Tuning for non ethanol fuel

1445 Views 6 Replies 4 Participants Last post by Aaron, Jun 19, 2013

Kevin R

Discussion Starter · Jun 18, 2013

So I was getting crap in my needle and seat and I decided to fix it by installing a stainless steel fuel tank and going with PTFE lines from tank to carb. I also found a fuel station that sells non ethanol fuel.

Well after getting it all back together for some reason I have a rich condition when I tip into the mains and when I am on the mains under load. Everything else is fine. I thought it was my O2 sensor but I swapped it out and got the same reading. I went down 6 jet sizes from 76 to 70 with only about 1 point of change. Its reading about 10.5-11 when on the main according to my LM-1. Also it ran fine with the 70's and the plugs look a bit cleaner. No lean surge and ran fine.

So I borrowed a friends FAST A/F meter and will check it again and see if its my LM1 or if its really that rich from the non ethanol fuel.

Has anyone else had similar results when switching fuels? I do know or have read that when you run E85 you need to jet up to run that fuel but here in WA state they advertise that our fuel can contain up to 10% ethanol. Maybe its more than what they say.

Thanks for any input on this matter.

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Kevin R

Discussion Starter · #4 · Jun 19, 2013

Calculated Risk said:
Where is the float set?

What is the manifold vac reading at this throttle position and load? What about steady state vac reading? ( cruising down highway at 60mph constant throttle position)

What size is the HSAB?

How many E-holes? What size? What position is open and what ones are blocked?

There are several things you can do, but you need a starting point and you need the ability to adjust. First thing is to make sure the float level is at or just below the site plug hole. Then get the correct power valve based on your steady state manifold vac. Too high of a float level will help start the main circuit earlier and delay emulsion. Likewise, too high of a hg rating on the power valve will open the valve too soon.

Float level is at the bottom of plug and spills out when car is bumped. Everything else was set up by Patrick at Prosystems. I did drop one jet size from what was sent to me by Patrick.
The only thing that's weird is that the carb was tuned before (Prosystems 950hp) with my A/F meter. I had good cruise A/F along with tip in on the mains and WOT. The only thing changed was the type of fuel and the new tank and lines.

So my orig question was would switching from ethanol to non ethanol make that big of change? I guess I need to hook up the vacuum gauge and my buddies A/F meter and see whats really going on.

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Kevin R

Discussion Starter · #6 · Jun 19, 2013

66sc said:
Where do you get real gas?
This sort of sums up other posts.

There are actually lots of stations here in WA state that sell it. If you go to WWW.pure-gas.org you can find stations in your state and area.

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