Stalling /
Instructor
Joined: Jul 1999
Posts: 138
Likes: 1
From: Brick New Jersey
Would you explain the need of running 110 octane. That's very extreme!! The reason I ask is, I have a situation with my L71 11:1 CR. My motor running 93 octane wants to diesel on shut down. Timing is at spec, 4* at idle. I have run AV Fuel 100 octane and clears up the dieseling on shut down. The only problem is you just can't pull into a local airport and buy AV fuel everytime you need to fill up!! Very good friend who is a seasoned high performance marine engine builder for 35 years has a feeling that when my motor was rebuilt, decked and milled she may have to much compression. Hate to have to pull the heads to check and correct compression.
Drifting
Joined: Jul 2008
Posts: 1,873
Likes: 27
From: Sonora CA
I had a somewhat similar problem with my car several months ago. Like you, I went through all the basic items first, but to no avail, kept stalling at the lights. Not every time, but only when it was idling. And like yours, it would always start right back up as if nothing was wrong. Carburetor was running too lean, readjusted the curb idle and it has never stalled since. 
Drifting
Joined: May 2012
Posts: 1,353
Likes: 44
From: Calgary Alberta
1. Timing
2. Mix too lean
Check both, starting with the timing (it is easier to rule this out as a first step than it is to rule out a fuel issue as a first step). Issues with either of these can cause the stalling you're experiencing.
Regarding timing - if your 427 is 11:1, it is possible that it will not run well at factory timing specs. You might have to advance it. I have a completely stock 1970 L46 with 11:1, and I have to keep at least 10 degrees initial timing in it for it to run properly. Lars has a good paper on timing - if you're interested.
If you move to checking fuel, use a vacuum gauge - and check all the hoses around the carburetor, as well as the torque of the carburetor mounting bolts and intake manifold bolts, for leaks.
My hunch is that your mix is much too lean.
2. Mix too lean
Check both, starting with the timing (it is easier to rule this out as a first step than it is to rule out a fuel issue as a first step). Issues with either of these can cause the stalling you're experiencing.
Regarding timing - if your 427 is 11:1, it is possible that it will not run well at factory timing specs. You might have to advance it. I have a completely stock 1970 L46 with 11:1, and I have to keep at least 10 degrees initial timing in it for it to run properly. Lars has a good paper on timing - if you're interested.
If you move to checking fuel, use a vacuum gauge - and check all the hoses around the carburetor, as well as the torque of the carburetor mounting bolts and intake manifold bolts, for leaks.
My hunch is that your mix is much too lean.
Last edited by Brcmpbl; May 2, 2015 at 02:38 PM.
Thread Starter
Le Mans Master
Joined: Nov 2001
Posts: 8,839
Likes: 1,960
From: LONG ISLAND
2025 C3 ('68-'73) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
I know that Hei ignitions modules going out cause symptoms as you described but I'm not sure if points would do that if they were not working properly. I'm just not sure you have a fuel problem with it being intermittent. Fuel usually will keep the problem around all the time and ignition can play games by working and not working. Just my thoughts so I hope you get it fixed.
Thread Starter
Le Mans Master
Joined: Nov 2001
Posts: 8,839
Likes: 1,960
From: LONG ISLAND
2025 C3 ('68-'73) of the Year Finalist - Unmodified
2024 C3 of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
I had a somewhat similar problem with my car several months ago. Like you, I went through all the basic items first, but to no avail, kept stalling at the lights. Not every time, but only when it was idling. And like yours, it would always start right back up as if nothing was wrong. Carburetor was running too lean, readjusted the curb idle and it has never stalled since.
Drifting
Joined: May 2012
Posts: 1,353
Likes: 44
From: Calgary Alberta
This is what was happening with my L46 - with the choke on when cold, or under normal driving conditions, the car was fine, but it couldn't maintain an unassisted idle. It was too lean, and the culprit was a leak at the manifold. I torqued down the manifold, and the car ran as close to fine as a 45 year old original engine can.
But, ignition is a good thing to rule out first - takes only a couple of minutes to check timing.
Last edited by Brcmpbl; May 6, 2015 at 10:26 PM.
