Possible Carb Problems??? Help!

[bcoxsey]

I have a 1978 American Clipper with a dodge 440 and a Carter thermoquad. I have been noticing that under any kind of load the engine bogs down like it is running out of fuel and starts to cut back and may even backfire. I had a real hard time pulling the cuesta grade near San Luis Obispo, CA (if anyone is familiar with the area). I have already changed the spark plugs, wires, cap and rotor (for a different problem - it was missing, and that fixed that problem). I have had people tell me to replace the ignition coil and ballast resistor, as well as tell me the motor may have a bad valve... I think it may be a fuel related problem.

I was also told that those types of ThermoQuad's have a lot of plastic parts inside of them and they go bad or something. I was also told to convert the carb to a smog legal holley carb and I would have a lot less trouble in the long run, as opposed to rebuilding the ThermoQuad carb. I have almost positively ruled out any type of electrical problem, as the engine runs fine at idle. My only other thought(s) are that the fuel pump may not be supplying enough gas to the carb (even after having changed the fuel filter, which was not clogged at all), or the vaccum advance on the distributor is not working right or is sticking. I would appreciate it if anyone has had the same problems with their dodge motorhomes could email me at ( bcoxsey@hotmail.com ) and fill me in. I am thinking I will try to replace the fuel pump, and I have even had some crackpot/backyard mechanic-wannabe tell me the ballast resistor was bad (don't really trust that guy, but is it worth trying?)... I need some help, and I do not wish to spend an arm and a leg at a garage to have them charge me $100 or more to tell me what I may already know. If anyone has any insight into this problem, please feel free to send me their thoughts. Thanks!

[Plante]

Brian - I have the same unit you do and had the same basic problem.  First I installed a new Edlebrock 750 cfm carb.  It ran better but still had the same problem; next came a new distributor which also helped - but what helped the most was installing the Edlebrock intake manifold.  It no longer backfires or acts like it is starved for gas.  (Note) While putting everything back together I pinched a wire in the bracket that holds the coil.  It caused several wires to melt together.  Fortunately I was just pulling into the dealer for regular service.  My carelessness caused shorts and ruined my wiper motor and the small ignition module above the battery.  $$$$$$$

[Richard Peterson]

If you haven't already, be sure to check the vacuum advance as well as the timing itself.  Once you are sure of the timing, you can look to the carburater as a problem.  Make sure it is mounted tightly, the four nuts have a way of loosening up.  Make sure the accelerator pump is working as you need the extra shot of fuel to begin moving or change speed.  When your carb is working properly, it will suprise you with its performance.  You should also check all the vacuum hoses for possible leaks.  

[bcoxsey]

Thanks everyone... I have owned this Clipper for over a year now, and have been meaning to join the club, but money is tight right now, and I plan on sending my application forms in sometime soon. Thanks for the helpful information. I think I am going to try replacing the coil, checking any and all bolts, etc. for the carb/intake for tightness.

One other thing I have noticed is that the engine makes a sort of "hissing" sounds (similar to a vaccum leak) but my uncle who was a winnebago mechanic in the 1970's through the early 1980's and is now a Chevrolet tune-up technician (with multiple ASE certificates) richened the mixture and we covered the carb and it made no real difference so he says it probably is not a vaccum leak. I think the sound may be coming from the A/C unit... I consider myself to be rather mechanically inclined, and being from a family of mechanics (my great grandfather, my grandfather, and my dad and all of his brothers were mechanics) I think I can eithr fix it myself or have one of them help guide me along the way. It's just frustrating not being able to pin-point things as easily as they can. I chose not to be a mechanic (from the advice of my dad who has back problems due to his profession) and studied engineering. Anyways. I truly appreciate all of your suggections... Thanks everyone! ;o) If anyone else has any other suggestions for me to try, I will gladly accept them. Thanks again!

[bcoxsey]

Oh, I forgot... I looked at the lower pulley to see if there is a timing mark on my motor, and having a 1966 mustang that I have taken apart a few times, I know what to look for. I can't find anything that would indicate anything as far as timing is considered. Any help here? Maybe I should clean up the pulley, but even so, there should be a mark or notch to use to see when the timing light passes the mark every TDC of the rotation. Any help here? My unit has electronic ignition, right? Or are there points, I did not see any when I changed the cap and rotor, but it was hard enough to just get to the darn thing, let alone look inside of it. Boy, let me tell you, the spark plugs are no fun to change either! Thanks everyone!  

