Input wanted and some questions involving my 88 Bronco II

[901wd#2]

I think I may be tempted to leave the F-150 spring perches on my TTB and see if I can add another two inches of lift all around… may be a dumb idea though and I should probably not do that, lol

On my b2 with the 3” duff drop brackets the front sat near perfect.

The reg setup was jumped out duff coils and f150 spacers.

These are soft and stretchy,

 

[gaz]

@lil_Blue_Ford
Reading your question it sounds like your not certain where you want to go with the engine. I feel that is the first decision and will answer the remaining choices.

Having chosen the power plant, tire size is next based on your engines known max torque RPM and axle gear ratio. The selection of the most efficient tire size is simple math. With your tire diameter dilemma put to bed, it will determine how much lift (or trimming) your chassis will require.

I still like the output, economy and mannerisms of the 2.9l but sourcing OHV 4.0l components, while albeit more expensive, is much simpler. My mechanical mentor is very much in favor of me updating to the SOHC 4.0l platform; my #1 reason to stave that off is the OBD2 system. 5.0 power in a Ranger based platform is arguably the most natural matchup. The horse power to weight ratio is great, only giving up points to overall fuel economy.

I am spoiled with how remarkably flexible the OBD1 PCM remains. Never needing to consider the need to reprogram the PCM has opened my mind to a cost conscious world of fuel economy innovation.

RECOMENDATION
You state that you have a treasure trove of components to work with, just decide how tame or efficient this stock profile that you desire is. I'm a sucker for maximizing fuel economy. No matter where i live, i quickly become faced with undesirable commutes and do not appreciate the ever increasing credit cards exchange at the petroleum depot...if 75% or more of our nation's (world's) automobiles made 35+ mpg, how much different would it be???

In a Bronco II regardless of power plant, here is my immediate short order list:
• Explorer D35/8.8
• 4" suspension lift
• dual James Duff 70/30's on all four corners
Right there is the vehicle Ford should have marketed!! Whether you desire maximum efficiency (fuel economy) from a trusty ole 2.9l, the increased component availability of the more expensive to maintain OHV 4.0l, the improved power and torque of the SOHC 4.0L or a lock and loaded 5.0l set up...is the choice.

 

[Uncle Gump]

 

[lil_Blue_Ford]

@lil_Blue_Ford
Reading your question it sounds like your not certain where you want to go with the engine. I feel that is the first decision and will answer the remaining choices.

Having chosen the power plant, tire size is next based on your engines known max torque RPM and axle gear ratio. The selection of the most efficient tire size is simple math. With your tire diameter dilemma put to bed, it will determine how much lift (or trimming) your chassis will require.

I still like the output, economy and mannerisms of the 2.9l but sourcing OHV 4.0l components, while albeit more expensive, is much simpler. My mechanical mentor is very much in favor of me updating to the SOHC 4.0l platform; my #1 reason to stave that off is the OBD2 system. 5.0 power in a Ranger based platform is arguably the most natural matchup. The horse power to weight ratio is great, only giving up points to overall fuel economy.

I am spoiled with how remarkably flexible the OBD1 PCM remains. Never needing to consider the need to reprogram the PCM has opened my mind to a cost conscious world of fuel economy innovation.

RECOMENDATION
You state that you have a treasure trove of components to work with, just decide how tame or efficient this stock profile that you desire is. I'm a sucker for maximizing fuel economy. No matter where i live, i quickly become faced with undesirable commutes and do not appreciate the ever increasing credit cards exchange at the petroleum depot...if 75% or more of our nation's (world's) automobiles made 35+ mpg, how much different would it be???

In a Bronco II regardless of power plant, here is my immediate short order list:
• Explorer D35/8.8
• 4" suspension lift
• dual James Duff 70/30's on all four corners
Right there is the vehicle Ford should have marketed!! Whether you desire maximum efficiency (fuel economy) from a trusty ole 2.9l, the increased component availability of the more expensive to maintain OHV 4.0l, the improved power and torque of the SOHC 4.0L or a lock and loaded 5.0l set up...is the choice.

So, this was intended to be a modded 2.9 but it’s sat and now I suspect the block at this point likely needs torn apart and rebuilt. I don’t have a garage or the knowledge to do this myself right now and even if I did, I’m suspecting a likelihood of needing to have a machine shop bore it out. Which got me thinking that perhaps I should seriously consider changing the powerplant. Which lasted right up until I was offered a running 2.9 that greatly simplifies things since I can just bolt on the upgrades I was originally intending to use and already have. Reduces cost and time. When that 2.9 goes, then I’ll re-visit the idea of a different engine.

The core support has been modded already to a bolt-in, so re-powering later doesn’t require me to cut welds again.

So at this point, this thread is already helping me work through a revised plan.

