need some help troubleshooting please

[Anonymous]

i have a dead spot that i cant get rid of when i accelerate..the dead spot isn't there if i slooowly acellerate and is fine to gun it after about 25 MPH...just got a few questions n stuff...well i have a carter YFA carb...i have the EGR blocked off with a plate..its good...everything is sealed and no vacuum leaks...but there is a small screw which i think adjusts the acellerator pump/power valve or something like that...i heard that to keep the engine from running rich when the EGR normally kicks in i could just untwist the screw which would make the shot of gas from the pump be slightly delayed so it doesnt run so rich at that spot...well i untwisted it 2 turns...i havent really paid attention to whether or not it made any difference so i'm not sure if its causing any problems...i also have my vacuum advance hooked up to full manifold vacuum...i like it..but heard that it causes a stumble...could this be my problem? i installed the MSD 2 Blaster coil today hoping that would solve a bit...but nope...runs better though...but i really hate the dead spot...especially since i cant race or anything like that...i can barely do a burnout...feels like i almost kill the car...no overwhelming smell of gas...but i do need to have the air mixture screw out quite far...any reasons why this is...does this result in richer or leaner fuel mixture at idle? i am happy with the way it runs except for the dead spot....thanks in advance

 

[Anonymous]

Dave I'll take a stab at this and suggest that your running rich. I had the same problem with a V8 and the carb was over sized. The fact that your slow take off doesn't replicate the problem was the first hint. what year is the car? There is 2 different dizzy's low vac and high vac, if yours is a low vac putting the dizzy on a high vac line could be a problem. "no over whelming smell of gas"?? You shouldn't have a welming one eather. Give the guys some more info on your setup and mods, what's your timing set at?

Steve

 

[Anonymous]

Dave, that screw you are turning at the base of the carb is the idle enrichment circuit. Backing it off only alllows more fuel at idle. It will also slightly compensate for a bad accelerator pump. Take the air cleaner off and look down in the carb while you move the throttle. You should see instant response of the accelerator pump spraying fuel into the venturi. If not, time to take it apart and replace the accelerator pump.

 

[Anonymous]

thanks for the replys...i am also pretty sure i am running rich...and the idle mixture screw needs to be out as far as it is to make it run smooth...i will check the accelerator pump...first i will adjust the screw to where it was before...if that doesnt help i will get a rebuild kit....i dont even know what kinda distributer i have...(no name blue brand, lol)...no clue what the timing is set at...i usually have it set a bit before pinging starts..seems to be where i get the best performance...i'll guess around 12-14 degrees but i really dont know. its a '74 250 but the dist is off my other '78 250. stock druaspark ignition with an MSD blaster coil..i ground out the intake where the gas enters the intake...definitely better when i did that..ummm..no emmisions stuff...yea..so i'll check out the vac advance and also play with the carb...i'll post results later..thanks guys

 

[Anonymous]

well i blocked off the vacuum advance...sorta helped the problem...but is still there a bit...not completely gone...never got a chance to open up the carb though today so that will be tomorrows little project...

 

[Anonymous]

when i took off the carb top i found a bit of metal filings n gunk...got a small magnet thing and cleaned that out...not sure if that was from before when i had the top off or not...but i pretty much got rid of the dead spot...not really noticeable...with the vac advance off i could advance the timing a bit more...the car doesnt ping but it has a slight miss at idle it sounds like...doesnt really bother me since it drives better now. anyone know how much it would cost to get a gas tank cleaned if i just brought in the car? would they need to emptey the gas and all that which would cost more? thanks in advance

 

[Anonymous]

Dave,
I had a tank, I dropped and emptied, dropped off at a radiator shop, flushed, sealed, pressure checked, and a drain plug installed for $100. Don't forget to check your sending unit filter also when you get it apart. Mine looked like was desolving and full of varnish. NorthWest Falcons has a replacement filter.

Steve

 

[Anonymous]

thanks steve...any difficulty pulling off the tank...looks like a few bolts under the car and some wires and some tubes that need unbolting, are there any little tricks that i need to know or is it pretty straight forward? thats not too bad of a price. I'm just going to drive it around for a bit, i had cleaned out the old filings with a magnet so if i take off the top of the carb next time and there is crap in there then i will take it in. thanks for the help.