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engine bogs down, dies
https://slantsix.org/forum/viewtopic.php?t=55242		 Page 1 of 2
Author:  DeeceDartSix [ Fri May 02, 2014 8:20 am ]
Post subject:  engine bogs down, dies
my slant has been running perfect since I've rebuilt it. I turned it on to idle the other day, and it was running perfect for about 5 minutes. Then, suddenly, it stuttered and almost died. picked up fine again, and then again almost died.

it gradually got worse and worse, and now i can hardly turn it on sometimes. when its on, it idles horribly.

ive done a multitude of tests. it has spark, the distributor is set correctly, the gear on the distributor is good, it has gas. the carb only has 25 miles on it, so im reluctant to taking it apart (even though a friend suggested the float inside is stuck. on taking out the site plug, the gas level seemed fine). Ive changed the fuel filter.

all this happened about 5 miles after i filled up with gas. ive poured 2 iso-heet dry gasses in the tank, as well as about 4 oz of marvel mystery oil. my gut tells me i filled up with some bad gas and that i should try some more dry gas.

does anyone have an idea what it could be?
Author:  Doc [ Fri May 02, 2014 8:35 am ]
Post subject: 
Need year, make model, type of carb & ignition system to start...
DD
Author:  MoreDoorVal [ Fri May 02, 2014 6:23 pm ]
Post subject: 
My 72 Valiant was doing this at low acceleration speeds, especially when there was strain on the P/S when making sharp turns at low speed, I messed with the idle speed and mixture screw and it cleared up quite a bit, I'm assuming this is something you have tried already...
Author:  63gtcv [ Fri May 02, 2014 6:33 pm ]
Post subject: 
Fuel level in bowl is dropping to low. Adjust float level. Just a thought. Sometimes with some carbs, when turning left, I think, Our cars will stumble because the fuel in the bowl will slosh to one side.
Author:  DeeceDartSix [ Fri May 02, 2014 9:55 pm ]
Post subject: 
70 dodge dart with a 4 barrel holley.

yeah, ive tried messing with the idle speed screw, fast idle cam, and idle mixture screws. nothing seems to make a difference. and like i said, i was driving it around town fine one day and the next day it started acting up, and the only thing i can think of is the gas that i bought at the end of my trip.

veeeeery strange.
Author:  ceej [ Fri May 02, 2014 10:19 pm ]
Post subject: 
OK. Well, now that you put it in perspective..

Your in experimental land. You need to pay close attention to DusterIdiot. If he tells you something, take it as gospel.

What four barrel Holley? What compression? What ignition system? What does your curve look like?

Holley is not plug and play hardware. I can help you a bit with a 390, but that's ancient history. I don't mess with Holley's anymore.

If your going to ask questions, remember, we ain't your mom. Tell us what you're really doing. We promise not to tell her. :D

CJ
Author:  MoreDoorVal [ Fri May 02, 2014 10:36 pm ]
Post subject: 
Quote:
70 dodge dart with a 4 barrel holley.

yeah, ive tried messing with the idle speed screw, fast idle cam, and idle mixture screws. nothing seems to make a difference. and like i said, i was driving it around town fine one day and the next day it started acting up, and the only thing i can think of is the gas that i bought at the end of my trip.

veeeeery strange.
Could be a vaccume leak, my PCV valve cracked and made the care idle terribly, check your major vaccume lines.

Maybe your carb needs a rebuild too? Might not fix it but it's always a good starting point if you haven't done it or know when it was last done. Haven't messed with 4 bbls yet but I'm sure it's all sort of realitive
Author:  ceej [ Fri May 02, 2014 11:17 pm ]
Post subject: 
OK.
now that you've got that input, what carb list have You got? Tell us about your primary jets, secondary jets, shooters, idle bleeds, both primary and secondary, secondary plate or jets, and bleeds for that which is applicable. Then tell us about your pump, pump cam, and which screw setting you have it on. what is the color of your pump cam?

