Weber carbs where the throttle has been opened up to correct for this problem.

Always check ignition settings before fooling with the Carbureter!!!!!

 

[Dmcbrass]

A further note: I have a 70 GT with a Weber 32/36 carb. I can tell when the points have begun to close up (dwell increasing) by watching the idle RPM. If my Idle RPM drops a hundred, I know that the points have closed up some. It's amazing how little a change in dwell (point gap) it takes to drastically affect idle speed. A properly tuned 1.9 with a weber carbureter should see a dramatic effect by turning the idle mixture screw as little as +/- 1/2 turn.

 

[Scott McDonald]

I noticed that the mounting bolts were a little loose as were the bolts that hold down the Weber adaptor (to use the standard Opel intake snorkel). I tightened these and started the motor up last night. It did seem to idle better after I had snugged those mounting bolts a bit.
BDD

If the mounting bolts for the carb are loose, you would surely have a vacuum leak. No carb can be tuned with a vacuum leak. Check for leaks around the carb base now that it is tightened. If vacuum leaks persist, re-gasket the carb base to intake.

Also make sure the vacuum line(s) from the distributor are sound. The little rubber connectors can go bad, and without pulling them off and inspecting, they may appear OK.

Check the brake booster for vacuum leaks. If you pump your brakes does your idle rpm increase appreciably? May be a brake booster-hose vacuum leak.

 

[BDD]

I just checked my carburetor tonight. It is a Weber 32/36 DGV5A serial number(?) 21866. The tin or aluminum tag on the carburetor says: Weber 711F FB A 0822 (or OB22) can't read my handwriting.
Do any of these other numbers relate to jetting, etc?

Good advice. I'll change the gas, check the plugs, check out the ignition system, timing, etc. I'll also check the brake booster for evidence of a vacuum leak before I fool with the carburetor any more. I guess I might have to readjust it anyway when I do a tune-up.
I set the idle speed stop screw faster awhile ago myself to keep the engine running when first started.


BDD

 

[Dmcbrass]

A good starting point on the Weber is to set the throttle stop screw 1-1/2 turns down from first contact, (make sure the choke is open and the throttle is off fast idle), and the idle mixture screw out 2-1/2 turns. You can tell you are getting the throttle screw too far out of range if you don't see a significant change in idle with a +/- 1/2 turn of the mixture screw. Make sure you check the timing after you set the dwell (point gap) and with the advance and retard hoses disconnected from the distributor.