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Welll,my truck starts and runs,O.K.,with the choke closed,to 3/4 open,(when warmed-up). If I push the cable all the way to the dash,the engine dies,and doesn't start,unless choke is fully closed,even after engine is warmed-up! I've had this thing pulled apart a dozen times,adjusted the float,float drop,and the pump discharge was stuck. Accelerator pump checked O.K. I turn the air/fuel mixture screw all the way in,(engine running,)and hear no difference! Shouldn't this "kill" the engine,if the carb. was properly adjusted? I pulled the hose off of the 2-speed,while running,and it didn't seem to affect the engine,but before the H.E.I.,(Vacuum advance,it works),that type of leak would've "Killed" the engine. Hydrovac/brakes work fine.. The timing has got to be very close. It starts right up,but hesitates on hard acceleration. This is due to the fact that it'll only run with at least a 1/4 choke. May not be getting enough air.Idle won't adjust correctly,either, It can sit and idle for a half-hour,and it'll die,driving halfway around the block.Will not start-float bowl empty.this is after float adjustments,double checks. Put a new fuel pump in today,got it started,after tearing the carb. apart.(float adjustment fine,but no drop). re-adjusted and drove it right home,(2 houses),and parked it. I tried playing more with the idle adjustment,but gave up. I'm going to have to find a vacuum gauge,and timing light,and dial the HEI to the carb. I'm learning! If you're going to up-grade,you'll have to do some adjusting to make it work. I needed a timing light,and a vacuum gauge anyway. Seems like the new fuel pump helped smooth the idle out ,though. It was weak. HaHaHa!! Truck Looks Great,but now it doesn't want to show off! Maybe "He" liked the old patina better??

I will be following this one because mine is doing the same thing?

Make a check list and start with one thing at a time.
1, Timing, use the "BB" on the flywheel to set initial timing.
2, Use the vacuum gauge to set timing at idle to max vacuum, then back it off for a little drop on the vacuum guage.
3, Set idle speed to 450-500 RPM.
4, Adjust idle mixture screw for max vacuum. The choke should be completly open by now and the engine fully warm. If the engine won't idle with the choke off, adjust the idle speed up and readjust the mixture screw for max vacuum.
5, Check for vacuum leaks, check again, fix vacuum leaks. If need be, disconnect line to wiper, hydrovac and any thing else. It will idle with the vacuum advance disconnected.
6, Use a Dwell meter, to be certain the HEI is working the coil properly. For an inline 6 you should have close to 30 degrees of dwell. Tells you if the points are gapped correctly if you have points and if you have an HEI it should tell you if the HEI is getting a clean signal to the coil.
7, Verify the firing order is correct. If you have a "short" dizzy cap you need a "short" rotor. If you have a "tall" cap you need a "tall" rotor.
8, Do you have the correct base gasket under the Carb? Is there a leak at the base of the "insulator" and the manifold?
One step at a time. Fix and test one step at a time. If need be remove the HEI and go with points. You can put the Hei back if you want. Vacuum advance can leak, wiper motor can leak, Flat level can be wrong. Timing can be off. I don't have any experiance with Hydro Vac...but I would bet it can leak as well. Others will have suggestions as well. Use them and remember to do ONE thing at a time. It will get better. You might have a leak at the manifold to head, it can be tested with propane, unlight of course. These engins will run, with the timing off, plug wires in the wrong places, and with lots of things not right. They will not run real well but they will run. That is the beauty of these old critters. They actualy want to work.

That is float level...flat is good word but not for floats. I gotta get better at proof reading, just gotta.

Like Steve says, make sure the float level is OK. After that with the top off the carb , there is a tube that goes across the top of the air horn. It has a tiny plug in one end. Sometimes that plug blows out when you are cleaning with compressed air. It will cause the symptoms you mention. You can fill the end with e-poxy like JB weld.

Maybe a silly question, but when hooking up the vacuum gauge. Do you unplug the line at the dizzy and connect the gauge there?
Then do you plug the port on the dizzy?
Or do you put the gauge on the intake manifold/carb end? And should you plug that port?

Thanks.

Good question,Hogger54! I think I read somewhere to attach the vacuum gauge to the distributor advance,but I can't understand how this would work,unless vacuum is created from the oil pump?? I'm GUESSING that the gauge be connected to the line that runs from the vac. advance to the carb. base,(intake),since you'd have to adjust the air/fuel mixture screw,which is relative to that line?? THANKS,Wrenchbender Ret.! That just may be the problem! I rebuilt the carb. 2-years ago,and have had no problem,until now. Yes,the passages were blown clean with compressed air,(at the time), and maybe it took this long to work itself loose!! I'll check it out in the next day or so,and I'll be sure to let you know! THANKS,again! Steve,I already got the message about the float level! I need to proof-read,too! GREAT suggestion! My float level,and drop,were off a mile!! Even after adjustment,it doesn't want to run like it should. I'll have to check that pump discharge ball thing,too. The discharge tube was stuck,but didn't make a difference in the performance after freed-up! THANKS!!

You attach the vacuum gauge to the vacuum port on the intake manifold (the port that would go to the vacuum wiper).

What if you have electric wipers? Use the port for the 2-speed adapter? Sounds reasonable. Could I have some type of (Vacuum) blockage,that would cause these symptoms??

You want to test intake-manifold vacuum (with a vacuum gauge).

You check for vacuum at any fitting/line that runs back to the intake manifold.

