Tech Tip: E85 Conversion on a 4150 QFT Carburetor!

Author: Skylar Drake | 11/20/2019 < Back to Motor Life Home

There is no denying that it is easier than ever to make big power, whether that be through a rowdy mouse motor on nitrous or a junkyard LS engine with a hair dryer; it seems that anyone can make near 4-digit numbers with their home built hot rod. While we can stuff more air into the cylinders and strap on individual coil packs, there is one missing ingredient… Fuel. With today’s alcohol and gasoline offerings we find ourselves with an abundance of choices but there is one candidate quite a few crafty racers have taken advantage of. E85 fuel can be found in nearly every state and it’s hard to ignore being cheaper per gallon than even that putrid mix they call 87 Octane; this Gasohol concoction has found its way into racing series overseas and is now beginning to creep into our local venues. By containing up to 85% ethanol, it gives us the ability to crank in a few more degrees or swap a spring to “eek” out that last little bit of horsepower. This plus the cost effectiveness compared to a pail of race gas gives us an opportunity that few would like to pass up. So this time, we decide to plunge deeper into the rabbit hole of “If you can’t beat ‘em, join ‘em” by converting an RQ-1000 from Quick Fuel Technologies into an ethanol slurping treat that any Big Block would enjoy. I can guarantee that this conversion is so simple you’re going to be kicking yourself for not doing it sooner; let’s get started!
Octane (R+M)/211386-9495-97
Lower Heating Value
(BTU per Gallon)
Miles per Gallon
Relative to Gasoline
Specific Gravity
Air-Fuel Ratio (weight)914.710

Quick Fuel Technologies offers a wide range of tools to handle this E85 conversion including metering blocks, E85 testing tubes and more. We will be using their 34-106QFT kit to swap our Gasoline blocks over to Ethanol blocks (larger metering wells) which still use Gasoline Main Jets and 6/32 emulsion bleeds.

Above we can see a labeled metering block showing the different passages, it is important to install the metering block and main body gaskets on the proper side(s). Below we can see properly installed gaskets for reference.

NOTE: Because Ethanol requires at least 30% percent more fuel, you may consider using a larger pump nozzle. We had a .033 nozzle installed and upgraded to a .037 nozzle, ensure you have an Ethanol approved pump diaphragm (GFLT) as well.

QFT advises we use at least a .130 Stainless Needle/Seat (18- 10QFT), the Needle/Seat we removed was a .120 Viton Tip (notice the small black cone), Viton can have a negative reaction to Ethanol thus requiring a Stainless model. Bottom Left: Pictured is our .033 Nozzle we removed, note the Hollow Nozzle Screw that allows fuel to pass through.

We’re finished! Be sure to inspect your air bleeds for any dirt/debris and ensure our pump arm tension is correct. At WOT, our pump arm should fit a .015” feeler gauge. Reinstall any fuel lines or throttle attachments and bolt onto your intake.

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