quote:

This is a true story, and just go's to show how much people love barth's even when there falling apart

Great story!

Ok, so over the last week I was the bath got pretty bad. it was missing when I gave it gas. It was dying at stop lights. And the backfires were so bad that in one parking lot 5 fire trucks showed up because they got a call on an explosion. the guy said they thought a transformer had exploded and called it in.
I did the tune up with all new plugs, wires, rotor, coil, cap. I even took off the valve covers and cleaned all that out then put on new gaskets. But to no avail. as soon as I started it up it backfired.
It got so bad that I had to drive with 2 feet so I could keep the idle up. went to one place and they told me that I needed to rebuild the carb or just put on a new one. So I drove it to the Walmart/Home depot parking lot (where I live a lot of the time) and just parked it.
I was at ends!! finally I broke down and bought a new Edelbrock carb. I didn't think the old quadrajet was worth saving. I hear unless you know how to tune them they are gas hogs!
Anyway as I was about to start working on it, this guy walked over to talk to me. I get that a lot with the barth. well as we talked he seemed to know a bit about what I was about to do. so when he asked me to start it I said ok. I already had the dog house off so it was easy to get at the motor.
He took off the frying pan and was looking into the carb. then he asked me if I had some water. So I gave him a bottle of water I had under my sink.
After I climbed back into the drivers seat he told me to give it some gas and hold it there. then he slowly poured the water into my carb!! The steam was amazing, and it shot a lot of black junk out the tail pipe.
After that it started running better. then he adjuster some things and told me it would be fine. he said I should just return the new one.
Anyone ever heard of this trick? I guess it cleans the carbon out.
He also told me that if I get the leak in my exhaust pipe (the donuts have blown out on both sides) fixed then everything should be fine.
So I'm going to get those fixed as soon as I can. But I'm not taking the other carb back until I'm sure he is right. Just incase...
So all this put off my working on the heat and windows until I get it running once more. there is only so much money in my budget at the moment. But once that's done I will be back on the heat with a vengeance winter is coming!

Hi!
I haven't heard of that "water down the carb" idea. Some of your description of the problems matches my problems this year. Some days the 454 would run as bad as any engine I have ever heard, and after replacing the fuel filters, it got me on the path to be running better than it has ever run.
happy motoring!
Matt

After I got off work last night I walked out to the barth and it started right up. It idled fine and drove fine. Or at least much better then it had been. I think that once I have the exhaust leak's fixed there is a good chance everything will be fine. The guy explained to me how the water trick worked if you want to try it. But he also said that if you don't do it right then you can destroy your motor. But its not hard to do. Just don't put to much in all at once. Then you have to know how to tune the carb. That's something that is now on my research list to find out about. let me know if you want details and I will post them.

quote:

I didn't think the old quadrajet was worth saving. I hear unless you know how to tune them they are gas hogs!

The most common problem with a Q-jet is a bad accelerator pump. Rebuilding a Q-jet amount to Dis- Assembling, Cleaning, and Re-Assembling using new Kit gaskets and parts. Setting float adj. is about the only adjustment needed other than idle screws.

I am not saying this is a job for everyone. Q-jets are more complicated than other carbs. Worn shafts/ bushing area where shafts come thru throttle plates can be a problem. On most M.H. they are not worn out like they are on daily driven cars.

If this is the original carb and is not worn out at shafts, IMHO I would have it rebuilt. You will end up with the best carb for both power and fuel economy.

Rebuilding your stock Q-jet keeps the proper cams, needles and jets for you application.

Fix your exhaust first. Check or replace vaccume lines. make sure your distibuter weights and springs are free and clean.

Good Luck.

When I redid my truck (1974 Chevy 1 ton dually with a small block 350/ turbo 400/ dana rear end) I took off the Q-jet because everybody told me they were junk. But now with a small amount of research I find that everything I thought I knew was wrong! I wish I had not pitched that carb. This time I'm going to learn how to tune the Q-jet. as long as it keeps running that is. I cant afford to much down time with that motor not working. being that I live in it and all hate having my house stuck in random place. Now don't get me wrong I like being in random places :P but not stuck there. And your right Doorman the exhaust leak is top of the to do list.

Ok so as it turns out I did have to take off the Q-jet because it had a crack in it. But I did get the exhaust fixed (only broke one stud)at the same time. So the barth and I are back on the road agen. But I am having a bit of a problem still because I'm still getting the rear back fire from time to time. Also with the new carb it seems to have lost all its pick up. at half throttle I'm only doing 30mph. At full throttle my top speed is 70mph. and it takes forever to get there!! Now I know its not a sports car. I don't expect it to be. but 0 to 70 in five and a half minutes seems a bit slow to me, even with the smaller trans. Any Ideas? Sadly those repairs took all the money I was saving for the new furnace so that will have to be put of for a bit.
Thanks to everyone for all the advice. Hope I can start working on it soon.

Backfire and low power would indicate a lean condition.

Make sure you have no vacuum leaks, be sure the carb is jetted correctly, be sure your vacuum lines are reconnected where they belong, and check to see if the secondaries are actually opening with high throttle. Also be sure the float setting is correct. All could result in lean out at high throttle.

Low vacuum could also reduce the amount of vacuum advance, further reducing power. Hmmm

Find a shop that has an qualified tech that can connect an engine analyzer with a exhaust gas sensor. An old Sun or Allen machine is what your looking for.(Old Speed Shop is good place to start.) This will tell you if ignition is good and advancing right, coil producing good voltage. what condition your compression of each cylinders are in. Could be burnt valves or stuck EGR. 15 min on an old engine scope and exhaust gas analyzer with some one that knows what there looking for can save lots of money being wasted on parts and labor guessing.

You may have to ask around to find someone. I needed a fuel filter install on my Q-Jet and had no tools with me. Auto shop told me they couldn't do the the job because the filter was in the carb. and it would take a carburetor specialist to replace it. That when I realized that most engines with carbs are considered historical vehicles, and many young car techs have never seen one.

One more thing, about the mid 70s GM produced a bunch of bad camshafts, Lobes went away quickly. The lack of zink in new oil has not helped anything.

quote:

Originally posted by Fulltimer:
Ok so as it turns out I did have to take off the Q-jet because it had a crack in it. But I did get the exhaust fixed (only broke one stud)at the same time. So the barth and I are back on the road agen. But I am having a bit of a problem still because I'm still getting the rear back fire from time to time. Also with the new carb it seems to have lost all its pick up. at half throttle I'm only doing 30mph. At full throttle my top speed is 70mph. and it takes forever to get there!! Now I know its not a sports car. I don't expect it to be. but 0 to 70 in five and a half minutes seems a bit slow to me, even with the smaller trans. Any Ideas? Sadly those repairs took all the money I was saving for the new furnace so that will have to be put of for a bit.
Thanks to everyone for all the advice. Hope I can start working on it soon.

Timing is a good start, do you have electronic or points? With a '75 I would guess electronic. One failure mode for some electronic distributors is screwed up timing. Another thing to check is whether the advance mechanism is free.
To the carb, is the accelerator pump spraying? If not you will take forever to get to speed and you may experience some backfire.