hi every1,
i have a 1979 f150 with a 406, head work, flat top pistons ,286h cam, wieland dual plane manifold, deck was milled, 2000 rpm stall converter, c-6 tranny, and 9 in posi rear with 3.25 gears.

problem is: i cant hook up the vac. advance without hesitation while driving. runs good at idle and at full speed, but just alittle gas and i get bad hesitation.
i have it running good with no vac. advance butlike this it has no power curve. i have installed a diff. carb and runs fine.
the carb in question is a: 4160 600cfm elec ckoke 50 state legal for a ford truck.
i have tried ajusting the mix. screws with no change.
im planning a rebuild on the carb, but was wondering if there is anything i should look for and any mods i should do while im at it



thanks for the HELP
jason

 

Is the vac advance hooked to the right vac port? Do you mean that the problem went away with a different carb? Then problem is with the carb, but it could be just where you have the vac advance connected.

Just a thought...

 

where do you have the air bleeds. 11/2 to 2 turns out should be a good starting point.do you have all the vacuum ports not in use capped. the vacuum port on the metering block on the right front is for ported vacuum. i use full manifold vacuum from the carb base plate and cap the ported vacuum at the metering block. now is this holley new or is it used. the stumble off idle could be a accelerator pump problem.

 

could also be a frozen dist. i would check that too, made a world of difference for me.

1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil

 

hi again
its in the carb!im on the right vac.. dist. is working fine.im ajusted out about 1 1/4 turns, both the same, floats are dead on.
take off is fine, high speed driving is fine, idle is fine, only have a problem during cruising,(or slight acceleration)...




thanks
jason

 

so when you are at part throttle on level ground, you get a slight skip. it also skips when you first step in from a constant cruise speed. its interesting that it skips at speed and doesnt skip at take off. has the engine popped back thru the carb or has it popped thru the exhaust pipes.i wonder if its a lean fire miss. you stated that the truck did not do this with the other carb.

 

>so when you are at part throttle on level ground, you get a
>slight skip. it also skips when you first step in from a
>constant cruise speed. its interesting that it skips at
>speed and doesnt skip at take off. has the engine popped
>back thru the carb or has it popped thru the exhaust pipes.i
>wonder if its a lean fire miss. you stated that the truck
>did not do this with the other carb.



hi again
ok did the inyard test:
moving the throttle about 1/4 open by hand i can make engine skip with the vac. advance hooked up. no skip without vac. advance
using another holley carb, i have no problems at all!
for now i have unpluged the vac. and set the timing alittle higher,it doesnt like to turn over but fires right up once it does.
1 vac goes to my pcv, 1 to the dist(bocked off at the momment) and other 1 is blocked off 2
its ok for now but i like the power curve the engine gets with the vac advance hooked up.
im pretty sure its in the carb.i know how to tune the air mix and idle but nothing other than that.
i figure if theres enough gas at full throttle then there shouldnt be a problem at part throttle
gotta be inside the carb!!! any kind of tricks i should do when rebuilding it? it a holley 4160 600cfm vacsec. sq bore elec coke
thanks
jason

 

>so when you are at part throttle on level ground, you get a
>slight skip. it also skips when you first step in from a
>constant cruise speed. its interesting that it skips at
>speed and doesnt skip at take off. has the engine popped
>back thru the carb or has it popped thru the exhaust pipes.i
>wonder if its a lean fire miss. you stated that the truck
>did not do this with the other carb.



i missed a cpl things
i have a heavy foot 0-30 as fast as i can
im in the city so it doesnt get up passed 45 some days
the carb in question is used
no popping while i've had it
1st start up after rebuild, primed engine, set crack to 13 deg
dropped in dist and fired right up
the engine seems to run its best at 26 - 28 deg.



thanks
jason

 

i have gotten away from using a timing light and have gone to timing mostly by ear. now i mention that because i will loosen the distributor and bring engine rpm up to about 2500 and advance timing until i begin to hear a slight miss. at that point i go the other direction a small amount. if the carb is used i would check the filter located at the inlet. remove the inlet fitting and there should be a small brass screen filter. finally try to not rev the engine above 2500 while the truck is in park or neutral. you might want to check out holley performance products, they have a great tech department and you can email them with questions.