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Joined: Dec 2010
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I have kept my 1979 F-250 4x4 in barn for many years and its a gas guzzler. Anyone ever done a conversion to a 12 valve Cummins. Mine is still a nice truck and still would rather drive it than my 19 f350 but just uses to much fuel. Wondering what I could expect on fuel mileage. Mine has 3:54 gears auto trans.
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Joined: Apr 2010
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Campfire Outfitter
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Campfire Outfitter
Joined: Apr 2010
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There is a poster here that did a Cummins swap into a 79 Crew cab. It was sweet and he had a good thread you can search for but I believe he sold it a while back. Good luck
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Joined: Sep 2014
Posts: 21,734
Campfire Ranger
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Campfire Ranger
Joined: Sep 2014
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$4k for an engine. $1k+ to swap?
10mpg to 20mpg.
10,000miles
1000gal gas x$2.80= $2800 500 gal dsl x $3.40 = $1700
So, you might recover $1100 per 10k miles.
40 or 50k miles to break even. Bet you won't drive that in decades if it's a barn dweller. Plus, if it now get 12 or 14 mpg, your payoff just got worse.
I love the torque and performance of a Cummins12v, many who are used to gas engines don't like the turbo lag, and high torque/low horsepower profile.
Always hearing how Chevy or Ford diesels are better, just because they are more like what car drivers are used to.
Parents who say they have good kids..Usually don't!
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Joined: Dec 2010
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Thanks Kid, will see if I can find his thread.
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Joined: Apr 2010
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Campfire Outfitter
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Campfire Outfitter
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Is your 79 a V8 or I6? If perchance it’s a 6 cylinder you could put a 4BT Cummins in it relatively easily if you could find an old Frito Lay truck or UPS truck with one in it. They were about the same power as the 300 six but can be easily turned up and they last forever and make decent mileage.
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Joined: Sep 2014
Posts: 21,734
Campfire Ranger
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Campfire Ranger
Joined: Sep 2014
Posts: 21,734 |
Acesneights had the cummins/Ford.
You should pm him. I think he liked the result, but Igor the impression he wouldn't do another.
And his was an awesome truck.
Parents who say they have good kids..Usually don't!
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Joined: Aug 2010
Posts: 27,782
Campfire Ranger
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Campfire Ranger
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It’s pretty pricey unless you are very resourceful and handy. My neighbor got one of a school bus and I think has the motor now in its second or third home . May wanna Check bolt pattern on your Ford drivetrain.
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Joined: Dec 2010
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Mine is a V8 351m with c6 auto that I have found is not a good choice of trans for fuel economy. I will most likely put truck in my shop and do the engine swap just need to visit with someone who has done it to hopefully eliminate some mistakes along the way.
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Joined: Apr 2010
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Campfire Outfitter
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Campfire Outfitter
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I’d talk to Tim Meyer about building a good 400 using his parts in your block and heads. Properly tuned you can see 14mpg with the C6 and reasonable sized tires. Plus all of your mounts and accessories are there, no junkyard searching or fabricobbling stuff up. Tim is the only place making good parts specific to the M blocks and really knows those engines.
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Joined: Dec 2010
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14mpg would be almost double what its getting now. Its gets 9 on highway and 8 just running around.
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Joined: Dec 2010
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Thanks cwh2. I remember the sale thread now. The build tread answered some of my questions already.
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Joined: Jan 2008
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Campfire Ranger
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Campfire Ranger
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I wouldn't do it again, but it was fun.
Shoot me a pm if you have more questions.
Glad to help out.
Screw you! I'm voting for Trump again!
Ecc 10:2 The heart of the wise inclines to the right, but that of a fool to the 24HCF.
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Joined: Dec 2010
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Will do after the holiday weekend.
Thanks
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Campfire Tracker
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Campfire Tracker
Joined: Sep 2007
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Considering something similar myself, a friend replaced a 460 with a 12 valve in a 92 with the OEM 5 spd, he gets 23 mpg @ 70 mph. I have a 90 Cummins with Dana axles, only drawback is the original 3 spd auto.
Eagles may soar, but a weasel never got sucked into a jet turbine!
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Posts: 764
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I have seen MANY 76-79 F 250s both stick and auto and have NEVER seen one get anywhere near 14 MPG no matter what was done to them or which engine combo was used, mine got 11 with headers, a good intake, carb and cam designed for economy, that was IF I didn't get it over 65 on a flat road, a 12 valve would definitely get you there and likely into the 20s but a lot of work it would be!
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Campfire Outfitter
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My buddy’s son had a mid 90s Powerstroke. They bought a school bus with a Cummins and had it swapped. Their money, so who am I to judge. Can’t see how it penciled out.
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Joined: Jul 2004
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Campfire Tracker
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Campfire Tracker
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You tube it. Couple of good ones there.
