Re: IML: '67 Carter carb flat spot

[sosmi@xxxxxxxxxxx]

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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