i have a 1981 f100 with a 302 3 on the tree in it now. i am looking to put a 460 big block and a 5 or 6 speed tranny in it. i would like to know what kind of a challenge i am up against. and i need a wiring harness for it. if anyones got any tips please let me know.

 

You'll need different engine perches. A 460 ZF5 out of a later model truck would be a good tranny as it'll stand up to the 460 and gives you overdrive to boot. But, I'm guessing you'll want to change the rear axle ratio because many of the F100's were geared for economy with something like a 3.00 diff. Something like a 3.50 would be better as it would allow you to use the OD frequently where a 3.00 wouldn't.

But, your F100 probably has the 4 1/2" bolt pattern and you'll have light duty suspension. So, you may want to change that. And, you'll almost certainly need heavier front springs.

You'll be money ahead to find a donor truck with the 460 and a manual tranny so you can get everything you need from it with the exception of the ZF5. And, expect to pay ~$500 for the ZF5.

 

The F100 has got smaller brakes, too.

 

ok so i got to get diffrent engine mouts and then the 460 well bolt right in? and where is a good place to look for the parts? thanks

 

Not motor mounts...perches. This is what the motor/engine mounts bolt to in the frame.

there is a lot to do in this conversion.

Gary is correct, as always, on the rear. My f100 has the smaller bolt pattern (car) axles with a 2.75 gear. Still a 9" rear so handles the 460 no problem. If you want a lower gear, which is probably a good idea with a ZF5, then you have a couple options. 1) swap the gears 2) get a different rear end. If you swap the rear end, you will also want to swap the axles from your current 9", You don't want different bolt patterns on the front and rear. They have the smaller bolt pattern but from my understanding they are interchangeable.

The frame for the 460's also have a cutout in the engine cross member for the oil filter to sit in...otherwise it will hit the crossmember. Some run a remote oil filter kit to get around this. Mine has a crosse member swapped out.

You will need a larger radiator

Wiring shouldn't be an issue if you get a 460 from the same vintage. My F100 had the 300 and used all the stock wiring for the 460. converted the distributor to the DSII that was on the original 300.

Springs did not change and seem to be fine surprisingly.

Like Gary says...if you have a donor truck....it will all simply swap over. Well, not simply but it will.

 

No, not just mounts, PERCHES. The perch is the metal bracket that attaches to the frame & crossmember, and to which the mounts attach. You may need different mounts themselves, but that's easy.

I don't know how the perches are attached on your '81, nor how they are attached on something with a 460. But, the ones for the 351W on my '82 were bolted on the passenger side and both bolted and riveted on the driver's side. There were 6 rivets and they were TIGHT. I had to use a carbide burr in a die grinder to take the heads off, and then drive them out with a hammer and punch. It was a lot of work at my shop where I have a few tools (to say the least), and would be very difficult at a salvage.

So, where is a good place to look for parts? The best place is in the parts truck you buy. Second best is at the salvage, but you will make many trips 'cause you'll either forget several things or they won't be on the truck(s) they have.

To try to make my point about buying a parts truck a bit more obvious, here are just some of the parts you will need:

• Engine
• Perches
• Exhaust manifolds
• Exhaust pipes
• Clutch, flywheel, & pressure plate
• Front springs
• Radiator
• Shroud
• Differential
• Transmission tunnel cover

On top of that, if you are going to use the truck as a truck or drive fast you really need to upgrade the wheels, spindles, rear axles, rear springs, and brakes. But, all of the above and these upgrade items would be available from the right parts truck.

Edit: Kevin, we seem to think, and type, alike. PERCHES! LOL Hope we got his attention, and he wasn't paying close attention before. And, sorry, but I can't rep you although I would like to - especially for the crossmember alert. Gotta spread the love.

 

A 1981 will have a mechanical clutch linkage and the ZF5 uses a hydraulic one.

Probably a different-length driveshaft, too.

 

Well I take that as a compliment Gary I consider myself Rep'd

 

Well, the small-block version of the ZF has a dedicated hydraulic linkage, meaning that it can't be easily turned into a mechanical linkage. But, the 460 version can easily be used with a mechanical linkage, which is how I plan to use mine. That side-steps the problems associated with a hydraulic master cylinder causing cracking on the firewall.

 

Attached are pictures of what these guys are calling "perches" (green arrows).

The red arrows point to bolts, the yellow circles depict cigar-sized rivets holding them to the cross member (I don't remember exactly how many exist).

Pictures are of a 1980-82 Bronco that had an M-block in it.

Yes, the cross member will need to be dealt with to accommodate a 460, too.

 

I guess I can add a little to this.

Once you have the old perches ground off, it's basically a bolt-in install. A 4.5" angle grinder with a course flap wheel does a good job to get the heads off the rivets, then punch them through. The perches you need have two slots in each one instead of one for the motor mount studs.

If you plan on using headers, order up some for a '85 F-250 or there abouts. I had them in mine and they fit good. Only complaint is the left collector is a little close to the trans.

One thing to do is check your rear wheel bearings. If it was used as a truck, they'll probably need replacing. They will be the non-tapered style with the seal pressed in the tube instead of on the axle between the flange and bearing. Oh, and they will still be 31 spline axles.

For the oil filter, either get the 90 degree adapter off a parts truck or run a remote system.

The stock springs will handle the extra weight if they are in good shape.

May want to look for a different column too, if you want to get rid of the shifter on it.

And as mentioned before, radiator, hoses, driveshaft, and various others. You won't get it all in the first trip.

If you have all the parts, it should only take a couple of weekends of work to do.
One more thing, pull the core support when you put that beast in. It's kind of scary having a 460 and trans that high while trying to put it in, and you can leave the hood on then.

 

ok so. i scrapped the switch to a manual transmission, so i got the 460. and L&L products is a company that makes motor mounts and they say that you don't need to change the perches. as long as it had the small blocks in it and not the inline 6's. and well i have to change the tranny cross member oor change out the drive shafts?

 

so i have to change the perches and the oil filter location or angle and what would you guys sugest as a tranny to run in this, i got the tranny they mainly used other then the c6 with the motor just woundering if i should send it out to be rebuilt and beefed up or just go a diffrent route?

 

Not sure what you mean by "I go the tranny they mainly used other then the C6"? I woud say the C6 was probably the most commonly used tranny for the 460 in this era.

C6 is a strong tranny and can hold up to most 460's, even with a little build to it. It is straight forward and simply yet tough.

You can go with an OD Auto but that gets more complicated...unless that's what came with your motor.

What did this motor come out of? What year is it? What tranny is currently bolted to it?

 

the motor came out of a 1977 f-150. it's not the c6 its the other one i am led to believe. what other trannys were there back then if you list them i can prolly tell you the name.