vague i know but i have lots
1st
i was here before but lost account
i have 84 f150 4x2
300 i6
tossed the stock card intake and exhaust and ignition
had instaled offi intake 4 bbl 460 carb efi exh manis 2 to 1 exhaust
switched to the old school duraspark 2 i believe is what its called
modual sits on the fender and back to older style round coil

was gettin 8 mpg at best
today switched to motorcraft 2100 2 bbl
trying to get some mpg back
well runs like crap it has full vacuum at all ports so vac advance is playing nice with me
tried to follow vacuum guides in videos to set up the air fuel
tried messing with timing

i never messed with timing before
i rotated crank till a damp papertowel popped out of # 1 plug hole
and using a wood dowel in the hole rocked the crank back n forth to determine true tdc
the rotor is pointing at # 1
i looked down after some cleaning to look for tdc on the balancer
i see nothing until about 180 away a 1/4 inch opening ...IS THIS THE MARK i dont think so i have slowly spun the dang thing several times and no other mark is present
i feel timing is close but vac advance is a bully today so i have it unhooked
and port blocked off
i need my rig its my daily driver
please offer up any help you guys can think of
im stumped

 

so i guess that large gap is the mark
i unhooked the vacuum hose for dist
re stabbed the dist after confirming tdc on compression stroke
the idle was way high
so i lowered it
and started seeing the mark
NOTE dont buy harbour frieght timing light Note
the wires and the ultra thin insulation on the cheapo 6.99 timing light were picking up more than 1 spark .... as it had slid down close to the cap
so i use a piece of foam pipe insulation to cover the lead from #1
and that help so much
again i adjusted the dist and timing back n forth they were both very high

i got the truck to about 750 rpm the motor shaking slightly
and tweaked the dist just a hair past 10 Degrees btd
and its smooth as silk
locked everything down
and went for a test drive
if i push the pedal to quick its choked out very unresponsive
but at idle siting in the drive Way i can romp it and no lag at all
i got the vacuum gauge out again and started the idle mixture screws as found on many utube vids
i can only get to 16 hg
now i am pulling off the same port as the vacuum advance was on
not manifold vacc since i have no adapter right mow to do it
another test drive same issue if i babay and i mean baby it shes fine but if i need to move in a hurry it lags down baD

 

What does it do at half throttle? I changed out the intake and exhaust manifolds like you did last summer. Like a fool I did this the day before a 250 mile trip. I had the same problem of wide open throttle bogging down, but at half it had way more get up and go. I haven't fixed mine yet, but when I get a chance I'm going to rebuild the entire carb and try running smiller jets that give me more of a mist than a stream. I believe the initial stutter in mine at least is too much fuel too fast.

Also what kind of driving do you have??? Highway or stop and go? After I swapped mine, I put a 4b holley 600 cfm single pumper on top. Driving highway I got about 15, stop and go was about 8. Depending how you drive and the type of driving, that's not that far fetched?

 

I wonder if your timing is retarded? I know you checked with the timing light, but if the harmonic balancer has shifted, that will not be accurate. Can you get a vacuum gauge and adjust the distributor for the highest vacuum? I do that on mine and then drive. If it pings under load, I retard just enough to stop the pinging. My son has a 1984 F150 with 4.9L and I have a 1986 F150 with 4.9L. His is stock and mine has been converted to Duraspark. Both pull ~21.5" Hg @ 650 RPMs. Both have 1 barrel carbs.

Have you checked for vacuum leaks?

Welcome back to the forum!

 

I'm pretty sure that large gap is NOT the timing mark.

 

What is your altitude? 16" might be pretty good if you're over 3 or 4k say. Also depends on the camshaft. An OEM camshaft will draw more vacuum than an aftermarket.

Agreed, adjust the distributor for maximum engine vacuum. At factory idle. Then back off about 1" of vacuum from that. This will get the initial timing very, very close to optimum for pump gas. May need to adjust the distributor advance internally, but this is a good way to set the initial timing if there's a question with the pointer or damper markings.

 

​​​​​​​Sounds like your accelerator pump is not working correctly.......

 

ok so the vacuum nipples were both below the bottom plate so i epoxied the one on the passenger side and drilled a hole above the lower butterfly
and bam i have ported vaccume
and as far as i can tell from top dead center the large gap is the timing mark there is no other mark on the crank pulley absolutley nothing else


i saw a great how to on setting the choke and fuel air mixit was step by step screw by screw
if anyone can post a link here id be really greatful and back to TINKERING
and driving the truck again

 

Everyone has good points but I saw in 1 post the idle was 750 RPM I think this is too high and could be kicking in mechanical advance.
Try getting it lower, as low as it will go then use the vacuum gauge to set timing.


Once timing is set use the vacuum gauge to set the idle mixture screws then recheck idle speed.


Take it out for a spin and see how it does. If you still have this bog will need to check the carb out.


Is this a new carb or used and was it rebuilt before you installed it?
Dave ----

 

BTW the 450 carb was too big should have gone with a 390 and even that could be too big for some I6 motors.
Did you try to re-jet that 450 carb?
Dave ----

 

timing mark

Small line in the middle of the white mark on the dampner

 

i know everyone keeps saying there is a mark on the damper but there just is not
the idle is just a tick above 500 now still smooth
when i set it to top dead center # 1 cyc
the large gap is the timing mark for me
i am the 3rd owner so maybe its been changed or modified

again im really looking for the tutorial on adjusting and setting up the card
and im pretty sure is a Chinese clone knock off
it said new old stock but there are no # ,s any place and my friend at a local parts house cant find any either

 

yes i did try to rejet the 450 no luck i tried finding a 390 but just not enough extra cash then i saw this 2bbl and it came on some gig blocks low rpm higher torque so i figure with the cost so cheap i could try it

 

https://www.ford-trucks.com/forums/7...ml#post6422219

i found it

 

pulling great vacuum



this is the small thin mark i scraped all the crap and old gunk off the crank at this point the rotor is pointing at #6 under the cap



this is the large gap that aligns up with tdc on compression stroke

i wonder if at some point the motor was worked on and it was setup 180 out?
is that even possible?
i have a video i cant post showing it hitting the large gap