O.K... I bought a vacuum gauge,and a timing light. turned it over to T.D.C.,and B.B. on flywheel lines up with the mark. So far,so good. Now here's Question One...How do you mark the flywheel(B.B. recessed to the point it's blind,within reach),and the timing mark,,without removing the starter linkage?? Sorry,I'm used to timing small-blocks,with the timing on the harmonic balancer. Easy to mark/read. Question Two...I got the engine to run,(high idle),and vacuum gauge read about 5 pounds,which put it in the "Needs valve adjustment,or vacuum leak at carburetor base,or intake manifold" category. I "advanced" the distributor,(turned clockwise),until engine started to lose R.P.M.'s,and gauge rose to about 12-pounds,but still not in the "Green Zone". I used a propane torch to check for leaks,(carb. base,intake manifold,all fittings/connections,(I stuck the torch tip in the hose that connects to the valve cover,(removed to re-adjust valves),but the R.P.M.'s stayed the same! I'm going to try the test again tomorrow,but I'm going to try it with a spray bottle filled with water. If anyone has a better suggestion/idea,I'd LOVE to rear it! I REALLY need HELP with Question One!! THANKS!!

I had that problem and found I forgot to plug the big pipe thread hole in intake.

Pull the tin cover off the bottom and expose the fly wheel. apply black paint to the "BB" and wipe it off. It will stay in the stamping. Apply white paint to the area around it for contrast. Put the tin back on, lay the timing light on the starter and you will see it just fine. A bit of paint on the pointer can help too. Set the idle at 450-500 RPM then try to set the timing. There is a mechanical advance in the dizzy, and it will add to the total advance at a "high" idle speed. If things are badly out of adjustment you may need to repeat the timing after other things are adjusted. The vacuum gauge is rated in inches of mercury not pounds by the way. Still, if you have only 12 inches of vacuum there are other issues that need attention. Any tight valve will leak enough to drop the vacuum. Any leak at the manifold will cause it to drop as well. But to get a good reading it must idle. Adjust the valves a bit loose. Add .005 to the factory spec and don't worry about the clicking. You can fix that later and it won't hurt anything but your nerves.On all of the manifolds I have seen, the fitting is on the driver side out board and below the carb insulator. Pull the line to the wipers and put the vacuum gauge on there. leave the line on the vacuum advance until it will idle.Turn the idle down as much as you can. open the choke as much as you can. If the mixture screw is in too far it will be too lean, back it out 1/2 turn and watch the vacuum gauge. If it gets better turn it out another 1/2 turn, if the idle goes up open the choke some more. If it does not, try setting the timing again. A little adjustment can make a big change at the vacuum gauge. If the idle goes up, open the choke some more and try the mixture screw again. Turn the idle down and see what you get. If all this makes no change you may have to pull the carb. You might have a loose manifold. There can be some issues with the point gap as well. One thing at a time.

Thanks for the tips,Steve! We're off!!.. I'll let y'all know how this turns out!

O.K.,this time I took the carb. Completely apart. I pulled the accelerator pump,and it was wadded up,halfway around! On a closer inspection of the vacuum line at the carb. base,the union nut was split. I took the pump discharge out again,and buffed it up good.The "BB" is stuck,though. There was some paint on the intake manifold surface where the carb. bolts to,and I cleaned that up,too. I was in the process of removing the inspection cover,when a friend stopped by. He thought the (timing) "BB" should show up in the window on the driver's side. I bumped the starter,ONCE,and,there it was!! I took a long stick,sprayed some florescent yellow paint on the end,and carefully coated the "BB",and the timing mark. I was just getting the vacuum dialed in when it ran out of gas! The (Vacuum) gauge reads "Late Timing",no matter where I turn the "Dizzy". This was at fast-idle,before engine was warmed up. I was afraid it still wouldn't idle. Does this indicate I'm off a tooth?? Maybe that's part of the reason it won't idle??

What was the highest numeric reading on the vacuum gauge, as you rotated the distributor in both directions?

12,counter-clockwise,and 14-15 clockwise. Still a ways from the "Green"

Those are low readings. I hope for 18-21.

Others will certainly provide diagnoses.

- clogged exhaust system
- leak in any part of the intake system

or, worse:
- leaking head gasket
- leaks around valves
- leaks around piston rings

Thanks,Tim! i guess that a compression test will be the next thing. I just had the head rebuilt three years ago,(with hardened seats),and the truck uses absolutely no oil,and does not smoke! I installed Fenton headers,and a complete exhaust system two years ago,and keep the stacks covered when parked. The right stack did have a wasp nest under the coffee can,until I started it after the wiring harness install. I'll check the stacks more thoroughly,too! And,I'll keep checking for more leaks! THANKS!!

If the engine has not been run in a while, you might want to tune it and run it a while.

Set the carburetor mixture to maximum vacuum at idle, then set the timing to maximum vacuum. If the idle speed increases, reset the idle speed and redo mixture and timing.

Listen for vacuum leaks. I check for vacuum leaks with a propane torch - open the propane gas until it is barely hissing. Then, carefully point the "nozzle" of the torch at all intake manifold and carburetor gaskets, fittings, and lines. If the idle picks up, you have a vacuum leak.

I did the torch test,and came up zilch-no increase in engine speed,although I found that carb. base vacuum fitting,(brass nut),split. I held the torch to it,and it didn't make a difference. The carb.base has indents for the vacuum port,and they are lined-up."I'm crossing my T's and dotting my I's on this one"! "One thing at -a time' is very good advice,and can save a guy a bunch of time and headaches! Progress is being made,but to work it into my schedule...