I didn't do anything today, but, a week ago Friday I filled both tanks for a trip to the Eastern shore with a load for my storage unit as part of the move. I got caught in a backup on I64 and had to go across town in Norfolk. I sat through a number of light cycles at Military Highway and Princess Anne Rd. I returned to Newport News Monday and didn't drive it again till yesterday.

On a return to the Eastern Shore, I was still running on the front tank until it ran out at 219.6 miles. Using the 19 gal capacity I got 11.557 mpg, or a 15.57% increase over the 10 it got when I first bought it in 1994. Not bad for a 7500lb dually with a 460.

 

Not bad at all. Dad's truck currently gets 10.5 with the 351M and can't tow or carry even close to what yours can. However, with the other engine and the ZF5 things will be different. Some day.

 

I'm still looking forward to you finishing the ZF5 Swap. I would love to see the gains that you would get with that.

 

Thanks. Me too. But, with all the help I'm getting in the thread on that I'll get there. Maybe not all that quickly, but I'll get there. First the engine, which is now going back together, then the machine work, and then the swap itself.

Then we'll know what the specific gains are for the ZF5 as the only change that would modify the MPG is the NP435 to ZF5 swap - meaning the 1.00 to .76 top gear difference. Yes, I had the heads worked on, but only one exhaust valve was truly leaking and it was just a small leak. So, the MPG gains from that will be so small as to be unmeasurable.

 

My biggest gain probably came from the OD 4th and lock-up converter in the E4OD.

 

Yep, me too. But, in my case the "converter" is 11" in diameter and the lockup is controlled by a wide pedal on the left, not the skinny pedal on the right.

I can't imagine that the MPG diff between Dad's 351M, at 10.5 MPG, and Rusty's 351M, at 14.6 MPG, is all due to the C6's losses and those of the torque converter. Dad's engine doesn't run nearly as well as Rusty's, and the leak down test showed part of the reason why, with the other reasons having to do with the RV cam and the parts stamped "Edelbrock" resting on top. So, we'll never know for sure the difference between a C6 and an NP435 because I'm not about to put the Zf behind Dad's engine just to test, but we should have a good handle on the difference between the NP and a ZF - almost all of which will be due to the OD.

 

If your swap is a success (with a lot of off the shelf parts & very little fabrication) & the gains are great. I'll think about this swap for my dent in the future.

 

There are two engines behind which Ford never put the ZF5 - the 351M and 400. All the others should be a fairly reasonable bolt-in swap. But, those two engines will require a spacer for the flywheel and pilot bearing, as well as the ring gear of the flywheel moved forward and an auto-tranny Windsor starter used to get the longer throw. IOW, save for the spacer it is doable with available parts, but the spacer will be the hard to come by piece - unless someone starts making and marketing them.

 

Not so likely given that Ford hasn't produced any since the early '80's.

Really, the 351M/400 was envisioned as a way for Ford to put a smaller displacement engine in front of a heavy duty Lima driveline for light duty trucks and '70's Luxobarges.

 

I didn't want to mess with a manual transmission in a tow vehicle. I have done it in the past and really didn't like starting on a slope with a load. It is interesting to climb out of one of the CBBT tubes in OD at 15-1600rpm and never come out of lockup, or even better down around 1200rpm and still never come out of lockup and watch the rpm and mph slowly climb. That's called torque.

 

I've been paying attention to that thread. The spacer is the only thing I'm worried about for the swap. My thought is now... how would I go about making a spacer for the ZF5 to the M block. It sounds expensive for thoses who don't have a lathe...

 

Yup, but several of us on here have them 'cause they are good truck engines - if built right. But, probably not nearly enough to get the spacer made commercially.

Yes, that's torque. And, I like that you can get down on it and still have it locked up. That's the way it should be, but I've never seen it before.

I will have the CAD drawings for the spacer available, and if I can make it then any machine shop you find can make it as well. After all, I have a whole two semesters of community college training for lathe and mill work, so any machinist is far beyond me. FAR.

 

Easy and inexpensive enough if you were to share an "as built" CAD file with other members it could be reproduced in almost any machine shop at nominal cost.

 

I'll certainly mod the file to "as built" and more than happy to share it. In fact, I plan to write up a how-to on the swap of a ZF5 into a truck that previously had a C6 and 351M. Maybe something a bit shorter than the 13 pages we are currently up to in Dad's ZF5 Swap.

 

So far the ZF5 thread is interesting even if it is a little above my head engineering wise. You're thinking about a rewrite for the ZF5 swap ?