Timing
Thread Starter
Instructor
Joined: Apr 2021
Posts: 133
Likes: 5
Timing
I have a Chevy 350 with a dui distributor and I have my initial at 17 anything lower the car stumbles and anything higher the car doesn’t Liek it, so my overall at around 3k rpm is around 44 is this not normal is this way to high??
Race Director
Joined: Mar 2018
Posts: 10,712
Likes: 2,168
From: Golden Colorado
Normal dependent on many things. Forget initial, get a dial back light and check total advance “all in” at what rpm. Then go from there. Lots of good threads here on this subject, do a search. 
Thread Starter
Instructor
Joined: Apr 2021
Posts: 133
Likes: 5
-thanks so when you say check total advance you mean with vaccum plugged correct?
Race Director
Joined: Mar 2018
Posts: 10,712
Likes: 2,168
From: Golden Colorado
No, total is everything all in. Should be around 38 or so. Note RPM when it comes all in. Take this number and let it idle with advance plugged. That is initial. Then plug advance into intake vacuum and get that number. Again, do a search. Lots of good information already posted here on this subject.
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
Short answer: I'd make sure your vacuum advance is plugged into a Manifold vacuum port (full vacuum at idle, you can test with a finger or vacuum gauge). This will give you more advance at idle, which may keep your car from stumbling. Then make sure that maximum mechanical advance is limited to 36 degrees when all-in, vacuum advance disconnected and plugged.
Long answer: Email Lars for his timing papers, and follow them. Do you have a printout of the curve for the DUI distributor? All-in RPM is probably 3000 RPM or so, but it's good to check.
Long answer: Email Lars for his timing papers, and follow them. Do you have a printout of the curve for the DUI distributor? All-in RPM is probably 3000 RPM or so, but it's good to check.
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Instructor
Joined: Feb 2021
Posts: 245
Likes: 112
From: Augusta Mo
^ A correction though, total timing is normally considered without the addition of vacuum advance. So to measure total timing, vacuum advance hose is disconnected, and then rev the engine and note where mechanical advance stops.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I'm not talking about how you set timing; I'm saying that you want vacuum advance needs to be on a manifold vacuum port when you are using the car.
For setting maximum mechanical advance, you want the vacuum advance line plugged off.
For setting maximum mechanical advance, you want the vacuum advance line plugged off.
