Zf5 swapping my t19(i think) 351m '80 f250

[MrRy]

I love the 4spd, however with the 3.54 gears and running a 32" tire the engine is turning at 2750 rpm and DRINKING fuel.
 To help remedy this I've been attempting to research the Zf5 trans swap.
Can anyone enlightenin me on what pitfalls I may encounter?

[Rembrant]

I can’t help with the 351M or the ZF5 specifically but I just did an M5OD 5spd swap in my 1980 F150 so I can assist with the modifications related to the cab and pedals, etc. I’m traveling today but will be back to my computer tonight.

[ArdWrknTrk]

You'll need to swap to a hydraulic pedal box, and these aren't a direct swap into pre '83 trucks that had a mechanical linkage.
You will need a new clutch that accepts the larger diameter Zf input spline.

The Zf will have to come from a 460 truck because they have an integral bell housing.
You will also need the crossmember, mount and raised tunnel cover from an '88ish truck (or cut the transfer case stick hole in a later raised cover) because around 1990 the Transfer case lever goes through the side of the tunnel, and you probably want to avoid cutting your floor and finding a new carpet.

Other than that the only problem I had with my Zf swap was finding a starter that would last more than a week.
I have a PMGR starter now.

[Gary Lewis]

Welcome to the Bullnose Forum!  Glad you joined!  

You probably didn't see the email that asked you to go to the New Members Start Here folder, read the guidelines, and then start an introduction thread about yourself and your truck.  That email seems to get lost frequently, but the main thing is that you've had a chance to read the guidelines, where are kept there.  We hold everyone to them so want you to have had a chance to see them.

As for MPG and the 351M, there are at least two problems.  One is that the original timing set was retarded, so replacing it with a straight-up set will help.

The other is the tranny, and a ZF5 with the OD will certainly help.  BUT, you cannot just bolt a 460's ZF5 to the M-Block and get it to live.  That's because the flywheel on a 460 sits ~3/8" farther back than that of the M-Block and the input shaft will JUST BARELY reach the pilot bearing.

There are a couple of solutions to that, but the guy that has them is Tim Meyer of TMeyer Precision Automotive Machine.  There's a discussion about all of this on the ZF5 Behind a 351M or 400 tab on the page at Documentation/Driveline/Transmissions/Manual Transmissions/ZF5.

With Dad's truck, which had a built 351M and a ZF5, I got ~14 MPG at 65 MPH.

[MrRy]

Good Morning, So from the information yall have just given me im finding that this swap is WAY more involved than i had thought.
   I did see that the timing set on the M family of engines was retarded. Will a simple timing chain and gears solve this? Or a cam swap?  
   As far as displacement, from my understanding its just a crank and piston set away from being a 400, correct?

Thanks Ry

[ArdWrknTrk]

Yes, just a simple timing set with the keyways aligned will eliminate the 4° cam retard.

And as Gary's sig says the 400ci displacement is essentially a factory stroker.
I'm not sure, but I think you need rods and not pistons.
Gary can better answer that question, as he is more fluent in 335.

[MrRy]

Awesome! So, I'm curious if I could "skip a tooth" and obtain an acceptance advance of the cam with my existing factory timing set...?
 Do fords have clearance under the timing cover for a double row set?
  I presume after the cam advance I will pick up some noticeable power and fuel economy,  or is it not that dramatic?
 

From my understanding,  Cleveland timing set, cam and heads all are especially interchangeable to the M & 400 engines, the difference is block deck height,  crank and bell housing pattern (big block pattern) as well as several other subtle and not so subtle differences.  

[MrRy]

Edit:   Sorry.   I'm trying to learn how to better use this forum through my mobile device.
I should probably change this from the zf5 to something else, or let it die entirely.

Ry.

[Gary Lewis]

Actually, it is just the crank and pistons that Ford changed from the 400 to make the 351M. The rods are the same.

I slipped a 400 crank and TMI pistons into Dad’s 351M block   To make a 400.

[ArdWrknTrk]

Not unless the gear has 90 teeth. 360/4

I know for the 460 a basic Cloyes double roller timing set is less expensive than even the stock replacement EFI 460 set.
It's around $42 on Amazon, but I'm not sure who stocks a 335 engine timing set.
I'm sure Tim does, but I know nothing about pricing.

[MrRy]

Okay,  so most of what I have read about the 351m/400 engine is correct,  woot!
 If I'm not mistaken I read a Ford document somewhere that the rods are forged, not just cast?
 The main caps are 2 bolt?

Why is there so much stigma around this engine family not wanting to rev?
A simple cam/ valve spring upgrade should solve any issue completely.... or am I missing something?

 Ry

[MrRy]

Okay,  so do you know if the Cleveland/Windsor timing sets are compatible with the 351m/400?

I'm not well versed in the Ford stuff.
My prior mechanical experience has been the other brands.

Thanks

Ry

[ArdWrknTrk]

Cleveland timing sets are.
They are 335 series engines after all.

I think one of the big problems with these engines are low compression height and open chamber heads.
I am pretty sure Tim offers pop-up pistons to at least get some compression and squish.

If you want to see what's possible in a bulletproof streetable  engine have a look at the charts and dyno pull videos in Gary's thread.

If stuck with some kind of factory iron head ditch the wheezing 2V heads and find some Cleveland 4V-heads.
Intake adapters might be needed. I'm not sure of everything manifold manufacturers still offer for an engine OOP for 40 years.

[ArdWrknTrk]

I see the Comp Cams Magnum true double roller (2121) on Amazon for under $60 Prime.  💡

[MrRy]

Ahh Mr Jim,
   I should have thought about the 360°of rotation and divided by 4 prior to my A.d.d brain spouting off a question faster than the rest of the brain could process..


Sincerely,  thanks yall. Will leave this post to die out and pose other questions in other posts.
 

Ryan