Thread: E85 carb tuning
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Old 07-24-2007, 09:11 AM
Junior Member
Join Date: Sep 2005
Posts: 2
Default TIMING on E85

The anti-detonation properties of the E85 are VERY good...they can be decieving! I have a 406/AFR 227's/Super victor/13.3:1 forged bottom. I've been playing with this combo for a while to get it right and I'm almost ready to try it at the track.
On race fuel, I could run 36-38* timing, on the E85 I can advance it to 42* without a problem. That's where it gets decieving...the engine will make the most power at LESS TIMING than with the race gas! I recently talked to someone with a 434sbc on the dyno made his best HP with race fuel at 36* and made no other changes than swapping to E85. The engine responded with more HP and TQ than the race fuel at two degrees less timing (34*) and seemed more responsive. So, 2* less than race gas!
Another thing to keep in mind is that the E85 likes heat. I was running a 160* thermostat with the gas, but idling with E85 at 160* was a bit unstable ( this fuel is picky about the mixture). Changing to a 180* thermostat helped to get a cleaner/more stable idle mixture and made the throttle pedal even more crisp. I may even experiment with a 195* thermostat to see if that helps even more.
I'm currently running an AED 950 carb converted to E85 (by them-they sell 'em too) It wasn't a "bolt on" for me. I've had to do some research and change a few things to make it right-sort of trial and error style. What I've ended up with that's working for me now jet wise is 75 primary with 4.5 power valve. The PVCR's have been drilled out to .076" for additional fuel on demand. All 4 IFR's are at .043" . The secondary jets are drilled out to a .089" (not a 89 jet) and the power valve is blocked off. High speed (main) air bleeds are .038" and idle bleeds are .067". Both squirters are .042". My emulsion bleeds from top to bottom are .031", blank,.031", blank.
You can use a numbered drill bit set to measure what you have BEFORE you start changing things so that you know what your base line is before making any adjustments. This way you can always go back to the previous setting if whatever you changed was wrong.
Hope some of my trial and error will help make it easier for somebody.
tinkerin is offline