[handyman]

Check the hole over your fly wheel houseing thats where dodge put a second set of timing marks because you can't see the front ones unless you have a mirror

[phyllaurie]

Dear Bryan, This may sound really simplistic, but try a can of SeaFoam. I just yesterday got the pink slip on a 78, 440. Have been trying to start it for a couple weeks. Primed the carb to get it started, and it would run till the carb ran out of gas but there seemed to be nothing from the gas tank reaching the carb. No smell of gas, no nothing. I had the fuel pump changed. It ran till the mechanic left, then died and would not start again. A friend from Minnesota told me about SeaFoam and I found some at Winchester Auto. Wouldn't start today, so I primed the carb with gas to start it, and warmed it up a bit, then followed directions of slowly poring SeaFoam into the carb as it ran, then turned it off to wait 5 minutes. Immediatly I began hearing a kind of creaking noise, a low moaning, more like the frame of my other van when I do a weird corner. Anyway, after 5 minutes it started right up, blew TERRIBLE greyish/whitish smoke out of both exaust pipes for about 5 minutes (the can said it will do that) I let it run a bit more till the exaust was clear, turned it off, started right up. Started it several more times, no problem, ran great. This American Clipper has only 34,440 miles but has sat for most of 15 years only started occasionaly but never driven anywhere. It's just purring now, all because of about a third of a can of SeaFoam. I poured the rest into the gas tank. Like I said, simplistic, and I haven't driven it anywhere yet, but I couldn't even get it started before. It's worth a try. I'm putting SeaFoam in my regular van tomorrow!

[bcoxsey]

Well, I managed to fix the problem... I wound up finding the problem to be a slit or hole in my fuel hose from the tank to the tubing underneath the unit by the spare tire area... Apparently, someone changed part of this 3 foot or so long section and they did not change the whole section from the tank down to the permanently affixed line under the motorhome. Well, the placed a small section of tubing as a union between the old section and the new one they replaced. Anyways, I was running my motor (like I do every week or so to make sure it stays charged and just to keep the juices flowing (so to speak), when I decided to look underneath the motorhome. I saw a bad section of hose, and I squeezed the good section and when I let go, I heard a "sucking" sound like air being sucked through a straw. I wound up spending about $2 on the new hose, and a painful 2.5 hours dropping the tank with the use of a floor jack and some wood. Man, I need to get some more tools and an air compressor! ;o)

Then I took it out for a test run and no more sluggish running for my clipper. I can't wait to go take it out. I was so excited, I installed a DC-AC invertor for our TV and VCR we have in the unit... Hmmm... Anyone know any good camping spots along the northern part of the Central coast of CA??? We liked to go camping at Jalama Beach near Lompoc (check out this website www.JalamaBeach.com for some info)... Well, thanks everyone for all of your help and suggestions... Looking forward to running into some of you guys (and gals) on one of my cmaping trips in the future.

[junebob]

Bryon- Thermoquad Carb.    
 You should consider all of these so called replacement carbs with caution.     For the carb to operate as designed it needs the plastic floats.The Phenol[Spelling??] carb body is not plastic. Its function besides being the base and body to the carb ,is to block off the high tempeturtes from the egine.To even come close to having an after market carb work ,you have to buy a special intake manifold. Or put at least a 3/4 inch heat barrier between the substitute carb and manifold.     And remember ANY modification begets further modifications.AND EXPENSE. No other Carb works as well as a properly remanufactured Thermo quad on ourDodge  rigs.Such a total remanufacture costs generally around $500.[I just paid $535 to have mine done}.WARNING! there are very few outfits that know enough about thermo quads to even be touching them. On top of that they must have all linkage in good shape and properly adjusted .ONE such Company is SAVAS TUNING & AUTOMOTIVE In Gladstone Oregon. 503-653-5155. I am sending the contact information to the web sight "LINKS" Bob Chaney