CJ
Author:  wjajr [ Sat May 03, 2014 5:32 am ]
Post subject: 
Also if vacuum or mechanical secondary.

One way to see if you picked up a load of water laced fuel would be to pop off the primary fuel bowl, catch its contents, and look for water.
Author:  wjajr [ Sat May 03, 2014 6:01 am ]
Post subject: 
Also if vacuum or mechanical secondary.

One way to see if you picked up a load of water laced fuel would be to pop off the primary fuel bowl, catch its contents, and look for water.


Since the big crackdown on old buried leaking fuel tanks about twenty years ago, todays tanks are mostly water free. I know these tanks are checked with a stick coated with water indicator to test for water infiltration weekly or before each fuel drop. So a water problem probably is down on the list.

Where you had the carburetor off for a rebuild and it started acting up after twenty five miles I would suspect something became lose, secondary diaphragm ripped, crud is plugging idle circuit, a big vacuum leak from power brake booster if equipped, or leaking diaphragm on some other vacuum operated device.

Like CJ said, you are in experimental land:

Image
Author:  Aggressive Ted [ Sat May 03, 2014 11:13 am ]
Post subject: 
1. How much rust is in the bottom of your float bowl?
2. or fuel pump?
3. What kind of fuel pump pressure do you see on the gauge?
Author:  Aaron [ Sat May 03, 2014 11:58 am ]
Post subject:  Idle mixture screw dirty?
I had the same symptoms 2 days ago (I hit a huge pothole and things started acting up).

Holley 1920 one barrel carb. Same bog on acceleration, gradually worsening idle quality, dying at stops just prior to getting home.

Carb bolts were checked tight. Cleaned out air bleeds with carb cleaner. No change in rough 400 rpm idle.

Removed idle mixture screw, cleaned out seat with carb cleaner and compressed air, installed screw at previous 1 3/8 turns from seated.

Problem solved for now. I should take off the float bowl and see if corrosion is growing in the float bowl.

Later AARON
Author:  DeeceDartSix [ Mon May 05, 2014 3:12 pm ]
Post subject: 
went to work on it again this weekend, still couldnt figure out whats wrong. little more info on the setup:

everything is new, but OEM with the exception of the carb.
~my ignition is set up as starter relay - ballast resistor - vacuum advance distributor - BWD ignition coil

my carb is a holley 4160 with an electric choke and a vacuum secondary. its brand new from the box, never been rebuilt. when the engine was running correctly, i set the idle mixture screw back about a turn and a half. also, the fuel bowl level has always been right at the bottom of the sight plug, as instructed by the holley tuning videos on youtube.
Author:  oldskoolracer [ Mon May 05, 2014 3:59 pm ]
Post subject: 
What CFM carb is it? Any 4 barrell on an overall stock slant is gonna be a bit much. Also sounds like the ignition system should be brought up to date... Weak ignition plus waaayy too much carburetion will equate to fouling plugs in minutes, and over-all poor performance and economy...

Double check for vacuum leaks, and take a look at the plugs. Is it a 4bbl manifold or are you using or an adapter on it? Float levels (primary and seconday bowls) should be just visible through the sight glass, and mixture screws will be a shot in the dark because of the carb size and overall application... (compression, cam, ignition etc...)

Good luck buddy and let us know if you can get that carb tuned in right! Gonna take some precise tuning of the idle air bleeds, metering jets, pump cam etc...
Author:  DeeceDartSix [ Tue May 06, 2014 4:28 pm ]
Post subject: 
its a 600 CFM carb. I believe the smaller 8s used the 4160.

the engine has been bored out .030 over and i have a custom cam (the specs of which im clueless about). i cant understand how it was running so great, and then running horribly like the flick of a lightswitch.

what kind of ignition upgrades do you think i should explore? id like to hear any kind of advice i can get.
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