hot and cold starting '89 SN

Been working on fine tuning my '89 in hopes of not having to use the throttle so much to fire up the engine. 351w - Ignition is points and carb is the 4160

When starting cold a single throttle pump before turning the key, and it fires right up but I have to keep the throttle cracked slightly for maybe 30 seconds to keep it running until it warms enough to put the throttle back into the neutral position.

For warm starts it doesn't want to fire up without a splash of gas (half blip of the throttle.)
Maybe 1 in 10 attempts it will fire with just the key. starts instantly 100% of the time if I use the throttle.

-verified timing at 10 btdc
-choke seems to be functioning properly
   (when cold approx. 1/16" gap and continues to open as as spring heats up)
-carb adjusted for max vacuum while idling forward (16 hg) (engine warm)
- curb idle around 700 rpm    600 when in gear.
- no gas dripping after shut-off
-shifts smoothly in and out of gear

not sure where to go from here, what else can I check??


also quick question regarding torque for exhaust headers :
I refreshed my headers and risers over the winter; when reinstalling I torqued to 18 ft lbs and re torqued after a heat cycle. On one side I think I can hear a faint exhaust leak developing that wasn't there initially, curious how much more I can safely tighten it?

thanks

WakeskateNW wrote: Been working on fine tuning my '89 in hopes of not having to use the throttle so much to fire up the engine. 351w - Ignition is points and carb is the 4160 When starting cold a single throttle pump before turning the key, and it fires right up but I have to keep the throttle cracked slightly for maybe 30 seconds to keep it running until it warms enough to put the throttle back into the neutral position. For warm starts it doesn't want to fire up without a splash of gas (half blip of the throttle.) Maybe 1 in 10 attempts it will fire with just the key. starts instantly 100% of the time if I use the throttle. -verified timing at 10 btdc -choke seems to be functioning properly    (when cold approx. 1/16" gap and continues to open as as spring heats up) -carb adjusted for max vacuum while idling forward (16 hg) (engine warm) - curb idle around 700 rpm    600 when in gear. - no gas dripping after shut-off -shifts smoothly in and out of gear not sure where to go from here, what else can I check?? also quick question regarding torque for exhaust headers : I refreshed my headers and risers over the winter; when reinstalling I torqued to 18 ft lbs and re torqued after a heat cycle. On one side I think I can hear a faint exhaust leak developing that wasn't there initially, curious how much more I can safely tighten it? thanks

PCM says 18 to 24 ft lbs is the torque spec for the exhaust manifold bolts.

You should probably be happy with your cold start and for the hot start issue, I'd be twiddling around with the idle mixture screws and the idle speed adjustment screw as a start.

It will be trial and error and may not meet the textbook prescribed "max vacuum in gear" when you're done

Note where they're adjusted to now so you have your baseline adjustments to fall back on if needed.

I'd be adjusting for more gas flow at idle to start with

I concur
There is no high idle with the choke, you're going to have to give it some extra throttle when cold somehow
you don't want to go too crazy tuning for cold starts and compromise everywhere else.
You're thirty seconds of extra throttle is quite on the mark and most would be extremely satisfied

Choke is very critical to the metal's ambient temperature.
that said, chock Setting 1/8" open at 75F, if quite valid
Setting 1/8" open at say 55 F, is too loose, you're going to to need some modest tension holding the plate fully closed.

Warm, does the engine truly need a 'splash of gas', or does it start just as easily with a slight crack of throttle? these details are important in the diagnostics.
Are you certain both idle circuits adjustments are effective? If one screw cannot starve the engine down, the circuit is clogged and will protest clean restarts, as well as smooth transitions

Look at that, you've mastered the fine art of "twiddling"

Good job