Surging at low rpm

[124JOE]

mine has a eletric shutoff valve there

[majicwrench]

GOOD! Is the valve clicking when you hook/unhook power?? And guess what, behind that valve is the jet!

[dmwhiteoak]

Thanks Magic, I didn't see that one. I have rebuilt carbs on Hollys, tractors ,mules and 4 wheelers. maybe I can do this one.I appreciate all the help from you guys . I will let yall know how it works out. I am so ready to get this car running the way it was designed too.
Dennis

[124JOE]

while doing a rebulid on my carb i used a 9v batt to test that valve
click itty click click.joe

[dmwhiteoak]

After tearing down the carb to install new parts in the kit I found my problem. The float body is warped. It appears someone put too much tourque on the four bolts to the manifold, at least thats what it looks like. I think I will try and shave off enough to get it back true. If that does not work I guess I'll be in search of another float body or carberator.Any suggestions?
Dennis

[124JOE]

I have been working on this car for a month and now I'm at the carburetor. At low rpm(below 3000) , it surges pretty bad.
I don't know which carburetor it is, but it has two set screws on the left side. One is for idle adjustment and one for fuel /air mixture. It seems to run better with fuel/air mixture screw out quiet a ways. I was wondering if there was a base line to start at like maybe two turns out or something. Maybe this not the problem, I don't know. Maybe someone has had this problem before. This appears to be my last obsticle. It does have a new crane electronic ignition that was installed by the previous owner. This could possibly be the problem. Anyone have any ideas?

Thanks Dennis

ok we need to know what year it is
as to track down the carb #
79 has a 28/32 adha
my 78 has a 32/32 adfa
these #s refur to the size of the butterflys /venturies and manifold
on the 79 the first 28mm is the primarys and the 32 is the secondarys


if shes boging it probaly needs a tuneup
if thats not curing it then the timing might have iusses.joe

[dmwhiteoak]

Joe, The car is a 78 spider. The # on the carb is 32adfa 11 102. It has new plugs, new wires and a new crane fireball 2000 electronic ignition sys. I have checked compression dry and wet. All seems good there. It does have a noticabe miss but I just assumed it was in the carb.When I try and set the timing the time mark is all over the place. If I try and get it close it runs like crap with no power. When I advance it it runs well execpt for the surging. you cannot feel the miss while driving as you can in a v8. This is my first 4 cyl. So I am still learning as I go. My brake booster hisses while running until you mash the brake and then the car will idle upand stop hissing. I plugged off the vac nipple to the booster but that also did not cure the surge.why would the booster hiss? The vac line to it does not leak. is this an internal booster problem? Dennis

[124JOE]

yes theres a intenal diaphram,they ware out

my hanynes manal says to set the timming by ear "untill it runs best"
then set the carb

the fourm guys say get the light out and set it to 0 tdc
and others say 10
i say pick the way it runs the smoothest.joe

[dmwhiteoak]

Last night I put the carburater back on after sanding the warp of the bottom of the float body.I now believe if a vacuum leak is my proglem it is coming from elsewhere.Maybe the intake gasket.Before I replace that I will return to the firing and recheck wires and distributor. I just assume the wires are new as the look to be in good shape and look new. I checked all clips and a solid contact to the wire conductor is made on all wires.The P O never had it running after he installed the ignition sys. so I have nothing ther to go by. Any thoughts? I checked the cap and no cracks , no shorts in wiring. Im just about ready to take it to a local Fiat mech but just can't stomach the thought that I have been defeated.Im not in a bind for it other than Im ready to enjoy some of my travels.I will consider any and all suggestions on why I can't get the surge GONE. Thanks Dennis

[majicwrench]

Intake vacuum leak not likely. Can you adjust the idle mix screw and change the idle?? If you slowly rest your hand over the carb while idling does idle improve??

[dmwhiteoak]

Magic, The idle mix screw seems to have no effect as of the last time I tried it. If you gently place your hand over top of carb it does idle up and smoothes out. I just assumed I was doing the same as choking the carb but taking air off the top would probley allow fuel to mix with vacuum leak and smoothe it out. thats what I have been thinking but what about the miss in motor ? Your thoughts?

[dmwhiteoak]

The idle mix screw will make it run worse and kill the motor but will not smoothe it out anymore than what it is. I now have it 2 1/2 turns out from seat.

[majicwrench]

If idle still improves with hand over carb, it is too lean. Usually because idle circuit plugged. Any vacuum leak bit enough to make a diff would be big enough to hear. Get a hunk of vacuum hose and listen around.
If you look down carb (glasses on, right) is there any fuel dribbling out of venturis at idle?? At idle you should not be able to see any fuel while looking down throat of carb.
Does it actually miss?? Or is it just the idle rough??

[dmwhiteoak]

You can see fuel dribbling out at idle. I see that all the time while working on it.Although if you increase idle speed you no longer see it ,(at least i dont without my glasses because I can't see up close with them).I have boiled out carb, soaked in chem-dip and sprayed carb cleaner in every hole and jet possible.I"ve never owned a 4 cyl before but standing ,idled up any at all it sounds like a miss would in a v8 at idle.would a miss in a 4cyl feel like a surge? I dont believe idle circuit is plugged unless its not what Im thinking about. I unscrewerd the elec thing someone said the idle/low speed jet was and washed out well several times . No change.

[majicwrench]

If it is dribbling/spitting out of venturies there is something wrong. USUALLY this is because the throttle plate is too far open, creating enough air flow to suck fuel out of venturies. Back off the idle speed screw. USUALLY the idle speed screw has been turned up too far because the idle mix system is plugged.

So, does the soleniod click when powered/unpowered?? YOu may want to pull the soleniod, energize it, and clean it again. It does little good to clean without it energized!
What is idle speed?? Can you simply turn out the idle speed screw and lower the idle??