"F" 250 as the ultimate tow rig! Can it be?

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"F" 250 as the ultimate tow rig! Can it be?

January 03, 2017, 10:08:32 PM

Since I finished my T-Bird Drag Car, I thought it was important to have the correct tow vehicle to get me to the track. I decided to set some limits because it's as easy as buying a new truck and going into debt by a whole lot.
#1- it needs to be from the same era as my car (look period correct). That limited me to OBS F series or E series van as well as a nice Crown Vic or Grand Marquis. A wagon would be awesome!
#2- cannot have a 460, let's face it I could not afford to race after gassing this pig up for a day at the track. 10mpg is no go in my book since this would be a second vehicle and I would be using it on a daily basis going to and from work. It must be economical in today's sense.
#3- it had to be Windsor powered! I have a whole garage of squirreled away parts from over the years and I could make an awesome EFI Windsor something.....

My buddy offered me this beautiful 1988 F250 XLT lariat that his dad willed him when he died....it has a 460 and C6. That was against rule 2.... So we started talking. There were hundreds and thousands of these trucks built with a 460. Many were for sale cheap! That was because of the fuel consumption. Can a truck like this be revised to today's standards of economical by using Junk Yard stuff for the fraction of the cost of something new. The cost of replacing everything cannot even be close to the cost of buying a new truck.

"F" 250 as the ultimate tow rig! Can it be?

Reply #1 – January 03, 2017, 10:19:02 PM

These thoughts stewed for a few months and became all but forgotten and then it happened! I found a 1988 f250 XL model with a gacked 351 and a 5 speed on Craig's List just down the street in Chula Vista. I went and checked it out. The owner would not come down 1 cent! I looked the truck over and was as giddy as a school girl. It had a complete set of unrashed real deal ALCOA wheels and the desireable ZF 5 Speed and not the Mazda turd.

After getting it home courtesy of AAA, my neighbor and I tore into the truck. Motor and tranny out, drive shaft, motor mounts, tranny crossmember, pedal bucket and steering column, wheels off and viola the frame was bent behind the passengers front tire....well that's ok. Call the Spers, instant $200!

"F" 250 as the ultimate tow rig! Can it be?

Reply #2 – January 03, 2017, 10:54:54 PM

Over the course of the past year I had the ZF rebuilt by a racing buddy for the cost of a 351w block and $300 in rebuild kit. The 351 required a complete rebuild, so an over bore of .030, hot tank, cam bearings and a lot of elbow grease! My friend with the nice 1988 f250 and I discussed the possibility of a gas mileage 393.... Was it a possibility? My old tbird would get 24-26 mpg with stock ford stuff with the exception of 3.55 gears and an HO intake. I did not see why a 393 would get less than 20. Maybe I was dreaming! But either way I thought a lot of it had to do with port velocity and air flow being high at low engine speeds and the cam in the tbird, so I started by planning the goals.
#1- must get 20 mpg! While Towing this was never going to happen and was unrealistic but daily driving, that's real!
#2- it must go 500 miles on a tank of fuel when towing. If it ended up getting 10 while towing, it needed to carry some fuel. The truck spends a majority of its life not towing, but when loaded it had to have some range.
#3- it must have some flair and charisma. Low engine speed means larger cubic inch generally for good low grunt and it can be complimented with longer rods for more grunt below the curve and in normal operating range.

"F" 250 as the ultimate tow rig! Can it be?

Reply #3 – January 04, 2017, 03:13:38 PM

Love love love my "OBS". I literally just do not like any Ford trucks made after these. The styling just doesn't even hold a candle to it for me. Kinda goes against my policy of no ABS but you can't win them all right?

Good luck with the build! MPG may be a tough one, though if you spring for a really nice high-flowing top end setup you might get what you're looking for.

"F" 250 as the ultimate tow rig! Can it be?