The 2.9 with 3.73 gears and 30” tires will work fine. I’ve run that combo before on a B2. I’m also kind of sure it won’t be super happy about 31” tires though. Heck, my 5.0 Ranger isn’t super happy about 31” tires with 3.73 gears. So I either have to stick with the 30” tires or re-gear to 4.10 to put 31’s on the 88 and be happy with it. I do have a D-28 set of 4.10 gears and I have access to an 8.8 with 4.10 gears, but if I go that route then I have two potential sticky points… suddenly leaves me with a bunch of 7.5” parts and nothing to use them up on plus I don’t know how well the D-28 will hold up to 31” tires and I’ve already depleted most of my D-28 spare parts trying to keep it alive in my Choptop for longer than I should have. The 30” tires look like they may appear to be a little on the small side with 3” of total lift though, despite not making me change a bunch of stuff. I really didn’t want to mess with the axles because that’s more work, but…

I really just want to be able to put this thing together after I get the dump truck done and finally be able to drive it around. I’ve owned it for around 20 years and only actually driven it about a month before it destroyed its original motor. I’d like to build it so I’ll be happy with it and not have to keep making adjustments on the fly.

I am NOT doing a different suspension lift. My extended arms have been built to work with a 2” suspension lift. The truck is also getting a 1” body lift because I have it and it should give me a little more room to reach things when I have to do maintenance. I never really intended this truck to grow at all and now I’m staring down 3” of total lift plus bigger tires. I have 30” tires on it currently, but they are shot. It’s taller than I originally intended. I’m not lowering it back down though either. So it’s staying right where it’s at. I’m not building this for hard core off-roading. I’m building this for cruising around in and mild wheeling. Mostly just cruising around. 3” of lift is more than adequate for anything this truck is ever likely to see.

 

[gaz]

@lil_Blue_Ford
My experience with matching 2.9l, gear ratio and tire diameter is as follows:
• 4:10, use 32"
• 3:73, use 30.5

These numbers are for max fuel economy at 62.5 mph, so I expect you will have respectable results with those 30" tires using 3:73 gears.

 

[lil_Blue_Ford]

@lil_Blue_Ford
My experience with matching 2.9l, gear ratio and tire diameter is as follows:
• 4:10, use 32"
• 3:73, use 30.5

These numbers are for max fuel economy at 62.5 mph, so I expect you will have respectable results with those 30" tires using 3:73 gears.

I’m not really worried about max fuel economy (although a 2.3l EcoBoost with a 10-speed would be where it’s at for max fuel economy I’m sure). Not sure how it is where you’re at, but around here, if it isn’t uphill, then it’s probably downhill. There’s very little flat land, which is hard on fuel economy. A 2.9 with an A4LD in a B2 around here, well, with 3.73 gears it’s sluggish enough on 30” tires in my opinion. I’m not sure how acceptable it would be on 31” tires.

Now, that said, I’m also intending on doing valve body work on the transmission and doing some engine stuff (free-float rockers, gasket match porting, headers, MAF conversion, electric power steering, electric fan). I’m not entirely sure where that will get me in terms of performance. I do know that just the transmission work alone on my 92 Ranger with a 4.0, 3.73 gears and 30” tires changed it from a bit sluggish to being actually pretty nice and able to light up both back tires just by hitting the gas hard from a stop. So maybe with the mods I have planned for the engine and transmission 3.73 gears and 31” tires would be acceptable. I don’t really have enough information. I know 4.10 gears and 31” tires will be acceptable even without the engine and transmission mods

 

[gaz]

@lil_Blue_Ford
Mileage observed with 4:10's using 32" rubber (3:73 with 30.5 puts the engine at the exact same engine RPM per vehicle mph):
• 87 Regular cab, long bed LOADED to the max under fiberglass canopy with internal 3" rollbar, stock 2.9, electric fan, no A/C, headers w 2¼" mandrel bent exhaust, all synthetic fluids, drop in K&N, Accell 300+ ignition and Hypertech Stage 1 PCM CHiP while driven from San Diego to Seattle 28.1 mpg, trip average
• 87 BII, fully rebuilt 2.9, electric fan, no A/C, headers w 2½" mandrel bent exhaust, all synthetic fluids, drop in K&N, MSD coil and JET stage II PCM CHiP towing flat trailer loaded with 2 ORV's @ 2,300lbs from Seattle to Medford Oregon and back 24.8 mpg, trip average

Both runs were 99% highway through multiple mountain ranges, trucks were lifted (5" and 4" perspectively) kept purposely at a constant 60 mpg on pump premium. These are my two standout fuel economy talking points. Just sayin, its why when I read about a operator/owner experiencing difficulty maintaining highway speeds into a headwind or while ascending a HiLL, I simply can't relate.