EightStack Fuel Injection Ignition Table

[Paul Proefrock]

Does anyone have an EightStack ignition table they are willing to share?

I have my system up and running and have had the base dyno tune applied. Looking to tweak the ignition table and have some questions.

1) shouldn't the ignition timing be essentially the same as with a carbureted system? The car/motor ran well with carburetors using a 14 initial, 38 total, all in at 3000rpm.

2) looking at my new ignition table, it is "smoothed" so at 100% throttle, at 3000rpm, timing is 33.5 degrees and it doesn't reach 38 till 6000. Shouldn't it be some sort of curve between 1000 and 3000 from initial timing to 38 and then 38 all the way across from there?

My setup is an FE with EightStack and Performance Electronics ECU (hope I don't get kicked out of the forum - it's in a Roadster, not a GT40 :lipsrsealed

Thanks

Paul Proefrock

 

[Andrew Robertson]

The main thing to remember is that the timing curve in a carb engine is usually a bit compromised by the practical limitations of traditional distributor centrifugal and vacuum advance systems.

On the few EFI engines I've tuned I start by finding what the engine actually likes best at no load at various RPMs by holding throttle opening constant and finding the timing that gives best RPM. I have found that on two quite different SBCs this was 30 at idle no load ramping up quite quickly to 50 at 2500 with no load, and a steady 50 above that.

Once I have the no load timing right, I then load in a traditional wide open throttle WOT timing line (which for me was 16 at 1000 ramping to 34 by 3200). I then simply used linear interpolation between the WOT line and the no load line to build the rest of the timing table. Worked pretty good. Like you, I have always used a single timing setting above my "all-in" RPM point - 34 degrees above 3200.

I think you'd need to muck around in a very controlled dyno environment to work out what was actually optimum.

Cheers, Andrew

 

[Paul Proefrock]

Thanks Andrew, very helpful

I know this is a roadster but the setup would work very well in a GT40. EightStack and Performance Electronics is a great combination. Great old school looks, great performance and starts like a dream. and the icing on the cake, my first cruise netted me 16.5 mpg - and I haven't tweaked the ignition tables for economy :thumbsup:

Paul

 

[Dean Lampe]

That really looks fantastic!

 

[Dave Hood]

The only challenge I found with the EightStack set-up is you can't fit decent air filters on the stacks. I changed my stacks so I could use better K&N filters to protect my engine. They don't look quite as period-correct, but my I'll accept that to extend the life of my engine.