390

Engine, ignition, fuel, cooling, exhaust

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JOSHR
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390

Post by JOSHR »

I need a cost efficient way to convert my 2bbrl carb and intake, to fuel injection. She's a 1972 highboy with a 390 and low geared. I'm currently looking for a trans mod, to achieve better towing speeds and I need to get efficient gas mileage while I'm at it. Any suggestions??
Lee
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Re: 390

Post by Lee »

Hi,

Well.... trying to achieve efficient gas mileage with these Highboy's is like trying to mix oil and water.

There are fuel injection kits out there but their hi-cost usually negates the purchase.

There are also a few options concerning the trans/gearing.... but again they aren't cheap.

Going to taller tires will lower RPM's at highway speeds but doesn't help with towing.

For the trans,... I went with a Ranger Torque Splitter overdrive .

Gear Vendors makes an overdrive unit. Or you could put an NV4500 5-speed, or ZF unit. Again, all of these options are $$$ and not for the faint of heart to install.

Lee
Socal F250
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Re: 390

Post by Socal F250 »

Lee, with the 27% reduction on the final drive what did that end up translating to in additional MPH.

I have a 71 F250 4x4 with the 390 and 435 and it comfortably drives about 60 before it sounds like I am wringing it's neck. I would be happy with 70 if I could get it.

I have been pondering all the other suggestions you mentioned too.

Brent
1971 F250 Explorer 4wd
2006 E350 Adventure Van 4wd
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colnago
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Re: 390

Post by colnago »

If you want decent mileage, my vote is to pull the 390 out, and swap in a 351. Sorry, not what you wanted to hear. I love my 352, but the FE is not an efficient design.

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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DuckRyder
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Re: 390

Post by DuckRyder »

Well you didn’t define “cost efficient” but there is this:

https://www.holley.com/products/fuel_sy ... el_system/

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Robert
1972 F100 Ranger XLT (445/C6/9” 3.50 Truetrac)

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Lee
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Re: 390

Post by Lee »

Socal F250 wrote:Lee, with the 27% reduction on the final drive what did that end up translating to in additional MPH.

I have a 71 F250 4x4 with the 390 and 435 and it comfortably drives about 60 before it sounds like I am wringing it's neck. I would be happy with 70 if I could get it.

I have been pondering all the other suggestions you mentioned too.

Brent
Hi Brent,

To be honest I have never checked the fuel mileage on the truck.

Running tall 36" tires and having the over-drive makes highway driving comfortable.... RPM wise.

I installed the Over-drive due to the fact that I pull a heavy Travel Trailer regularly over a 6000 ft mountain pass. The ratio spread between 3rd and 4th gear is so large on the 435 that I can't maintain speed in 4th and downshifting to 3rd ran the RPM's uncomfortably high. With the OD I shift into 3rd OD and can maintain speed with comfortable RPM.

Lee
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