If you find yourself in a hole....quit digging
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Joined: Apr 2004
Posts: 42,695
Campfire 'Bwana
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Campfire 'Bwana
Joined: Apr 2004
Posts: 42,695 |
I think Higbean did that conversion also....... Local guy I run into here once in a while around town, has a 74 or 75 F 250 4 WD,,,,
his sons, own a diesel repair business in town...
they had one of those IVECo's trucks brought into the shop that had been totalled, the customer just let the vehicle go..
when Dad's old 390 finally went with 300K plus on it, they pulled the IVECO engine out and trans and put it in the F 250...
He's got alike a 50 gallon after market tank on the F 250 due to the old 390 camper special....
he ran the vehicle up to Bellingham WA to visit his brother and made it all the way back to Roseburg before he had to fill it up.....worked out he was running 24 mpg or so on it.. and that is what he still gets with it....
due to the age of his truck and where he lives in Oregon ( no EPA inspection), it doesn't have the DEF crap on it... Lewss HO over the 390 4 Barrel, but it makes up for it in torque....
I think that IVECO engine is a 6, but I really don't remember, as the last time I saw one its been quite a while...the vehicles are certainly around enough.... commercial vehicles.
"Minus the killings, Washington has one of the lowest crime rates in the Country" Marion Barry, Mayor of Wash DC
“Owning guns is not a right. If it were a right, it would be in the Constitution.” ~Alexandria Ocasio Cortez
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Joined: Apr 2004
Posts: 42,695
Campfire 'Bwana
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Campfire 'Bwana
Joined: Apr 2004
Posts: 42,695 |
I wouldn't do it again, but it was fun.
Shoot me a pm if you have more questions.
Glad to help out. saw this after I posted, sorry Higster...
"Minus the killings, Washington has one of the lowest crime rates in the Country" Marion Barry, Mayor of Wash DC
“Owning guns is not a right. If it were a right, it would be in the Constitution.” ~Alexandria Ocasio Cortez
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Joined: Feb 2004
Posts: 46,745
Campfire 'Bwana
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Campfire 'Bwana
Joined: Feb 2004
Posts: 46,745 |
$4k for an engine. $1k+ to swap?
10mpg to 20mpg.
10,000miles
1000gal gas x$2.80= $2800 500 gal dsl x $3.40 = $1700
So, you might recover $1100 per 10k miles.
40 or 50k miles to break even. Bet you won't drive that in decades if it's a barn dweller. Plus, if it now get 12 or 14 mpg, your payoff just got worse.
I love the torque and performance of a Cummins12v, many who are used to gas engines don't like the turbo lag, and high torque/low horsepower profile.
Always hearing how Chevy or Ford diesels are better, just because they are more like what car drivers are used to.
There's no way you're doing that swap for $1k,
Camp is where you make it.
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Joined: Feb 2004
Posts: 46,745
Campfire 'Bwana
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Campfire 'Bwana
Joined: Feb 2004
Posts: 46,745 |
14mpg would be almost double what its getting now. Its gets 9 on highway and 8 just running around. I know your's is a 3/4 ton but, are you running the stock motor? I had a 78 F-150 with a 351M/4-speed trans and a 79 Bronco with a 351M/C6 auto and it was a tale of 2 motors. The 79 was stock except dual exhaust. It was plenty fun for a 16-17 year old kid. But, It got about the same gas mileage as you're getting. My 78 which I did an amature resto on, was a different tale. It had mild cam of unknown specs, (stock valvetrain) otherwise, stock distributer, new plugs, wires, filters, an edelbrock 4bbl carb and intake, headers, and dual exhaust with no name glass packs. After that it got a legit 14mpg.
Camp is where you make it.
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Joined: Dec 2010
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Mine is stock except for RV cam and dual exhaust. Has c6 auto with 3;54 gears and on a good day straight down interstate at around 68mph it gets close to 9. Be hard to add 5 mpg to that.
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Joined: Oct 2015
Posts: 249
Campfire Member
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Campfire Member
Joined: Oct 2015
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Might be money ahead to get a gear vendors overdrive.
AKA glazer1972 Original Registration 09/07/03. 235 Original Posts. Re-registered due to issues with Private Messaging.
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Campfire Kahuna
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Campfire Kahuna
Joined: May 2011
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I've sure thought about it with a 95 F350 flatbed dumptruck I use. I get 5-6 mpg every day in that pig, and gutless as hell to boot. I don't think I could get 7mpg if I through that POS out of an airplane from 40,000 feet.
A Cummins would sure make a good truck out of it. Only reason I haven't done it is I have a pto for the dump body running off the Ford auto trans and I wouldn't want to keep the auto. Don't want to lose the pto as it cost a couple K when I had it installed.
_______________________________________________________ An 8 dollar driveway boy living in a T-111 shack
LOL
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