Timing curve for mild 360

Knebel

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Hi there,

looking for some input on how to set timing on my 360. I have a fuel injection that now also controls timing. I have played with my idle timing to get a "best" vacuum and its best at 18° initial.

I can now set:
WOT 1100 rpm 95kpa (???)
WOT 3000 rpm 95kpa (34°?)
WOT 6000 rpm 95kpa (34°?)

also "vacuum advance" aka cruise
1100rpm 45kpa (39°?)
3000rpm 45kpa (44°?)
6000rpm 45kpa (???)

anyone has advice on what to set those at?
 
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Which EFI unit are you using? Just curious. Which cam, intake, and exhaust system?

18 degrees BTDC sounds a little high for initial timing. I've used 15 degrees BTDC on my '66 383 2bbl with no problems, though. Key thing is that it starts easily at all temps with no engine "kickback". Still, if it were mine, I'd feel better with 12-15 degrees BTDC as base timing. What hot, base idle speed?

I believe that the factory distributors were set up for about 50 degrees BTDC @ 2500rpm in the "cruise" mode. Full vac advance + whatever centrifugal advance was in the distributor, OEM.

WOT timing would be about 34 degrees BTDC @ 4500 engine rpm, I believe, so the same amount at 3000rpm would probably be fine.

Key thing, to me, is when the advance starts and how quickly it builds to 3000rpm. Plus that it doesn't clatter at WOT! PLUS gets better fuel economy at cruise!

Just some thoughts,
CBODY67
 
I am using a Fitech unit. The thing with the timing is, you stab the distributor at whatever crank advance you want (10° in my case) and that will be the "base" timing. As soon as the engine runs, it goes to the set idle advance. i guess i maybe have worded this wrong, initial is 10° and idle timing is 18°

I am still playing with the idle, id lime it to idle at 900rpm but it idles pretty okay at 750-800. Just sounds smoother at 900. I do not know the cam specs unfortunately. intake is a edelbrock performer 318/360 dual plane. I also have dual exhaust..

i think the higher rpm timing for wot and cruise I got figured out, i just dont know what it should be off idle at 1100 wot and 1100rpm cruise... 25°? I believe the stock setting was 20 just off idle fur high vac cruise and 15° for wot 1100rpm. seems low to me
 
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Many of the Chrysler distributor advance curves are just getting started at 1100rpm. Maybe the spec is something like 3-5 degrees centrifugal advance at 1100rpm? Plus your initial, of course. The vacuum advance might just start to happen with ported vacuum, at that rpm.

There's a video of Nick's Garage where they put an EFI on an engine on the dyno. It lopes strongly for about an hour before the self-learning finally starts to settle it down. Takes much longer than I would have suspected.

I guess the "WOT" timing spec would equate to the old centrifugal advance spec? With "Cruise" being the "mechanical + vacuum advance" number?

CBODY67
 
okay so the settings are essentially

low rpm,middle rpm, high rpm with little throttle input (cruise...yes mechanical plus vacuum, high vacuum low engine load)

low rpm, middle rpm, high rpm full throttle (mechanical advance high load, i guess)
 
I gotta revive this for a hot minute. Sorry about that! Haha.

I have a question about timing at idle.

I have noticed, that when I get into the area where my engine is happy with the idle timing, it will be able to regulate the rpm better. I crept up from 14° in 2°setps and noticed that the rpm increase tops out at 24° maybe 25 and you can hear it from laboring idle to a smooth idle and then small stumbles. My system has a idle spark adjustment where you can add and take out timing based on fluctuating idle to make it more smooth, self controlled in the ecu.

I notice, 18° is where it slowly starts building more torque at idle up til 24 or 25°. Should I set my idle in the middle like 21 or 22° and then adjust my spark stabilizer to add and subtract a max 4 degrees to keep it stable? Meanig some torque can be taken away and some added at idle. OR do I set my timing to a point where the idle torque is at its lowest or highest? What would you do? Idle RPM is 800.

Next question, would you keep the same idle timing from idle to 1100rpm or would you have the curve increase right off idle?
 
Interesting using base timing variations to do the same thing as an Idle Air Control motor on OEM EFI systems. With those elevated base idle settings, where is the top rpm timing regulated and at what ultimate advance level? Is there a detonation limiter circuit in your system?

Increased sensitivity to off-idle throttle imput can be neat and make the car more fun to drive, IF you do not get too agressive with it. The increased off-icle power can make the car a bit tougher to drive in slippery conditions (as in rain and not just ice/snow), too, especially as the tires wear into their "more wear" rubber layer (near the wear indicators level of things). Therefore, I might suggest having the normal advance come in at 1100rpm, as most of the OEM mechanical advance curves typically do.

Just some thoughts,
CBODY67
 
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