4.0 swap ahead

[PetroleumJunkie412]

What transmission is in your B2?

 

[four.on.the.floor]

Fm146

 

[PetroleumJunkie412]

So, your transmission is going to die a violent death.

Fm146 won't handle a 4.0 or built 2.9 at all.

 

[alwaysFlOoReD]

Sure it can. Just don't be dropping the clutch. I used my b2 with 4.0 and stock trans for 2 years of snow plow duty.

 

[.38spl]

“Truths” I’ve read here:

* You can’t run 33’s on a 7.5
*You can’t run 33’s on a Dana 28.

All these rigs are on stock axles, running 33-35” tires. Everything you read here says not to. Ive talked to guys running 7.5/D28 under 302 and 351’s. It’s all in how you drive it. Be gentle. I really expect to have to rev and drag the clutch less with the added torque of the 4.0.

 

[PetroleumJunkie412]

...let me correct my statement.

A Fm146 will not survive my driving style ?

 

[rusty ol ranger]

The 7.5 is a fine rear end.

There used to be a guy here back in the olden days who had a 1st gen on 33s powered by a 351 windsor sitting on a D28. Ran it that way for a while and never snapped it to my knowledge.

Also, IMO, swapping a running 2.9 for a 4.0 isnt a worthwhile swap. You might as well go 302.

 

[19Walt93]

As the guy tasked with curing Fairmont vibrations in 1978, I'd like to correct the statement " a 7.5 is a fine rear end" to read "a 7.5 is a piece of crap". I lost count of the number of ring & pinions I had to replace due to excessive runout. The procedure for setting up the carrier bearing preload was a pain in the butt.

 

[BlackBII]

The 4.0 is a great engine to swap in place of a 2.9; it's bolt in with all factory parts and you retain your transmission, transfer car, driveshafts, exhaust, motor mounts, radiator, etc, etc and you gain a ton of torque while getting close to the same mileage.

I have been running my 7.5 with 33's and a locker for over 10 years without issues. The Dana 28 is quite undersized for 33's and a 4.0, but as long you're nice to it it'll work fine.

 

[bobbywalter]

for sure driver style is the major factor for the most part. BUT....you will have to winch to go where i like to go with a dana 28 and aggressive 33 inch or bigger tires......if your running a 28 with 33 or larger tires and never broke it...your boring. or have not been challenged yet. its all in where you go or where you live.

i couldnt keep a 7.5 and d28 in a stock truck with a 2.9 and failomatic on 235's. jim cruised around for years with a mild v8 and got along fine.


it is clearly a me problem.



so i agree... drive it and upgrade when you have to...IF you have to. they are making some shafts for the 28 now that are better. just may be all you need..

the 4.0 is the ideal engine for a b2 for all of the bolt on reasons stated. and an 80's 150-180 hp 351 with a c6 is a hell of alot easier on the drivetrain then a fresh 4.0 and 5 speed. it is the 351 version of the 2.9. with a 4.0 most only look at the peak numbers when comparing it to the 2.9 and other rbv engines....you would have to be retarded to drive them back to back and think a 2.9 is even close. the 4.0 pulls 30 to 50 ft.lb. or more torque from 1000 rpm up. then there is heat.....v8's make lots of heat and add weight. i love v8's....but with what is available now....i would rather have a ecoboost 4 whixxer....especially in a b2. perfect balance and ridiculous low end power. but the d28 would be hating it. superduty axles are cheap now.

good times to build these rigs.

my 4.0 b2 ate up several clutch rings (exploded hub bodies).... 9 inch rear axles and differentials....and a few 146 transmissions...rear springs...and cleared out my known supply of eb d44 stock shafts. i have to upgrade front shafts now. cant find any more 260 shafts used.



even my 110 hp ranger breaks dana 60 stuff....and its slower then smoke off a fresh pile o sheeit. so have fun.

 

[SenorNoob]

Just my opinion, but the FM146 seems plenty strong enough to me. I've done countless burnouts with 255/70R16's, the ole FM146, and 3.73 gears. Now when I lock it in 4WD that's different. It just smokes the clutch. Doesn't even move. But, I still have the 2.9 flywheel and clutch that was fried when I put it in 5 years ago.

 

[truckerdawg]

I am glad I came late here. A 2.9 better than a 4.0? My old 2.9 had head work(89-90tm heads), larger valves, solid lifters, aftermarket cam, larger throttle body on a 5 speed 3.55. And yes it was way better than the stock 2.9 but they still have that pesky head issue-I ran it hard because that is the way I built it. After 150,000 miles on the built motor one of my heads cracked-it was full on antifreeze and the water pump was working. However, my built 4.0 is way better when it comes to highway driving(ease of passing), pulling mountain grades in 5th gear, and racing from a dead start other vehicles -shocked at the quickness of an old BII. The 302 fuel injected swap with a 5 speed is a major undertaking compared to the plug and play I had with my 90 BII 4.0 swap. My 4.0 will hit near 6000rpms, not as much as the 2.9 did but it gets there a lot faster.

 

[PetroleumJunkie412]

I am glad I came late here. A 2.9 better than a 4.0? My old 2.9 had head work(89-90tm heads), larger valves, solid lifters, aftermarket cam, larger throttle body on a 5 speed 3.55. And yes it was way better than the stock 2.9 but they still have that pesky head issue-I ran it hard because that is the way I built it. After 150,000 miles on the built motor one of my heads cracked-it was full on antifreeze and the water pump was working. However, my built 4.0 is way better when it comes to highway driving(ease of passing), pulling mountain grades in 5th gear, and racing from a dead start other vehicles -shocked at the quickness of an old BII. The 302 fuel injected swap with a 5 speed is a major undertaking compared to the plug and play I had with my 90 BII 4.0 swap. My 4.0 will hit near 6000rpms, not as much as the 2.9 did but it gets there a lot faster.

Bumper to bumper, chain em up, let's go.