MK makes a good point, it does run right once in awhile. Is the soot dry and powdery or wet and thick? When it runs do you get any smoke out the tailpipe? If so, what color? Have you redone the comp. check? Hang in there!! Sooner or later we'll hit the jackpot..... or the problem.

 

One possible cause for the low compression is the cylinders are washed down from it dumping fuel. I guess I forget all the possiblities sometimes.

 

hazbrz im haveing the same sort of problem with my '68 240 iv had it rebuilt top to bottom side to side i say its your carb the napa one you got i got it to. mine was missing parts for inside around the acclerater pump. it was junk along with the other 3 from autozone. i would look into that i hope this helps ill keep in touch. if i figure it out ill let you know

 

Have you went and physically seen that the pump is working? Just can't help wondering if Holly rebuilt this carb. Your old pump could've been bad but, the new one could be to. Last time I needed a carb I bought a rebuilt (by Holly) right out of the box the pump didn't work. Took it back and got another and it didn't work either. Took that one back and went to Ford and got yet another one (also built by Holly) and that one didn't work either. I finally rebuilt the new one myself to make it work. While I was in there I couldn't help notice the sad work they did trying to make various repairs.
Other than that how about looking in the dist. again? may have something going on when it starts to advance (maybe a wire grounding out)

 

After at least 30 years of pulling wrenches I have to say that if there is any way to avoid buying over the counter rebuit carbs do so. They are almost always JUNK! When the one on my 72 got so bad I couldn't keep it together anymore I went in to a parts store to see about buying a new one. They sold Holley remans and the sales person convinced me to try one and said they had never had a problem. The insides were like stepman said and the hot air stove fitting had a brass fitting on it with a very strange looking inverted flare with female threads. When I took it off there was only one thread left on the original so they had jammed whatever they had on there to cover it up. The external choke linkage was all wrong and the end of the reod hit the carb body only allowing the choke to close halfway. And the chokestat was junk. I basically had to rebuild their rebuilt carb.


Now here is a trick to make these things work. If you have the slider that runs up through the carb that connects to the accelerator and the metering rod then do what I did. I had fought a weak accelerator pump for years, and had tryed kitting the carb a couple times to no avail. Then I notice by design the pump rod isn't really making it's full stroke because it is a bad design and a sloppy piece of crap even if Holly never screwed it up. The simple solution was to take a short fairly weak spring and just set it on top of the accelerator/metering rod assembly and then put the top on. This forces the pump to return each time thus making a full stroke and a good squirt. I can't believe how much difference this simple fix made . I think I used a fuel filter spring out of a quadrajet and cut it in half. Now the truck has instant throttle response and the cold weather starting is much improved also.
I will say that my 68 240 does not have the same style of carb so I don't know if this trick will work on them all.
Never buy a reman, let your neighbors 8 year old rebuild yours with a rock and a railroad spike and you will have better results.
And here is another bit of trouble shooting info, leave the darn carburator alone until you are REAL sure the ignition is all in proper order. You probably will throw away a good carb and put on a POS from Napa and then you have your old problem still and now some new ones.

 

putt, the black stuff is dry on the plugs. I'll also take another look at the distributer and the vaccum adv. (its new) but i'll look closer at hte wires themselves. Someone mentioned a too much fuel pressure and some type of fuel regulator, is this something I can buy at napa? I haven't heard of one before. When I do get smoke it is white... I also noticed when i was messing with it the other day when I push gas when off it makes one good stream of fuel but when its running there is like a cloud inside carb but I cant tell if its a too much cloud or a not enough cloud.. if that sounded stupid it felt stupid as I was typing it. Ive tried to look at the fuctions so I can figure this sucker out... Thanks Again for the input, if not for you guys I think it would be on the curb with the keys in it praying for some fool to take it....

 

As I read the posts again I'm sorry to say that the carb was rebuilt by holley...I wonder if napa will balk at an exchange????

 

Oh no. Not another Holly. It sounds like it working though. What worries me now is the white smoke. That is a sign of coolant. Your not loosing any though are you?

 

Dry black is good, it means no oil, so hopefully some of this info will hit the nail. The fuel pressure regulator should be available at napa. It should be in the performance section. I had forgotten about the poor rebuilds, I always rebuild my own, so haven't had that problem. I did work at a parts store and the only rebuilt I would consider was a Tomco. The rest were basically junk like everyone else is saying. I like Holley carbs,so all this putdowns of their remans is really hurting!

 

I think Holly makes good Holly's, they just have problems when it comes to rebuilding someone elses carb.

 

I had more bad experiences with Tomco than anyone. A shop I worked at fought those guys for over a month on a feedback carb we had install on a 2.2 chrysler product. They had sent a couple and then just abandoned us and our customer with a carb that was puking gas all over inside and out. I will say that it was definately the carbs and not the tech, every carb had something different and obvious wrong.
Rebuilding a carb isn't that hard if you can follow directions. All that is usually wrong is the accelerator pump and/or dirt. If you are doing a rochester remember to change the float too. Those pheonalic(sp?) floats can absorb gas and get too heavy.

 

PUTT IM SORRY TO SAY THIS BUT IVE BOUGHT 4 TOMCOS FROM NAPA AND AUTO ZONE AND ALL 4 WHERE JUNK THEY WHERE MISSING PARTS THAT YOU CANT BUY FROM PARTS STORE AND IVE ALSO BOUGHT A "NEW" REBUILT HOLLY THAT WAS JUNK I SUGGEST TRY TO FIND YOU A FACTORY CARB. IF YOU THINK ITS YOUR CARB. JUST KEEP LOOKING YOU WILL FIND ONE I FOUNT ONE JUST TODAY FOR MY '68. THEY ARE LIKE TRYING TO FIND HENS TEETH THO.

 

Ah well, it just goes to show, if you want it done right, do it yourself. I agree that rebuilding a carb is not that difficult. HAZBRZ, I would suggest looking at another truck with the same carb to see if there is something obvious wrong. I also have had wrong float settings in the directions with the kits.

 

Sound like the timming is off or valves need to be ajusted or bad motor.
Brewster

 

just rebuild it. a 300 would be about one of the easiest things to rebuild and cheap too. all you need to do is check the condition of the bores. if they are not to scuffed just hone out the cylinders and get new rings. if you do have to get it bored , don't bire too much. get new bearings and your head redone. also check crank for worn journals and cam for flat lobes. buy a new timing set and then you set. i just built my first motor without a book. it is a 302 i built it for the strret although now it needs a cam raplacement. i got an rv cam instead of the street performance cam i wanted. other than that it runs smoothly.