runniny way rough!
Thread Starter
|
Freshman User
Joined: Jan 2002
Posts: 47
Likes: 0
runniny way rough!
My truck's a 76 F250 4x4 390. She's been running fine for quite a
while. Yesterday, I pulled off the carb (holly 4bbl) to clean it up
and make it pretty, also put new needles in it, a couple of new
gaskets. Nothing special. So I put it all back together today and
start her up .... hard to start, and running WAY rough. Had to pump
the gas like mad. Double checked the carb, and everything looked
ok...and plenty of gas was getting to the engine. Adjusting the carb
didn't change much of anything. It sounds like a timing problem to
me, but I didn't touch anything in that department ....so those of you
more experienced than me, what could I have messed up in the carb to
make it like that? I don't think the timing could have just gone out
just like that.
I didn't think I touched anything that'd mess it up like that
Thanks,
Tim
while. Yesterday, I pulled off the carb (holly 4bbl) to clean it up
and make it pretty, also put new needles in it, a couple of new
gaskets. Nothing special. So I put it all back together today and
start her up .... hard to start, and running WAY rough. Had to pump
the gas like mad. Double checked the carb, and everything looked
ok...and plenty of gas was getting to the engine. Adjusting the carb
didn't change much of anything. It sounds like a timing problem to
me, but I didn't touch anything in that department ....so those of you
more experienced than me, what could I have messed up in the carb to
make it like that? I don't think the timing could have just gone out
just like that.
I didn't think I touched anything that'd mess it up like that
Thanks,
Tim
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
runniny way rough!
Did you possibly put the vaccuum advance to the distributor back on the wrong carb port? Like one that has vaccuum all the time (non-ported)instead of one that has vaccum only when throttle is opened (ported).
Or how about the floats being set too high, causing fuel to overfill the bowl and run into the intake causing a flooding condition. This sounds like it is the most likely cause IMHO.
Sparky
Or how about the floats being set too high, causing fuel to overfill the bowl and run into the intake causing a flooding condition. This sounds like it is the most likely cause IMHO.
Sparky
Thread Starter
|
Freshman User
Joined: Jan 2002
Posts: 47
Likes: 0
runniny way rough!
The vaccuum advance line is at the top port, which I assume is the
right one since it's been like that for years with no problem...
however I'll try the bottom one tomorrow to see if it helps.
As for the floats, they're set fine...the fuel is just below
the sight plugs.
Thanks,
Tim
right one since it's been like that for years with no problem...
however I'll try the bottom one tomorrow to see if it helps.
As for the floats, they're set fine...the fuel is just below
the sight plugs.
Thanks,
Tim
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
runniny way rough!
Tim,
If its timing, you'd probably have backfiring.
Face the music! Get that carb back off and check it over one more time. Did you put your gaskets on backwards?
Did you over tighten your needles or bend them?
Why were you working on the carb anyways?
Did you rejet?
Good luck, Have Fun,
KingFisher
If its timing, you'd probably have backfiring.
Face the music! Get that carb back off and check it over one more time. Did you put your gaskets on backwards?
Did you over tighten your needles or bend them?
Why were you working on the carb anyways?
Did you rejet?
Good luck, Have Fun,
KingFisher
Thread Starter
|
Freshman User
Joined: Jan 2002
Posts: 47
Likes: 0
runniny way rough!
Ok, I've spent the better half of this afternoon going over the carb
again. Pulled it off, took it apart, put it back together.
Everything checked out fine... The reason I initially took it off
was just to make it shiny, but I figured while it was off I'd do
some minor work... didn't rejet, new needles and gaskets were all,
and they've now been triple-checked for correct install...I did
switch the needles to spring loaded ones ...fuel level is staying
where it should be in the bowls though.
As far as timing goes, there is backfiring through the carb when
it's running. I loosened the distributor and turned it a bit in
both directions, and it only made it run worse. The engine has a
fair bit of miles on it so it wouldn't surprise me if the timing
chain is way loose and it jumped time ... is there an easy way to
get to the chain to see how loose it is? Kind of skeptical that
it would happen just like that with no warning though...last I
ran the truck was 2 minutes to move her where I wanted in the
driveway and she was perfect
I'm really frustrated on this one ....I know I must have messed up
somewhere but I just can't figure out where!
Thanks for the input,
Tim
again. Pulled it off, took it apart, put it back together.
Everything checked out fine... The reason I initially took it off
was just to make it shiny, but I figured while it was off I'd do
some minor work... didn't rejet, new needles and gaskets were all,
and they've now been triple-checked for correct install...I did
switch the needles to spring loaded ones ...fuel level is staying
where it should be in the bowls though.
As far as timing goes, there is backfiring through the carb when
it's running. I loosened the distributor and turned it a bit in
both directions, and it only made it run worse. The engine has a
fair bit of miles on it so it wouldn't surprise me if the timing
chain is way loose and it jumped time ... is there an easy way to
get to the chain to see how loose it is? Kind of skeptical that
it would happen just like that with no warning though...last I
ran the truck was 2 minutes to move her where I wanted in the
driveway and she was perfect
I'm really frustrated on this one ....I know I must have messed up
somewhere but I just can't figure out where!
Thanks for the input,
Tim
New User
Joined: Jan 2008
Posts: 0
Likes: 24
runniny way rough!
Take the distributor cap OFF.
Now,take a breaker bar and socket to the Crank Nut.
Turn it and watch when the Rotor Turns.
Measure in you torquing about how many degrees it takes to START turning the Rotor.
This will give you an Idea How Stretched the chain is.
Dennis
Oh....Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Now,take a breaker bar and socket to the Crank Nut.
Turn it and watch when the Rotor Turns.
Measure in you torquing about how many degrees it takes to START turning the Rotor.
This will give you an Idea How Stretched the chain is.
Dennis
Oh....Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
