Garrett Fulton
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"gfulton" <gfu...@webkorner.com> wrote in message
news:41e1e031$1...@127.0.0.1...
Garrett,
Is it running rich? Cold motors like it rich, hot motors hate it. If the
mixture is set incorrectly it'll run fine when cold but start running like
buttcrack as it warms up.
Is the choke opening fully as it heats up?
Doc
The choke is opening all the way. The carb. ran fine on the 305. I'm
pretty sure this is a fuel thing, not spark, just from the way it's acting.
Garrett
If the carburetor is for a 305 cubic inch it may be running fine when cold
as the choke is on. Bit as it warms up and the choke is off the carburetor
is probably way to lean for a 400 cubic inch motor. The jetting may be your
problem.
Drive it long enough to get the motor up to temperature. Then pull the plugs
and read them. I bet their bone white, too lean. A lean condition will act
like a vacuum leak.
Brian
> If the carburetor is for a 305 cubic inch it may be running fine when cold
> as the choke is on. Bit as it warms up and the choke is off the carburetor
> is probably way to lean for a 400 cubic inch motor. The jetting may be
> your problem.
> Drive it long enough to get the motor up to temperature. Then pull the
> plugs and read them. I bet their bone white, too lean. A lean condition
> will act like a vacuum leak.
>
> Brian
Man, if he didn't rejet that badboy when it was swapped off the 305 (I'm
guessing stock Q-jet, 750 cfm but jetted WAY down for the baby 8) it's a
wonder he hasn't burnt right though a piston yet!
Doc
>
>
Yeah that's what I'm thinking, carb jetted way lean, bigger than stock cam =
runs like crap.
Brian
Thanks to everyone for the advice. I'm sure the vacuum lines are connected
right. We've set the timing at factory spec. and ran it both ways after the
problem occurred, with no change. We do have a set of jets for the Q-jet
that are one step richer. I can't start on the thing until Tues. morn. If
I get it sorted out, I'll let everyone know and thanks again for taking the
time.
Garrett
> Thanks to everyone for the advice. I'm sure the vacuum lines are
> connected
> right. We've set the timing at factory spec. and ran it both ways after
> the
> problem occurred, with no change. We do have a set of jets for the Q-jet
> that are one step richer. I can't start on the thing until Tues. morn.
> If
> I get it sorted out, I'll let everyone know and thanks again for taking
> the
> time.
>
> Garrett
Was it ever re-jetted from the original 305 configuration? If the answer is
no, yer' gunna have to go more than 1 step up bud...................
Doc
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