Gas/mods
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Gas/mods
I have a 1986 f250 XLT Lariat, with a 351w and 4bbl holley racing carb. stock exhaust manifolds that run into a 2.5in true duel exhaust (without a cat) with an X pipe and a 24in thrush glasspack off each one. Running with the stock 3.55 gearing, but with 33x12.5x16in tires. And im currently pushing 6.5-7mpg. 8 if im cruising at 55mph. Any tips for increasing MPG on it? cause running 7mpg with duel 20gal fuel cells hurts.
Thanks guys
Thanks guys
FTE Legend
Joined: Nov 2015
Posts: 30,860
Likes: 4,106
From: Angier, NC
Little late but welcome to FTE
First have to ask how did you come up with the 6-8 MPG @ 55 MPH reading?
You are running 33" tall tires and I bet the speedo is off so the MPH and distance will be off too.
I would say you need to get your measurements right before you can do MPG.
Dave ----
ps: that "racing carb" cant be helping either
First have to ask how did you come up with the 6-8 MPG @ 55 MPH reading?
You are running 33" tall tires and I bet the speedo is off so the MPH and distance will be off too.
I would say you need to get your measurements right before you can do MPG.
Dave ----
ps: that "racing carb" cant be helping either
Posting Guru
Joined: Apr 2011
Posts: 1,636
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From: Orlando area
^^^^^ racing = poor gas mileage.
Seriously, the performance carbs are jetted richer, have larger accl pump shots, and the power valve opens sooner - that's what makes them perform better than the economy carbs.
Seriously, the performance carbs are jetted richer, have larger accl pump shots, and the power valve opens sooner - that's what makes them perform better than the economy carbs.
FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
You need to decide if you want power or economy - you can't have both. You didn't say what transmission you have, but a C6 auto is very poor for MPG. And a Holley carb adds to that, and especially a big one that is probably a double-pumper. Keep it if you want power, but if you want reasonable economy swap it for an Edelbrock 1406. It'll be jetted right for the 351 out of the box and you'll have better part-throttle response as well as much better MPG.
And, welcome to FTE!
And, welcome to FTE!
FTE Legend
Joined: Nov 2015
Posts: 30,860
Likes: 4,106
From: Angier, NC
Holley has an HP series carb.
The early one did not have a choke plate, shaft, etc. But guess you could add one if you wanted as the choke horn was still there.
The ones now Holley removes the choke horn for better flow so nothing to put the shaft thru.
IIRC I have 1 of each for my drag car.
Dave - - - -
The early one did not have a choke plate, shaft, etc. But guess you could add one if you wanted as the choke horn was still there.
The ones now Holley removes the choke horn for better flow so nothing to put the shaft thru.
IIRC I have 1 of each for my drag car.
Dave - - - -
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