Hey all, I finally finished my F600 camper build. It started as a 75 uhaul that I pulled out of the ditch. I redid the full brake system, got some military deuce wheels and tires, built a flat deck and repainted. It's come a long way over the past few months! I finally put my camper on and took it for a ride down the highway.

I found that the fastest I could get it up to is about 80kmh (50mph). It seems incredibly underpowered and I'm just wondering if that is normal with these trucks. I know that the 42" tires probably kill a bunch of the power but for it to be that slow? The camper weighs 2100lbs and the deck maybe 500 so I can't see it being an issue of over weight. It was backfiring through the carb quite severely under load so I set the ignition timing to 7 degrees btdc. The carb air mixture has been set to 2 and a half turns out. It runs smoother since those changes but still not 100%. I replaced cap, rotor, wires, plugs, fuel pump as well.

If that is normal for it, what are other options for motors? I know the 361 and 391 are basically direct bolt in but I have a feeling it will be hard to find one. What's all needed if I were to swap in for example a 400 from an older f250? Is there a bug difference between the pickup engines and medium duty? I'd like to keep the 4 speed trans that's currently in it if possible.

Some pics attached from when I got it until now

 

1964/78 FT engines: 330 2V M/D; 330 2V H/D; 361 2V or 4V (1974/78); 391 4V

Most common is the 330 2V M/D

If it's still backfiring, a worn (loose) timing chain and camshaft sprocket (may have stripped) are the usual culprits.

 

Yes 330s are underpowered.

Your taller tires are going to eat some power. With your 50 MPH, is that corrected for the taller tire?

If I read some earlier posts correctly there is a question about axle ratio. This is a quote from a Numberdummy decode:

"All I can see of the AXLE code stamped on the Warranty Plate is 2. It should be followed by a letter, but I cannot see it.

2A & 2T = Rockwell-Timken model R170 Rear Axle / 4.33-1.

But the separate tag says Rockwell model F106. In the 1973/79 600/900 truck catalog application chart, there is a Rockwell F106 listed for 1973/79 F600."

If this was a low profile U-Haul truck with 19.5" wheels, a 4.33 axle would make sense. With your tires and a 4.33, you might be power limited in 4th gear and not be able to pull that gear easily.

If the axle was changed out to a 7.something ratio, you would be rpm limited, and hit the governor at probably 55mph if you still have the U-Haul governor.

Is your engine screaming or just unable to pull the gear?

 

OP says he cannot find another FT engine.

Since he lives in the frozen north (Alberta Canada, unlike you and I that live in sunny SoCal-where there are plenty of these trucks in junkyards), I can see that finding an FT engine and a rear axle may be difficult.

 

I think his 330 needs a tune up, maybe the timing chain as well.

Next step is either smaller tires or a different axle ratio or a different engine or an overdrive unit.

X2 on the 400 not being the answer.

Can you find FE engines? The front cover and bell can interchange, a bushing for the crank would be needed in front, and some mix and match on the clutch side.

Do we know if this is MD or HD?

 

When someone needs something for these trucks they cannot find, I call Marty at SoCal Truck Wrecking (on Alameda St. just north of the former Firestone plant) to see if he has it...or can get it.

SoCal has been owned by the same family since 1929. I've known Marty since 1967 when both of us were young un's and thought we knew everything!

4th digit of the VIN is the engine code ~ 1966/78 FT: C = 330 2V M/D; D = 330 2V H/D; E = 361 2V/4V; F = 391 4V

 

I went back, his was Z, special order engine. U-Haul did 330 MD and the 359s iirc from previous U-Haul discussions.

Anyway, a basic check on that engine and a "tune up" might bring some power back.

To the OP, have you done a compression check on that engine? I know you've been working on this for a while.....

 

The 359 and 389 are nothing more than a 361 and 391 detuned for smog.

1973/78 F350's made exclusively for U-Haul have the 330 2V M/D FT engine.

I went to work at Coberly Ford (Washington/Figueroa) in 1978, then I found out they had the U-Haul account...which meant than when the brake mechanic wanted drums, I had to go get them off the shelf.

Those drums were heavy as hell, the only blessing I had, delivered them to him in a golf cart. The mechanic was as tough as nails, we called him "the razor."

