idle advances when warm and off idle bog

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steveh

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issue is on mild build 340 with 650 manual choke holley. donno cam specs

I suspect issues may be related. gonna tackle the idle first...

idles fine at 700rpm when cold, but after it gets warm it jumps up to1200 or higher when I put it in park...then diseles when I turn it off.

going back through timing and air mixture adjustments today

any thoughts or recommendation before I start?
 
Throttle blades probably opened to far. Make sure when you open the choke the fast idle arm is not engaged on the throttle linkage. I would pull off the carb and look at the throttle blades on primary you should see the idle slot if it's much more than a square your throttle is open to far. Or if you don't want to pull carb off back the idle screw completely and then turn to where your linkage just starts to move then turn about a turn to turn and a half and you should be close. Initial should be good at around 15 to 20.
 
I would look into why it jumps to 1200 when warm. The run on could be caused by the high idle and you turning it off.

Does it run on if you shut it off in drive?
 
It's probably due to the high idle. Follow EL5's advice above and see if that makes a difference.

I wouldn't be surprised that once you get that under control it goes away.
 
Maybe your throttle return spring is too weak? Or your throttle cable gets hung up once you've hit the pedal? I don't know, but I would assume it's one of the two.
 
i'll start by adjusting the engine when hot, then respond back later today...thx all
 
also check vacuum going to the dist. advance. and weights for sticking inside most people forget to lube the dist shaft at the top under the rotor .
 
adjusted while hot ...idle doesn't jump over 900 in park with no run on after shut down

just gotta solve the bog now...

thx all
 
steveh said:
adjusted while hot ...idle doesn't jump over 900 in park with no run on after shut down

just gotta solve the bog now...

thx all
Click to expand...

Check pump shot. With the engine not running, look down in the carb and crack the throttle open like your going to WOT. You should see a shot of gas, as in right now, no delay.

Might check your timing for giggles if you have a light.
 
primaries only right?? it has vaccum secondaries


checking holley tune videos now to get smart
 
Yeah, when you hit that throttle you should see an instant shot.

I'm Holley dumb, so hopefully someone else can chime in on the tuning part.

I may have to learn them once I get this build done. I haven't quite decided yet as to what carb I'm going to use. I know it won't be an Eddie.

I have a '73 340 Thermoquad I'm trying to decide what to do with, sell or rebuild and use it.
 
plyed around w/ accel pump...took care of the bog...could still be a little
crisper but much better now
 
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