E85 jetting for IDA 51,5. Anyone with suggestions?

[Speed-demon]

I have upped my comp to approx 12,5 and have started dynoing my engine today. We have experienced some problems, as the engine is going very lean at full throttle (lambda 1). We have tried up to 240 mains and 170 airs.  80 idle jets. The spec is 94x84, 12,5:1 compression, Street Eliminator heads (flowing approx 190 cfm), JPM cam. 42 mm venturies, F11 emulsion tubes,  ignition set to 32 degrees. The engine already makes 164 hp  at 6300, so the power looks promising. We have not tried to pull it further because of the lean condition. The needle jets are 300s by the way.

Any suggestions to jetting, timing and emulsion tubes?

[Erlend / bug66]

Where did you start? 30% over last years jetting?

You can stop there, so we have the same power

[fish]

I would be more inclined to increase the jetting by 40% and may have to play with accelerator pump adjustment
How many progression holes?
250 main
160 air
Try F2 emulsion tubes

Good luck, you getting good HP already

[kb]

Seing that E85 requires 30-35% more fuel, are you emptying the chambers of fuel perhaps? I guess a 300 needle valve should be more than enough, just a thought..
I can't really imagine an engine with those specs should need 240 main on E85..?

Here's something to remember also, from John @ Aircooled.net:

If you need 35% more fuel, that's 1.35 multiplier. But jet area is the SQUARE of diameter, so you need to multiply by 1.16.

If you use the "thumb rule" to use 4.1-4.3x venturi size for main jet on petrol, that should equal to 175 main jets. That multiplied by 1.16 is roughly a 205 main jet.
(I'm no expert, just throwing out what I've read. I haven't finished my E85 conversion yet..)

[stretch]

I couldn't get E85 to work on carbs.  I think I had a problem with moisture ingress.  The fuel if left for a few days would turn to jelly in the float bowls, jets, etc.  Turned into a nightmare to get the carbs clean.  I switched back to super unleaded after.  Shame as the car ran really well on E85.

[Fiatdude]

I couldn't get E85 to work on carbs.  I think I had a problem with moisture ingress.  The fuel if left for a few days would turn to jelly in the float bowls, jets, etc.  Turned into a nightmare to get the carbs clean.  I switched back to super unleaded after.  Shame as the car ran really well on E85.

E85 can't be left in the car for any period of time -- It caused rusting of my oval's gas tank ABOVE the fuel level -- --

It has to be treated as pure alcohol, with the carbs and complete system being flushed with 100% gas after each use, especially if the car is going to sit for more than a day or two -- or it will really mess up all of the parts in the fuel delivery system and carbs

[stretch]

I couldn't get E85 to work on carbs.  I think I had a problem with moisture ingress.  The fuel if left for a few days would turn to jelly in the float bowls, jets, etc.  Turned into a nightmare to get the carbs clean.  I switched back to super unleaded after.  Shame as the car ran really well on E85.

E85 can't be left in the car for any period of time -- It caused rusting of my oval's gas tank ABOVE the fuel level -- --

It has to be treated as pure alcohol, with the carbs and complete system being flushed with 100% gas after each use, especially if the car is going to sit for more than a day or two -- or it will really mess up all of the parts in the fuel delivery system and carbs

That's what I found out (the hard way), I suppose if it's a race car it's not too bad, but, for a street car it's too much of a pain in the ass.

You can't buy it from the pump here anymore anyway.  (Not that i'm aware of).

[Speed-demon]

Finished on the dyno today. 182 hp at 6500, which was disappointing, as the engine delivered 197hp at 7200 last year. Same combo with the exeption of the head chambers, lower comp 10,5:1 and pump gas last year. Had hoped for 210hp today.... It is dynoed by Erik Dahlberg (Jee) dyno, which is known to be at the consrvative side.

We ended with 250 mains, f7 emilsion tubes, 170 air and 80 idle. 30 degrees advance on the ignotion (surprising, i thought it would like a lot more on e85 than on pump gas).

Took a leak down after we finished, and found 10% leak at cylinder 2 and 4. That should explain some of the poor performance. But how much?

[Erlend / bug66]

You could try to dyno it on 98 octane?

I can understand the disappointment. How did the lambda end up?