FE ignition timing

[ZOERA-SC7XX]

What are you setting your total timing at in your FE? Give me the initial setting, the mechanical advance, and/or the vacuum advance (if you're using this feature). I ask because I'm still trying different settings in search of the optimal street settings. Thanks.

[wideglidejoe]

I'm in go kart mode, so I don't have a lot of miles on it, but my starting point is 10 initial, 38 total, all in by 3,200 rpm, no vacuum adv. I'd like to have it all in by 3,000, but if I go any lighter/smaller on my advance springs, its all in too soon, before 3,000.

Good luck!!

[FWB]

it really depends on the particular build you have, there isn't a magic number.
i personally with my build don't pay much attention to my initial, i don't have a vacuum advance though. i run 36 total for street driving with 93 octane exxon and octane supreme 130 lead additive. when i go to the track i run 38 total and 110 leaded racing fuel. i have found with several builds that the stroked big blocks run best at 38 or under, a stroked motor generally speaking is using its torque curve and not high revs to achieve performance, thus not a lot of timing. where a standard stroke might be happier at 40 total, that is if you have the fuel to keep the detonation down. you will have to experiment yourself with your motor and keep a keen ear out for pinging. read your plugs, that will tell you where the timing is right

[Excaliber]

I'm running right at 23-24 base, another 14 or so mechanical advance all in by 2600-2800 rpm or so and finally another 12 degrees of vacuum advance for a total of around 50-52.

23-24 might sound pretty high for a base setpoint but depending on your cam profile and fuel setup it's completely reasonable for a LOT of high performance engines. I'm convinced most folks don't run ENOUGH base timing and end up with "stumbling" on accelleration, or "bogging" and then spend days and dollars chasing the carb. Which often is not the problem!

Some disclaimers are in order for my setup:
1. I'm running a special after market mechanical advance limiting bushing on my MSD that is NOT available through MSD. It's a CNC'd special bushing that cost $40!! Ouch, but it's the only way to get a BIG base AND limit the TOTAL mechanical timing with a "ready to run" style MSD distributor. You don't want more than 36 to 38 total mechanical timing.

2. At light load cruise rpm a properly tuned engine can benefit from as much as 50 degrees total timing. The only way to get there is a vacuum advance. As this is somewhat controversial (running that much timing) there is virtually NO professional engine builder that would recommend it. To risky, they gotta warranty the engine or preserve their reputation. They don't trust you. They are NOT going to stick their necks out, so don't use a vacuum advance unless you know what your doing.
3. I built my engine with a compression ratio and a piston deck height, custom pistons, to specifically induce "quench" in the combustion chamber. I'm also running forged pistons. I did this so I COULD run vacuum advance, it was all thought out, including cam profile and such before I ever started on the motor. So maybe you can run vacuum, maybe you can't, depends on what and how your motor is built.

427 side oiler, iron heads, 9.6 to 1 compression. Side Oilers were NEVER designed for "quench", you have to order custom pistons to achieve that. It is way high on the list of things to do if your building an "Engine Masters Challenge" type motor and are forced to run pump gas. Quench, among other things, greatly reduces the possibility of pre-ignition. More compression, lower octane, still big horse power, it can be done!

[Eljaro]

When I had a holley 850 DP on my 427 I used to stick to 12º initial timing and 36º max. I always had runon and dieseling problems and the engine would run hot in idle.
After changing to Webers and using 20º initial timing, I have come to the conclusion that the engine needs more initial timing even if using Holleys.
Hi perfomance parts used in the engines today allow for this and it is also necessary.
I think 10º will only give you problems and no benefits, since your starter will have no problems turning your engine over and your engine will not get as hot when idling.

[Barry_R]

Eljaro is correct.

Usually dieseling (or after-running) is caused by excessive closed throttle airflow. This is when the carb idle speed setting is too high. The fix for this can be more base timing, which allows for closing the butterflies up while retaining the same actual idle speed. One really light spring in the distributor can be used to allow a lower timing setting during cranking that instantly jumps up a bit once the engine fires up.

[Keithc8]

All good points on the timing. Like mentioned it ha a ,lot to do with the amshaft and ghe engine build. Almost all FE engines will like 38 to 40 total if you have the fuel for your compression. We can run this much timing on most street egines with about 10 to 1 compression on premium pump gas. In most cases with a MSD distributor with the black bushing this will put your initial at about 16 to 18 degrees. Will normally run he light silver spring with the blue spring and this gets the timing pretty much in by 3000 rpms.
The less vacuum you have the more initial timing you may have to run to get the idle quality right like mentioned earlier.
Good luck, Keith

[wideglidejoe]

I was the first to post an answer to ZOERA's question on 6-11, I was using settings that I had used back in the late 60's/early 70's when I was messing w/FE's then. I've been away from FE's for awhile (to the dark side). I'm learning and benefitting from all of the rest of your posts!

I'm experiencing some "dieseling" occasionally, and warmer than expected temps at idle; I was second-guessing my thermostat, radiator size, electric fan turn on, etc. Now, I'm going to change the bushing in my MSD (again!), increase my initial, and adjust the carb idle speed screw to close the butterflies a little. At least I've got the right springs in the distr. But change is a good thing, I'm going in the right direction, thanks to the info from all you FE guru's!!