Base Timing curve for EFI start
 

Installed a terminator EFI with a dual sync dist to go on, looking to get some ideas for a base timing curve to start with. .030 over 455, KRE 85cc heads, 10.5:1, Voodoo 704 with Rhoads and headers. I am at 11 initial w/o vac advance but have no idea what my total is currently and at what rpm.

I'd give it 14 initial, 32 total, and have it all in around 3200-3400 to start with. That should get it running decently, and you can fine-tune from there.

Play with the initial to find where it idles best - look at the MAP reading, the lower it is the more vacuum you are making.

A chassis dyno is great to dial in the total and the "all in" point. Moving the all-in can alter the midrange power the motor makes.

Flash the ECU to an HP, it's free, and break out the laptop. That way you can dial it in by a map, and not start/total.

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I am running with 13 initial/44 cruise/34 wot. I really need to smooth it out a bit. Just haven't had a chance yet. When I leave a stop it will run at 13 until it reaches 2000 rpm then it jumps to 44 and the car really takes off because it happens all at once. It needs to be a more gradual transition. Maybe spread out over 400-500 Rpms. Other than that it seems to run fine with this program.

I run the same heads, and my setup likes 31 degrees total and wants it in pretty fast, like around 2800 rpm.

I don't currently run timing control so my initial is kind of where it is based on total advance, but my engine seemed to like 14 initial. That's a good place to start. I run 10 degrees in the vacuum advance for a total of 41 degrees at cruise. I think with those heads you can probably run a bit more advance at cruise and upper 14 to low 15:1 afr.

Thanks for the input! I plan to install this weekend and will your info.

Jason, why so lean at cruise? I think I'm at around 13:1 AFR at cruise. Even with perfect gas they say 14.7 is the most efficient combustion point.

It's what my car likes, no other reason. Downhill nearly off throttle it runs at around 30kpa on the map and right at about 15:1. Cruise ends up being anywhere between 14.4 and 15:1 depending on the load. The car likes 14.1 at idle.

With 3.73's, 26" tires and no OD, I'm getting about 16 mpg out of the thing. If I would get off my ass and convert the setup to timing control, I could probably better that by another mpg or two.

And as you take off from a start, where you get your mild ping/det, would that happen to be close to 2000 RPM? What's your cruise AFR set at? 14.7? Try dropping it to 14.2-14.4, and drop your timing to 42 at cruise, and bet it will go away.

Does it run warm at cruise?

To get a more gradual transition, you can also increase your idle timing, many usually go in the 16-18 range.

My round port 461 liked about 16-18 initial, and 32 all in by 2800/3000. I too ran 10 vacuum. But I had a little bigger of a cam, which is probably why it liked a little more initial. My mechanical was limited to 16.

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