Hey y'all I just pulled my engine to see why she done won't trun over. I have a 84 full size Bronco with the 300 I6 and 4 speed overdrive MT and 8.8 axle with 3.08 gears. once I pulled the 300 out of her and tore into it I was looking on creagslist for a big block V8. I found a 70 something Ford 3/4 ton 2wd with a 400 and a 4 speed MT too boot. I was thinking about buying the truck and putting the engine and trannie in my Bronco. But I was wondering about the wiring harnes. what would I do about that lil issue?

I apprecate any and all info and incite about this.

 

Are you planning on using the Ford ignition setup or an after market system? This will determine the bulk of the necessary wiring. The differences in wiring harnesses will be primarily for any emissions/accessory equipment beyond the ignition system. The 400 was equipped with either the traditional "point & condenser" ignition and later the Duraspark system which requires the appropriate control module. Aftermarket ignition systems will either use part of the original wiring or give instructions as to how to properly wire them.

 

Yeah i'd say go with 400 that would be cool. Definitly get a duraspark ignition. Or even get DUI from performance distributors, its a one wire hook up. While your at it do a 4 bbl intake/carb and a set of headers to wake that beast up.

 

I was just going to keep the ignition system stock. I also removed the smog pump and some of the emisions controls from the 300 when the engine was still in the bronco because there were no hoses going to it and no pully either. So I recon that the emision part of the harnes will not be needed. I also have a A/C system in the bronco that I would like to keep, although I've been told I need a new A/C compressor vbecause mine ceased up.
Also do you know if I could put the 3/4 ton axle under the bronco. that way I know that the axle could stand up to the toqure of the 400. Again also would I have to fab up new motor mounts and what elce would I have to fab up to pull off the 400 swap?

by the way, sorry for any spelling errors. It never was my strong point.

 

What rear axle do you have in your bronco now? Either a 8.8 or a 9". If it is a 9" i would leave it in the vehicle. Your going to need different motor mounts. The 351m/400 was an option in the 80's trucks so the swap should not be to difficult.

 

I have the 8.8" with 3.08 gears out back and up front I have the Dana 44 IFS with 3.07 gears. But I dont even kick her in 4wd any more. So I would more then likly just take out my front drive shaft.

 

Dana 44 ttb. If you drive this bronco hard, or have larger tires, the 8.8 wont hold up very long to that kind of torque. And why take the front driveshaft off?

 

Well I would take off the front drive shaft to A) lighten her up a lil and B) so if I do put the axle from the 70 something ford under my bronco, I don't have to worie about accidentily puting her into 4 high and striping out my new Waren manual hubs I just put in her or damaging my T-case.

I am guilty of the topping out 1st, 2nd, and skiping to 4th gear and just driving normal once I put in into 4th.
I'm also guilty of trying to drift on pavment and trying to power break on gravel.

 

that 400 in stock form isnt going to put out that much torque to hurt the 8.8. it maybe puts out as much as an efi 5.8 torque wise. i would personally run another 300-6. they are great motors. that 400 is heavy, and suck on power and gas. power can be had but with a bunch of work.

 

I guess I cant see the purpose of swapping in the 400 and leaving it bone stock. And it dont take much to really wake one up...

 

I currently own a 400 and a 300 and until I warmed up the 400 the 300 made as much power and used half the gas. Now with the cam carb and intake the 400 is like a different motor but bone stock, well it was a bad 8mpg joke.
-Johnboy

 

the 400 requires massive head work, cam upgrade, compression increase and proper intake to make great screaming power. otherwise its a boat anchor, and expect these upgrades to not be cheap for the 351m/400 family. Ive seen this motor built and toss a 3/4 hiboy ford on its top because the guy got on the power at the wrong time going from gravel to pavement. He also had a built C6 to use that power as well which again is important.
regular is $4/gal were i live and the 300-6 just seems more practicle if you want to have fun this summer.
either way good luck with your build and keep us posted and take lots of pics

 

Well I called the gut about the 400. And he didn't know much of anything so I might just go with a 302 or a 351W that I've hurd that can bolt right up to the bellhousing I have now that came with my 300.
I found out that I can't rebuilt my 300 thought cuz on the number 2 cylender wall had 2 cracks running doen the entire leanth of the wall going all the way through too the water jacket.
I could get the 300 sleeved but then all of the labor, part, and making sure that there are no other cracks in the block would be a hell of a lot more then just getting another engine and dropoing it in there.

 

I personally feel like the 400 is more suited to a truck than the 302/351W. 400s do not need massive head work to make power they out flow any other small block ford head by a lot except the 4v clevevland, 400 heads are pretty much 2v cleveland heads they have 2.04 intake valves stock the exhausts are 1.6 something. The 400s problem is compression, it never had any. To get the compression up a set a australian heads and zero deck pistons from TMI can get you a detonation free 9.5 on pump gas with the right cam. These motors can but torque monsters if built by some one that knows what they are doing check out the 335 forum. Unless you go with aftermarket heads the 351W can't even come close to a 400s potential, although I will admit that the 351W does have a better selection of parts avalible. Unless you want to do a total rebuild a 400 isn't the motor for you, but rebuilding it to be a great motor doesn't cost that much more than a regular rebuild.
-Johnboy

 

I'll toast to that