carb adjustments

[benno440]

Hey Guys, on my 505 with prosystems carb, I had it dyno tuned about 8 months ago and has been running well, until the last few weeks whenever I pulled up at a stop sign or whatever the engine would neally stall, so I checked the float levels and on the secondaries it was way too high so I adjusted it down to where it should be and I reset the idle, I did tinker the timing a little bit maybe one degree advanced but now when I go for a cruise and plant it it stumbles really bad, what is a simple cause for a stumble?

floats too low?
idle adjustment or timing?

 

[HEMI-ITIS]

Clean out your PM box!!


http://prosystems.websitetoolbox.com/

 

[benno440]

pro systems is basically a holley carb.

hemiitis can you send PM again please as my inbox was full.

 

[747mopar]

Is it just stumbling when you plant it or still nearly stalling? If it's when you plant it I'd check the accelerator linkage, I've had mine back off before causing a stumble.

 

[Cranky]

Carbs need attention from time to time and especially if you have to run ethanol laced fuels but hopefully, in your country, you don't have to put up with that mess. What ignition are you running and what is your initial timing? Floats would have to be really low to cause a stumble off idle. Set them according to the book. I like to see just a very little trickle at idle from the sight opening. How do the pump squirters look? Good solid stream with moderate throttle opening? Any blank spots in the squirters will cause stumbling....

 

[benno440]

Carbs need attention from time to time and especially if you have to run ethanol laced fuels but hopefully, in your country, you don't have to put up with that mess. What ignition are you running and what is your initial timing? Floats would have to be really low to cause a stumble off idle. Set them according to the book. I like to see just a very little trickle at idle from the sight opening. How do the pump squirters look? Good solid stream with moderate throttle opening? Any blank spots in the squirters will cause stumbling....

prosystems have a clear sight glass and say to have the level about 25% up the glass, i have that good., throttle linkage and squirters are perfect.
i dont know if this is anything but when float level was too high i initially turned the adjust the wrong way and fuel squirted out of the breather tubes ( i think thats what they are) before i realised i went the wrong way. Msd 6al with pro billet distributor, i believe the timing is around the 19-20 initial and 34 total,
only had this problem since changing float levels.

i sent this message last night when i was at home, i drove the charger to work today and was running okay but when i had to stop and put it in neutral the idle was at 1200 then after a second or two dropped down to 700 without me touching the pedal, then when i shut the engine off it ran on for a couple of seconds.

 

[lewtot184]

lower the float level in small increments and see if you notice a difference. make sure the boosters are not wet/damp at idle. also, large needle and seats, like .120, can be a little difficult for the float to control. look to make sure the idle air bleeds don't have any dirt around them.

 

[Cranky]

I would go after the idle air bleeds with spray carb cleaner from time to time and usually it helped. They get dirty fairly quickly driving on the street (Holley DP's). In the 80's I started having a lot of trouble with a 650 DP I used on a daily driver pickup that I was drag racing on the weekends and had to kit it several times over the course of several months. Come to find out, the station I was trading with started using ethanol laced gas and put the required stickers low on the pumps and in a hard to see place. Back then, Holley wasn't using gaskets that would stand up to ethanol fuels. I was pissed and told everyone I could about it. 6 months later the station closed. Don't know if I had anything to do with it but like to think it did lol

 

[benno440]

lower the float level in small increments and see if you notice a difference. make sure the boosters are not wet/damp at idle. also, large needle and seats, like .120, can be a little difficult for the float to control. look to make sure the idle air bleeds don't have any dirt around them.

thanks lew, the boosters did look a little damp, i will check after a run tonite, by dirt around idle air bleeds you mean as they are while installed or if any dirt if i remove them?

honestly this is just a bandaid until i can save up some more money to get a proper dyno tune, took a massive paycut in this current job cause work in this country has gone to **** at the time being.

so poor old girl doesnt get out much anymore.

 

[1wild&crazyguy]

With a new motor you will usually see an increase in idle speed as the rings seat, depending on the hone/surface finish...but none the less within the first 200 miles that levels off.
So in regards to you saying you raised the timing a hiar '1* or 2*...the idle speed would go up, not down.

now if you had junk in the bleeds, making them seem smaller,that would cause the mix to get fat or worse.


now...things to consider , and you'd be surprised...but a lot of timing chains that are billet or seem like a quality piece based on the name printed on the box...are really just total **** and stretch out=retard the cam=lower idle speed. food for thought.

Another thing...can you pull a plug or all the plugs and make sure they aren't on the edge of fouling? That can cause stumbles will give general laziness off idle and will be obvious at low speeds especially.

Sometimes a motor with a healthy amount of squeeze will need assistance from cold plugs etc to get it livable on pump gas for WOT ..BUT lower speeds take a toll cause while the plugs colder range foils a potential hot spot for pre ignition during WOT/power, it just doesnt make enough heat to clean itself off the rest of the time.