Engine performance after restart
Thread Starter
Racer
Joined: Aug 2017
Posts: 352
Likes: 47
From: Bham, Alabama
Engine performance after restart
I have a mildly built 383 with the original carburetor that has an aftermarket electric choke. I've noticed that the car runs better after it has warmed up and then I turn it off and restart. I'm trying to figure out why that happens.
Thanks
Keith
- Initial startup up, with electric choke engaged, works perfect. One WOT before cranking to set choke and then let it warm up until I need to bump the gas pedal to disengage.
- Start driving and I have a little bog off idle.
- Turn engine off and crank without touching the gas pedal. No issues
- Start driving and bog is gone.
Thanks
Keith
Race Director
Joined: May 2006
Posts: 18,731
Likes: 2,582
so the second time you get better fuel atomization since the engine is fully warmed up. Try turning both mixture screws on the Quadrajet 1/8 turn counterclockwise and see if the cold bog is gone.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
hmm,
no other changes except a restart when engine is warm and the bog is gone?
that is a head scratcher.
so, when choke is off, engine running, a bog.
only a shut off allows proper running.
so
no vacuum
residual fuel pressure
and then, ok
no other changes except a restart when engine is warm and the bog is gone?
that is a head scratcher.
so, when choke is off, engine running, a bog.
only a shut off allows proper running.
so
no vacuum
residual fuel pressure
and then, ok
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Only thing that I have is something in the vacuum system is being held open by vacuum and when you shut it down it closes....then you restart and your lean condition is remedied......
Pull the main vacuum off the carb and plug.......plug any other vacuum except the vacuum advance (Check to make sure this is functioning correctly too....no stone unturned, you are on a hunt).....and try to recreate the condition.....
Jebby
Pull the main vacuum off the carb and plug.......plug any other vacuum except the vacuum advance (Check to make sure this is functioning correctly too....no stone unturned, you are on a hunt).....and try to recreate the condition.....
Jebby
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Race Director
Joined: Mar 2017
Posts: 11,948
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From: Virginia
We shouldn't have let it get this far without asking....
OP, can you remove your air cleaner assembly, and take pictures of the top of the engine from all sides?
Perhaps it is as simple as the vac advance line being T'ed into a TVS.
OP, can you remove your air cleaner assembly, and take pictures of the top of the engine from all sides?
Perhaps it is as simple as the vac advance line being T'ed into a TVS.
Thread Starter
Racer
Joined: Aug 2017
Posts: 352
Likes: 47
From: Bham, Alabama
I'll take a look at the vacuum lines and let eveyone know. I have reduced the lines, as I upgraded the headlights to electric. The only vacuum lines I can currently think of are:
I'm planning to check my vaccum, timing and air mixture on Friday and then I can report back.
Thanks for all of the ideas and input. Head scratcher, for sure.
Keith
- Carb
- wiper door
- transmission
- vacuum advance
- brake booster
I'm planning to check my vaccum, timing and air mixture on Friday and then I can report back.
Thanks for all of the ideas and input. Head scratcher, for sure.
Keith
Thread Starter
Racer
Joined: Aug 2017
Posts: 352
Likes: 47
From: Bham, Alabama
Keith
Race Director
Joined: May 2006
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Le Mans Master
Joined: Mar 2004
Posts: 7,493
Likes: 1,502
From: Little Rock AR
I would play with the choke settings. Maybe 1 mark tighter on the choke thermo coil cap to make the choke run for a longer time while also reducing the cold RPM screw a bit so you can tolerate the raised RPM as it warms up? Worth a shot.