I've been searching the web and can't find jack outside of "remove the adjustment ports until fuel starts dribbling out." That's all well and good if the carb has some. Here's whats been happening: Great acceleration, up to 50mph, a minute or three above that and it started "bucking", nose down, (me toward the steering wheel). Also, it would die if I didn't put it in neutral and coast for a bit. A older fella at Car-quest said the float was too low and that I needed to bend the tab so it's parallel with the bottom of the top plate. So I do this, not finding any info anywhere else. It doesn't buck anymore, it surges and seems to want to die. Did I bent it too far? Am I totally off the mark as to whats causing this? Is there an actual float level that somebody knows of? The carb is on a 1977 Dodge B300 camping van with a 400ci. I really gotta get this done as it'll be hauling me, GF, minion and all the gear and stock and my trailered 66 Lark to the NYRF in a couple of very short weeks. Please help. I really don't know a lot about carbs beyond the basics.
It is highly unlikely that this problem is caused by a low float level. A low float level will show up more as a hesitation due to weak accelerator pump squirt and possibly lean idle. This sounds more like fuel starvation. Likely culprits are clogged fuel filters, weak fuel pump, or cracked/leaky suction hoses. Dodge is real bad about putting an in-line fuel filter somewhere between the tank and the fuel pump. Check it out.
I take it this is a holley 2bbl carb that was originally on truck , not holley aftermarket carb added on ? do you have a tag on carb that has numbers on it ? that should have a fuel filter maybe running vertical next to water pump - I would change that and add some good drygas/fuel treatment/cleaner to fuel ( sta-bil , seafoam etc ) . if that's the kind of vehicle that sits a lot and with today's gas quality it could only take 30 days for the gas to start getting weird on ya . is there a "gas smell" in your oil ? that should be a mechanical fuel pump ( follow your fuel line back from carb to find filter , then pump ) and sometimes if the pump diaphragm goes bad gas can seep into the oil . I've had that happen once or twice . plus - that rig is creeping up on 40 years old so anything is possible . and don't think that the older ( especially mopar ) electronic ignition systems were as dependable as todays stuff . that's worth checking also .
Make sure if it is a Holley that behind the 1" nut where the fuel line attaches that there is/is not a filter in there. Tom T.
well according to my holley info book ( HP publishing pages 80 and 191 ) and my standard/hygrade catalog - 1977 dodge truck 400 holley 2bbl should be : 2245 model carb 380 cfm calls for a 924A or 928C kit and FL9 float certain models list a CPA136 choke pulloff and a CV124 choke stat . but some models of that carb do not list those parts ? your carb numbers should be like R6737 or R6990-1 or R6990-2 or R6990 ( which is the one that calls for the choke parts ) if you search some of those carb numbers etc you may come up with more info . if you could round up one of those holley books the pics and info are pretty good . edit : yeah , just searched "holley R6990" quick and some stuff popped up . nice lookin new/reman on e-bay , $199 . new jersey . but look for your exact number if possible if ya go that route . that's a good way to check over their pics also for comparison . the fuel dribble thing is probably for the non oem holley style carbs , 4412's etc .
Thanks for the responses. I don't access the web as often as I'd like due to living in the boonies with bad reception. It's the original carb. Not sure where I'd find the numbers to identify. I replaced the inline filter before the fuel pump. Didn't find one between the pump and the carb. I did add one though because of the old gas that had been in the tank before I siphoned it out. No change. No filter in the carb behind the no.1 nut so no chance of change there.
The oil is fine. Haven't checked the distributor/ignition, but it fires right up. One short pump on the pedal after setting all night. The rest of the day I just hit the key and he starts right up.
if there was a bunch of crap in tank that could be a problem - the "sock" filter could be plugged . and just taking gas outa the tank won't fix that . one pic I saw showed the carb number on the main body of the carb , front passenger side flat surface .
There didn't "seem" to be much in there. BUT: that wasn't gas anymore, it was straight up varnish. I thought I was going to have to drop the tank to put in a new sending unit because the fuel gauge wasn't working. Now it's slowly going up. I think it's because the fresh gas is working the varnish off. Could be the sock. I hope not. Dropping a tank is a pita. AND I just topped the bloody thing off, 40 gallons. I don't have that many gas cans just lying around. LOLou:
Changed both fuel filters again. No change. Rebuilt the carb according to specs, pretty easy, it was set perfect already.:beer No change. Haven't replaced the float. But it does float, so I don't think it's that.o No: (Comments?) One friend suggested it may be the trans filter clogging and/or the return line to the gas tank. I've got 5 days to figure this out or I have to rent a truck to haul the trailer and car on it. :shock::ball: Forgot to mention: Float adjustment is printed on the back of the sheet in the rebuild kit. DOH And Holley only "Deals with performance carbs, nitrous and etc. these days." unquote". At least they directed me to a company in FL.
if its a metal float its pretty easy to tell , can hear liquid inside and it'll slosh around . but can also submerge it in a little water , look for bubbles , let it set overnite . and just because it floats does not mean it floats enough . I think those are made pretty specific for weight/gas ratio or whatever its actually called . yep - probably will not get any info from holley on OEM carbs . and you will be hard pressed to find out any info at a dealer . nobody left that old that'll remember . truthfully - if its a pretty basic lookin setup I would have looked for a decent 4 bbl intake and basic small cfm carb to put on there by now . that OEM carb may just be whipped .
It's a nitrophyll float. I don't know whether it's "whipped" or not. I checked the plates, no warp-age. It was surprisingly clean when I took it apart to clean it. Idk if I could find a 4bbl intake for this thing. It's a gas hog to begin with. The upside is that the bloody thing doesn't change mpg when it's towing.
if that is in fact a 400 ( front distributor correct ? rear dist = small block ) then the "B" blocks ( 383 400 ) use the same intake ( 440 is a "RB" block - raised block , dif manifold width ) and should not be a huge pain to find . new ones are not cheap but I do see them at swaps sometimes . you would need just a basic street dual plane low rpm intake . a 500 or 600 vac secondary holley carb or similar size edelbrock should be plenty and may actually improve mileage . and some mopar intakes are made to accept a spreadbore carb - taa-daa !! = quadrajet . they used to use the thermoquad , same mount pattern .
Idk if I want to spend the ducats on all that. At any rate, to tie off this thread: Threw on a fuel pressure gauge at the insistence of a friend. It fell flat to zero at around 50. Ergo: Clogged line/sock. Blew out the lines backwards with air pressure, (remove gas cap 1st), And it drove fine. I dropped the tank, (whee!) and cleaned it out and re-furbished the sending unit. All works great now. I hate getting outsmarted by the simple ****e.