Reply #4 – January 04, 2017, 11:04:53 PM

Ok, well the reason the post has so much info is for the back story, but to cut to the chase.....I have already started and am almost done with phase 1. I bought a much more used truck that was much newer but was closer to what I wanted. I found a 1994 F250 2wd reg cab long bed. It was sporting a 351 that did not run and a "fresh rebuilt" E4OD. Well I pulled the motor out after finding 5 quarts of water/ antifreeze in the pan and did a cheap spray can rebuild, re-ring and bearing job to get it up and running. Found 1 bad rod that apparently got hot and was deformed on the big end. The crank was junk, but I had the crank from the beater 88 with the ZF 5 speed. Swapped the crank, used an 88 f250 rod and bought 1 piston. The best part was the F4TE block in the 1994 truck. Roller 351! I can use most of the parts stashed from the tbird and 23 years of 5.0 parts ding. I used the stock SO 5.0 cam from my tbird, a lightning lower intake, some cobra roller rockers and a set of AFR 165 cylinder heads with 60cc chambers. I had scored an awesome set of doing Thorley try-y headers for a bronco at the annual swap meet that were stainless for $65 that were almost $700 new. Thought they might fit, and they do....awesomely! I has a few race parts left over from a blown up 302, timing chain, t bird valve covers and a New NOS ford timing cover I bought almost 15 years ago.
So things I learned.....the low end on this 351 is awesome, I don't know if I need a 393. That may be overkill. The Trucks are all batch Fire efi and not sequential. Therefore the 302 cam would work well in the truck temperairally until I finish the 393 and swap over. A fuel rail from the 88 F250 is a direct bolt on and will accept a 5.0 mustang adjustable fuel pressure regulator. Speed density batch fire is very acceptable to upgrades as long as the cam remains very factory. The 351 pulls 23" of vacuum at idle and really idles smooth. I swapped the mechanical fan for an electric flex-a-lite and added a dual battery setup from a powerstroke diesel. I added a 33 gallon bronco tank in the rear.

"F" 250 as the ultimate tow rig! Can it be?

Reply #5 – January 04, 2017, 11:20:09 PM

I have been focused on my interior and the towing capability recently. The fresh rebuilt tranny was slipping like mad and did not enjoy shifting promptly. I could not tell if it was the programming of the PCM or just poor rebuild. After flushing and shift kit, I decided to ZF 5 speed the truck. bought a clutch from center force, new flywheel and master/ slave cylinders with throw out bearing. I hit the junkyard and found a 1992 f150 with a manual and got a 92-96 pedal bucket and the wiring harness from a manual and the computer from a f350 box truck. I need the front wiring harness that has brake controller and relays in the fuse box anyway. I also scored a slider back window and a set of seat brackets to mount a pair of lightning seats.

"F" 250 as the ultimate tow rig! Can it be?

Reply #6 – January 05, 2017, 12:44:36 AM

Id go with a 302 and highway gears. The zf had a super low almost granny 1st gear and with a manual while towing, staying in 4th isnt a big deal for hills. For every 1k in rpms, you use about 4x the fuel.

"F" 250 as the ultimate tow rig! Can it be?

Reply #7 – January 05, 2017, 02:37:12 AM

I am a fan of the OBS ford trucks as well. Have 4 of them. Two with 7.3 autos, one 7.3 5 speed, and one with a 460 5 speed. I agree with the notion that you can rebuild one for a fraction of the cost of a new one as long as you can turn the wrenches yourself.

20 mpg's does sound a bit ambitious from an OBS F250 gasser, but hope you can pull it off. Most F250's got 4.10's, but some 3.55 gears, synthetic fluids, non aggressive tread tires, front air dam, and a light touch on the throttle couldn't hurt. In stock form for a gas engine the closest Ford came to what you are trying to do was the 300 6cyl 5 speed. They pulled great and could do mid teens out on the highway.

Goal #3 was flair and charisma, made me think of this. Someone that pulls a 4 eye bird or stang to the track needs this.

http://ottumwa.craigslist.org/cto/5906984549.html

"F" 250 as the ultimate tow rig! Can it be?

Reply #8 – January 05, 2017, 06:03:28 PM

This van is the best! Too bad I already spent my cash on this truck. This thing is perfect! Just that stripe......it needs a purple one too before I commit to buy!

