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Excellent tips Dave. I'll try the springs
first and maybe just a bit of metering rod polishing. If I'm not mistaken,
Edelbrok still sells various sized rods that will work - in case I mess
something up. I'll let you know what happens when I get to
it.
Thanks again. (BTW, all you guys with new
Edelbrock carbs and electronic ignition are really missing out on alot of fun,
tinkering with these engineering marvels. I'm enjoying the learning
process, and personal success, of bringing this beauty back to life. To
me, that's what the hobby is all about. No doubt in my mind, the IML
community is unequaled.)
Dan Richardson
300L Family Heirloom
----- Original Message -----
Sent: Wednesday, October 17, 2007 9:04
PM
Subject: Re: IML: '67 Carter carb flat
spot
Dan, the metering rods could even be 3 step . If you check the
vacuum at the problem point ,and then above and below you would have the
range of vacuum. You could buy springs, for that vacuum
range and replace them, or just give'm the stretch. I would lean towards
the 3/8", sometimes 1/2". Try that first, by increasing the length ,
the rods pop up quicker at the same vacuum, bringing in more fuel sooner.Then
polish the last 5/8-3/4"of the rods down .002" and blend the steps to
smooth transitions. The position of the rod steps vary with vacuum, and engine
load. The tip of the rod is always in the jet, reduce the diameter of the rod,
(or up-size the jet) you increase fuel flow .Give it a try, we've
done it many times. Dave.
--------------
Original message --------------
From: "Daniel Richardson"
<TheRichardsonFamily@xxxxxxxxxxx>
Hi Dave (and gang):
That's the kind of old timer advice I knew was
out there!
It does seem lean, and I do have the accel.
pump in the max stroke hole. What am I looking for with the vacuum
test with speeds at & before stumbling? What will it tell
me?
I figured metering rods would be the next place
to attend to - I just wasn't sure how delicate they are, or if, carefully, I
can play around with them. Assuming that it's a 2 step
metering rod, at about what throttle position does each step come into
play? In other words, should I look to reduce diameter of a certain
step? Or just reduce diameter across the board?
I will try the slight spring stretching idea
first. Your guess is that because I have an original carb, it's just
running lean on today's gas? I've covered the other places to look
already?
Thanks again for the info,
Dan Richardson
300L Family Heirloom
----- Original Message -----
Sent: Wednesday, October 17, 2007
5:13 PM
Subject: Re: IML: '67 Carter carb
flat spot
Dan, you can probably solve your flat spot, or fumble by some
metering rod, and mostly spring modifications. A vacuum test at the speed
prior to, and when the stumble occurs, may be helpful. Two easy cures:
stretch the metering rod power en-richment springs, a 1/4-3/8" this will
help to en-rich the mixture sooner (higher vacuum). The other thing is
chuck-up the metering rod in your drill, and polish the steps to a more
gradual transition. You can also reduce the diameter of the rod, thus
en-richening without a jet change. Make sure the accelerator pump linkage
is in the max stroke hole too. You can't hurt much, and if the carb is
original, it's lean by todays gas quality. Ya'll have a nice day,
Dave.
--------------
Original message --------------
From:
therichardsonfamily@xxxxxxxxxxx
> Here's a question for the
carb tinkerers (hi Dave):
>
> '67 Imperial 440, w/ Carter
AFB - the model that went on HP engines w/ bigger
> secondaries.
Idles smoothly, idle screws adjusted. At WOT she goes like a
>
r__ed ape - rubber in 2nd gear with a 3:55 suregrip.
>
>
18 inches of vacuum at idle - gauge moves just like it should when I rev
the
> engine - as per the IML website (which is really neat, BTW
- everyone should
> look at that page!).
>
> Timed
at 12 degr. BTC - new chain & gears - Mallory dual point distributor
-
> mechanical advance appears to work - if I suck on the vacuum
advance, it also
> moves timing forward. Have not found a shop
with a distributor machine yet.
> Plugs are new - wires & cap
are not (I'll get them on soon) but seem to be OK.
> Again, she's
a rocket with my foot in it.
>
> I have a flat spot from
about 1/3 to 2/3 throttle. I see no black smoke during
> this
flat spot. Carb has been rebuilt (by an amatuer - me), and seems ok.
> Choke is open when warm - linkage adjusted correctly -
accelerator pump seems to
> work right - bowl vent closes just
beyond idle - VERY low exhaust restriction
> (i.e. 2 glass packs
+ small resonaters out the sides)
>
> So... the question
is - how do I fix the flat spot? Smaller metering rods
> becuse
of the open exhaust? Or is there something else I may be missing? Throw
> some old school thoughts at me to try and tweak it.
>
> Thanks, as always, for the help,
>
> Dan
Richardson
> 300L Family Heirloom
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