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Carb acting funny
https://slantsix.org/forum/viewtopic.php?t=44524		 Page 1 of 1
Author:  Ross [ Thu Apr 14, 2011 12:22 pm ]
Post subject:  Carb acting funny
Hey guys.
Havent really been on in awhile but i do have a few problems. First off is as the title states im having troubles with my carb. For some reason its acting weird. Every once in awhile when im driving slow behind someone, just after a green light and shift from 2-3, after the shift has been made and clutch is out if i give it a little more gas (after giving it some after the shift) itll do the hurky jerky for no reason. Now mind you i do know how to drive a manual ive been doing it almost every day the last half year and i can do it seemlessly. It seems to only do this when its still on high idle. Also when i give it more gas to get going faster itll fall on its face sometimes. Is the accelerator pump going out?

My other problem is i thought my collector gasket was bad, so yesterday i replaced it, it was bad but after fully tightening it up and fired it up there was still a leak, looking closer the flange on the pipe, not the manifold, is warped in the middle :shock: about a 1/16 inch gap.... i do know when i let off the gas it makes a big popping noise, my buddies truck does it too he said its cuz his has a crack in the header(his came stock with a header) so it sucks in cold air and makes that popping noise, is that true? and is that also really bad for my engine? Now that i have money to fix it up seems like im finding more and more to fix. lol

Thanks
Cody
Author:  Reed [ Thu Apr 14, 2011 12:51 pm ]
Post subject: 
Use a remflex gasket on the exhaust pipe.

The "herky-jerky"- could you explain that better? Bogging, misfiring, stalling, backfiring, etc...
Author:  wjajr [ Thu Apr 14, 2011 1:16 pm ]
Post subject: 
Quote:
accelerator pump going out?
Quite likely. Curb idle / throttle plate stop could be a little to wide causing the transition circuit to be coming on too soon as well… Hard to say just what it is without being there to drive & listen to it. If the carburetor hasn’t been serviced for a long time, it’s probably time for a rebuild.


Quote:
i do know when i let off the gas it makes a big popping noise
I doubt that the header is sucking fresh cold air, after all, that bit of plumbing is under pressure with the engine is running. What it could be is the small hole is allowing one to hear any post combustion chamber activity that normally is muffled by the muffler and directed out the back of the car instead of up front under your feet.

When a carburetored engine is throttled down from high rpm, there is always uncombusted fuel emitted to the exhaust system. If there is sufficient oxygen available in the exhaust pipe it will fire off making a popping sound. Also check your timing, if it is off it can cause fuel loading in exhaust system.

All the old cars would make a Blub-blub-blub without a hole, or a pop-pop-pop with a hole when coasting down a hill in second with foot off the gas. It was cool, if it was a Mopar, and had some miles on it, the heat riser valve would osculate between open & closed, making a neat little tinkle-tinkle in sync with the blub-blub…

Hey it’s a 50’s-60’s thing, just like lifting the frontend, and lowering the rear end was cool as well. LOL
Author:  Ross [ Thu Apr 14, 2011 3:12 pm ]
Post subject: 
Ok shift point from 2-3 is 15mph, going maybe 18 behind someone and they speed up, if i give it more gas than i already am, say maybe little throttle to 1/4 throttle or so it will kinda buck, and fall on its face, it is also running rich again, not sure why. would the bucking be caused by overfueling and not enough advance in the timing?

I put some exhaust tape stuff around it and let it sit at idle for 10 minutes like it said to let it harden. When i finally reved it there is still that little popping noise but not like somthing is exploding in the exhaust like it was. Its much more pleasant and i probably wont have as many people watching me as if its about to explode. lol I gotta go pick up my little brother from school so ill see if it sounds any different while driving. Thats when you really notice it.
Author:  wjajr [ Thu Apr 14, 2011 3:59 pm ]
Post subject: 
Like you thought, accelerator pump not making a good squirt.
[quote]Ok shift point from 2-3 is 15mph, going maybe 18 behind someone and they speed up, if i give it more gas than i already am, say maybe little throttle to 1/4 throttle or so it will kinda buck, and fall on its face[/quote]

This discription is classic poor accelerator pump performance.


When engine is not turning many rpm after leisurely up shift, and you give it part throttle, and accelerator pump is weak, there is a monetary lean condition. This lean condition will cause any or all of the following: bucking; flat spot, bog, back-fire up through carburetor; slow initial acceleration; and other annoying drivability issues.

Like I said previously, it is most likely time for a carburetor rebuild.

With the engine “Offâ€￾ remove air cleaner, look down into carburetor, operate the throttle in a way as if you were giving it ¼ throttle, and see if there is much of a pump shot squirt of fuel. Than give it a big fast throttle opening, and see if there is a lot more gas sprayed out than with the first test.
Author:  Ross [ Thu Apr 14, 2011 4:03 pm ]
Post subject: 
Ok i just got back from picking my brother up from school. Holy crap. Such a huge difference. I was driving through the neighbor hood and tried to make it buck but it wouldnt. and the popping has also gone down a little, has a lot more pep to it too and i have lots of low end power now. I just need to figure out why its still running rich. Maybe the problem was not having any back pressure. I still need to rebuild the carb though. Doubt its been rebuilt. How hard is it? Cuz the super six might have to wait till summer or longer.
Author:  Ross [ Thu Apr 14, 2011 4:18 pm ]
Post subject: 
ill try that. But right now its raining. I do have some of those symptoms though, but have improved with the sealed flange. But acceleration is still slow but a little better. The bucking and bogging. I dont dare stop on a steep hill cuz i worry it will stall out cuz it cant get enough gas. Idk how much my truck weighs. But my fastest 0-60 was 19.3 seconds. Which i thought was insanely slow. But like i said in the last post. Ill rebuild it when it gets nicer since my parents keep shooting everything i want to do down. I wanted a $500 budget for my truck cuz a have a few thousand and they said no to that idea. But its gonna need almost that much just to keep it running and getting it running better.
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