"F" 250 as the ultimate tow rig! Can it be?

Reply #9 – January 05, 2017, 06:10:33 PM

This weekend I will finish the ZF install and button up the column. I got a box of carpet, not for munching, but to put on the truck floor and make some exhaust. I should then be finished with phase 1 and can check some mileage as well as the charisma/cool factor!

Exhaust, I got a 4 inch diesel mandrel bent exhaust. It was half the price of most dual kits and will likely out flow them by a bunch. Just need to fab a Y pipe from the headers. I'll try and grab a bunch of pictures so anyone who wants to see this thing can check it out.

"F" 250 as the ultimate tow rig! Can it be?

Reply #10 – January 05, 2017, 06:16:05 PM

I have been throwing around the idea of putting a 8KC t-bird computer in the truck, use a car injector harness and move a few pins in the truck harness and viola, SFI speed density. No more batch fire. I think it may be worth a few MPG. I also have the A9P computer from when my tbird used stock ford 5.0 302 parts to make it down the track. I also have a 93 Cobra computer and MAF I could use, just requires to change the cam. Maybe use the custom 393 Schneider hyd roller cam I got made for low end? Your thoughts....anyone.

"F" 250 as the ultimate tow rig! Can it be?

Reply #11 – January 05, 2017, 08:08:05 PM

Quote from: Lightningbird;458810

SFI speed density. No more batch fire. I think it may be worth a few MPG.

Don't get your hopes up, SEFI mostly addresses emissions... If it would have increased MPG I'd think Ford would have used it in trucks sooner than the early '90s... The converted to mass air Stang I had lost .2 ET at track but did pick up approx 1mpg... I wound up converting it back to SD...

"F" 250 as the ultimate tow rig! Can it be?

Reply #12 – January 06, 2017, 01:53:06 PM

Thanks Tom, I was wondering if it would make a difference. Looks like it may be worth trying it before dropping $750 for a tune on the truck. I have found the fueling limitations of the stock computer. Maybe the 393 would be better because the RPM band may be better suited for towing vice this smaller 351 motor that easily turns up to 5K. I may try playing with fuel press before all. Seems like its running rich at idle surprisingly, 24# injectors may be too much. I used thin rings 1.5/1.5/4mm package with the napier setup and the H series Clevite bearings that had less bearing surface. It may not need so much fuel at an idle. After putting it together it only took 15 in/lbs to turn the motor over with no plugs. It may be fueling too much at idle.

"F" 250 as the ultimate tow rig! Can it be?

Reply #13 – January 07, 2017, 11:10:59 PM

Tom, this is what I was looking at that seemed to make a lot of sense.

http://www.fordmuscle.com/archives/2005/10/MassAirConversion/index.php http://www.fordmuscle.com/archives/2005/10/MassAirConversion/index.php

"F" 250 as the ultimate tow rig! Can it be?

Reply #14 – January 16, 2017, 12:34:55 PM

Ok, so ZF 5 speed conversion has not gone so well. First off, I had to make a harness for the transmission, not all that bad. Then I swapped the column that I got from the junkyard, it had a bad ignition switch that took 2 days to troubleshoot and narrow down the switch itself. That was difficult because I had messed with so many things making the harness I truely thought it was the harness but turned out to be the switch. That was most likely the cause of the junkyard truck being in the junkyard. Lastly was the transmission leaking tranny fluid out of the input shaft. I thought the front seal did not end up sealing. After taking the tranny back out, I found that the pilot bearing was too sloppy in the crank allowing the input shaft to work the bearing loose. This was a problem! Usually the crank is junk at that point or can be used for an automatic, but I bought the old school bushing for a SBF and dimpled it with a punch to swedge the bushing into place. I know this is a work around, but easier than the crank being changed or manufacturing a custom bushing, so thought I would try that first. I have not got the tranny back in yet as I had to take it out to replace the seal and verify all was good internally. Had to replace a synchro on 3-4 shift to correct damage from input shaft wobble. It should be back together soon and I can test it out.