Coberly fired the parts manager three months after I went to work there. The new parts manager was a martinet. I left (went to Crenshaw) as did three other parts guys.

A year or so later, Coberly 'folded the tent' and Crenshaw got the U-Haul account. Crenshaw didn't have a golf cart.

Several years ago I was talking to a FTE member at a SoCal chapter GTG, the subject turned to Coberly and he said he was married to Mike Ikeda's daughter.

Mike Ikeda was the U-Haul brake mechanic we called "the razor!"

 

To answer a couple of the questions, it was clocked at the 80kmh with GPS, not speedometer. It feels completely gutless. 1st and 2nd gear are fine, I can hit third okay but fourth just has no power at all. If I'm in 4th and approach a slight incline I have to downshift to third again and speeds drop to 70ish.

I understand the mounting is different for the 400, the motor mounts would be not a huge deal to weld up as long as I could mount it to the tranny without too much modification. The current motor may benefit from a tuneup but it's pretty tired. It has a heavy leak from the rear main seal and it's starting to burn oil. I have to pick up a compression tester and see how that is. I have a feeling I'll likely just need to find a motor and do a rebuild then swap in. I'd love to diesel swap it down the road but for now if I can find something that is a relatively direct swap I'd prefer to do that.

 

I had a 68 cab over 16 foot flat bed stateside dump truck with the 330 and a five speed . It was a big heavy truck and could handle 8 tons easy plus it had big brakes and on top of that it was at one time a 10 wheeler !! With the 330 !! So the truck was not quick by any means but with a full load it would get up to freeway speeds like many older trucks loaded down . That motor ran like a sewing machine ( perfect ) never over heated and was fair on gas . So looking at your set up I would say the engine is not running at its best .

 

Also you might want the check compare the power ratings between the 330 to the 400 m that 351 400 is no power house either plus that 330 is an industrial engine !!! There is one on CL here in the Bay Area . Stay with the 330 it will be an easy swap as well . Plus a lot of them flooting around with low miles . The 330 medium duty and I think thier was a 330 heavy duty ,, maybe

 

I bought a 1958 F600 more as a toy than a worker. It had a 292 Y-block, 5 speed (not OD) and an Eaton 2 speed (6.33/8.81) rear axle. It didn't take long at all to determine that that driveline combo was not going to work for me.

The truck is now motivated by an '88 7.3L IDI, ZF5 5 speed (OD), a Spicer 3 speed auxiliary and a Dana 80 with 3.73 gears. I have only driven it on the county road by my house but it now does what I want. It needs a couple of more things fixed so it can pass the state inspection and I can get it licensed and take it out on the highway.

 

We use to call those 351/400's moose motors. One thing they did well was use fuel.
With the 400 or 351s you need a bell housing for your 4speed, mounts, clutch linkage
exhaust all different. My first suspect is a stretched timming chain makes the valve
train run retarded and fiddling with the dist. is only a bandade it ain't right. We use to
say old rule, 80,000 miles its timing chain time ! Plus I wouldn't doubt U Haul turned
the governors down because most renters are not truck drivers. You got a nice looking
truck, so do up the engine. For a direct swap any FE will slide right in there .......sam

 

292 was a good one for work . I think It weighed more than the 472 cad engine . Some of those old 292's came in the cab overs and the ram horn exhaust , tough to find these days . I was also wondering what the difference is between say a 361 to 360 o r a 391 to a 390 , 330 ? Also .. Is it true that heavy haulers have smaller valves as to not over heat , when I was building my motor the machanic ask me what I would be using the truck for and he didn't suggest using the bigger valved car heads for truck hauling a trailer up a hill

 

The 330 is definitelly underpowered. However, get it running right, it should never backfire out the carb. Do a compression check and report back.

The top bushing in the distributor might be warn, and the dwell (and timing) is walking all over the place. Pull the distributor cap, rotate the engine until the points are closed, and pull back and forth on the rotor in the direction of where the points contact the shaft. If the points open and close, the top distributor bushing is shot, and you need a rebuild (check the rebuild for the same issue, sometimes they don't replace the top bushing).

If you don't have one, get a dwell meter. Better yet, might be to replace the points with a Pertronix, get a hotter coil and see what happens. Even if you swap out the engine, the Pertronix will work in the new one too unless you go way forwards in time