There are lot of variables when it comes to MPG.
All I can tell you is that ignition timing is key to mileage and
performance.
Learned that as a kid working on my Mom's car.
I put on a triple carb set up and Mom always kept track of mileage.
Her only complaint was the roar noise when she had to put the pedal down to
pass.
One of key to why Patterson's distributor performance is his ignition
timing.
The EBL we sell has the best timing curve that has been developed by couple
of the GMC MH people in Oklahoma.
Those that purchase the EBL from the Manufacture lack the program we
install in ours that is for 403 or 455. Also have no clue that there is an
EBL for GMC MH.
Also ready availability of parts. The Howell based unit is mainly GM
components, so they are available from your parts store. Try that on the Fi
Tec, MSD,Sniper and others.
> I have a 78 Royale with a 403. Heavy coach. 3:70 final drive. I
> consistently get between 8 and 9 mpg on major brand (Chevron. Texaco, Petro
> Canada) gasoline usually 87 octane alcohol laced fuel.
> In years past (before alcohol laced gasoline) I used to get
> consistently 10 mpg.
> My coach has a Quadrajet and HEI ignition with no dash A/C.
> I think today's gasoline is more responsible for poor fuel economy
> than any other factor.
> Coaches that are Howell HEI/EBL equipped start and run very well.
> Vapor lock is minimized. If spark is controlled with the computer, a 1-2
> mpg improvement can be expected. But if you drive 55, you can also improve
> your fuel consumption.
> So driving habits are a factor in all this also.
> Jim Hupy
> Salem, Oregon
>
>
> > 8 MPG is pretty standard with a carb.
> > After 10,000 miles with the MSD and very accurate fuel calculations, I
> get
> > 7.666 MPG. But that is with a very heavy coach, 2 ac’s, a pod, towing a
> > tracker, with 2 bicycles off the back of the tracker. So basically a lot
> > of aerodynamic drag….
> >
> > I am not a Howell expert(Jim K is) but I’ve heard you can get up to 11
> > MPG. So what is that. About a 20% improvement in MPG? So the Howell will
> > eventually pay for its self. But how long will that take?
> >
> > As far as the plumbing on the bolt on throttle body EFI kits. The sky is
> > the limit as far as design. But there are 2 necessities on all systems.
> 1, a
> > high pressure fuel pump(either in the tank, or inline). 2, a return fuel
> > line(either to the tank or to the fuel fill neck).
> >
> > MSD, Holley, and Fitech all have detailed information on installation on
> > their websites. Someone mentioned a Accumulator tank. I believe that is a
> > option with the Fitech.
> >
> > Scott
> > --
> > Scott Nutter
> > 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21
> final
> > drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
> > installed MSD Atomic EFI
> > Houston, Texas
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--
Jim Kanomata ASE
Applied/GMC, Newark,CA
jimk
http://www.gmcrvparts.com
1-800-752-7502
