I've been trying to figure out this problem with my girl's '63 Nova for a long while now... It starts fine, idles fine, but it just dies when you try to take off. It acts like a bad vacuum leak, but I've replace all the vacuum lines, checked the advance, sprayed all over with carb cleaner listening for a rise in RPM... Still can't figure it out. My only last two ideas are either a carb issue (it has a reman from OReilys that I've opened up, checked, cleaned, etc.) maybe wrong size? There are no part numbers on the carb to check for application... Or I've heard from a few others that the manifold gasket is a common cause for this issue. Any thoughts on this are greatly appreciated!! Maybe some input will spark that "ah ha!" moment... I'm at wits end with this thing.
possibly the accelerator pump in the carb is not giving enough fuel.With engine off,look down the carb,move the linkage.You should see a strong flow of fuel
Well, if it idles fine then it's not going to be a vacuum leak. Like others have said, accelerator pump in the carb.
Give it a quick test with vac line to advance off and plugged...a funny trouble spot on these is the offset pivot point where breaker plate moves for vac advance. It wears out and allows the breaker point to shift over under advance conditions ro where the points are fubar. Will idle fine, dropds dead at certain advance range...
As already mentioned, it sounds like a weak or delayed accelerator pump. Also check ignition wiring, especially where it p***es thru the distributor to the points. Broken down wiring or terminals can act up when the vacuum advance plate moves. And check the distributor for excessive side-to-side shaft movement. The Chevy inline sixes were notorious for this.
Watching a dwell meter and the damper with a timing light while revving in neutral with vac line plugged, and unplugged can answer a lot of questions. steady, correct dwell (+/- 1 degree) and idle timing, and a smooth sweep of increasing ignition advance when revved with vac disconnected are pretty much necessities
On those 1BBL carbs, make sure the top and middle sections are tight. I've seen many of them loose before. Bob
Forgot all about that issue! On the older model carbs I thought they loosened up between the throttle body and the bowl. Couple of big ol' phillips head screws if I remember correctly.
That's one thing to look for, grab the air horn and give it a twist to see if the body is loose from the throttle body. I bought a car cheap because of that once. I'm with the others though in that my bet is on the accelerator pump. Carb kits for those are under 20 bucks and they aren't hard to rebuild.
In addition to all of the carburetor issues mentioned (accelerator pump and loose screws), check to make sure the vacuum advance and mechanical advance in the distributor are working correctly. On my 230 (from my Nova) that I had in my 50 truck I had a bad bog when accelerating and the vacuum advance was bad.
Is the car an auto or stick? If all the above suggestions fail and it's an auto, it could possibly be in the trans. It happened in my '63 Pontiac Grand Prix with a "Slim Jim". The problem was sudden and I had to start the car, neutral drop it into gear when taking off, the drop it into neutral when I had to stop. Pulled the trans and all the ears on the clutches had broken off. Swapped to a 350th because it would cost more to fix the "Slim Jim" then to do the swap.
It may also be debis of sorts stuck in one of the holes in the emulsifying tube between the main jet and discharge tube. I had alot of trouble with this on my early Falcons. JW
chev 235 and 250 were all known for intake bolt backing out wont cause a problem at idle check carb base carb for looseness another common prob with chevy 6 is the dist bushing bad will act sameway hope this helps tom
Probally idleing off the transition slots. Try backing off the idle speed screw and adjust the mixture screws to get the idle speed back up. Keep doing this until it will idle with the least throttle opening.
Make sure that the distributor shaft and bushings aren't excessively worn. I remember several Chevy sixes that ran erratically due to the shaft flopping around so much that the point gap varied.
Check to see if the vacuum advance is hooked to ported or manifold vacuum. If it is hooked to manifold vacuum and then the timing is set to the usual couple of degrees, as soon as you tip into the throttle the ignition timing goes to **** and the engine bogs. If you are using manifold vacuum, set your initial timing with that line disconnected and plugged.
Thanks for all the advice everybody!!! So the accelerator pump definitely is lacking. Instead of steady stream, it only lets out a few drips... I took the carb apart, blew out all the p***ages, new gaskets, etc. The old accelertor pump looked brand new! I put the carb back together and it still does the same thing, only a few drips instead of a steady stream... The carb is a reman from O'Rielys.
I wonder if the accelerator pump check ball was left out. Without it, fuel would just get pushed back into the float bowl instead of up the p***age and out the squirter.
A possibility... the diagram from a carb rebuild kit shows where it should be. The trick is to find one without buying a whole kit, or take the carb back if its still under warranty. I would do a general fuel pump volume check just for the heck of it to rule out a fuel supply issue. Bob
I haven't got a chance to really mess with it in a while, but I need to so she'll have better luck selling the dang thing... I checked the distributor over again, advance unit seems to work like it should from what I can tell, but I'll throw my vacuum pump on it to see for sure. I did notice, however, that the shaft is a little wobbly... You can rock the whole dist. back and forth a little, maybe a few thousandths, even though the clamp is tight (rock as in forward-backward, not rotating it...) I'm ***uming this is a big part of the issue?
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