box frame?

[black beauty]

my best friend who has an '90 bronco is fixing to do a 429 motor swap and is worried about the frame twisting under power(the frame is perfect though, no cracks and not rusted through. just typical surface rust). so his question is whether he should box his frame for the power of the motor. any advice you could give me to relate to him would be appreciated. keep in mind also this is going to be a somewhat daily driver/ show truck. no off roading at all. so to box or not to box?

 

[BB33's]

In my opinion the bronco frame would be strong enough to support a stock to mild 429 but why? Those are heavy motors and a 302 or 351 that came in the trucks can be built for up to 450hp cheaply and still make it a very reliable set. He can even keep the fuel injection :-& #036; If he is dead set on the swap L&L products makes a kit with all the neccessary parts.

 

[Broncobill78]

A few questions spring to mind. Why a 429 ? Does he have one just lying around and wants to use it ? The 31 extra cubes of the 460 are a nice bonus AND you can find 460's all over the place whereas the 429's are a vanishing breed and on top of that finding an injected 460 is easy and that would be a BIG advantage in a daily driver with fuel prices being what they are. I know a lot of guys just like being able to say it's a 429 under the hood because of the association with Cobras, Boss 429 mustangs & the whole high HP racing history but at some point practicality rears it's ugly head. Is he planning to tow with it ? Because if it's a daily driver not to be shown, run in competition or played with off-road then why in the world would he do this ? And if he IS going to tow with it we're back at the 460 being the much more practical option because of the extra torque and the ease of finding a complete multiport EFI engine.

Now having gotten all those questions out of the way I thought an answer to the actual question would be a really nifty way to close out the post. For a strict daily driver no I wouldn't bother to box the frame. I've done a few of these swaps and the built-up engines that I ran off-road and in competition, sure I boxed those frames Once I started getting up above 400hp it was simply the smart thing to do and the frames held up rock-solid. On the other hand the mildly built daily drivers & trail rigs never had any problems with the original unboxed frame sections. Of course it certainly won't hurt anything to 25" or 30" of 1/4" plate onto each side with the engine frame mount in the middle. It's cheap insurance but certainly not anything that should ever be needed

 

[Justshootme84]

I don't see the need to fully box the entire frame just for the 429/460 swap. The area around the engine crossmember is already "boxed" or re-inforced from the factory. A couple areas I did box on the 84 Bronco frame were the frame horns for the SAS and where the outriggers for the rollcage attach to the frame. I would consider adding a short piece of chain on the left/driver's engine mount to keep from tearing it up from the added torque of the 429/460. You'll need to use the L&L swap mounts or equivalent, or swap to 460 frame stanchions to use the 460 mounts. JSM84

 

[black beauty]

so i checked out l&l products sight and i saw just the motor mounts for a 429/460 motor. their in the neighborhood of $125-$130.00. they have a whole conversion kit thats $1,200-$2,700. so im hoping its just the $125 motor mounts right?

 

[Justshootme84]

Yes, the motor mounts are only about $130, you can buy them from Jeff's Bronco Graveyard. I bought mine from JBG, too. You (or your friend) need to run headers with the L&L mounts to qualify for their warranty. The rest of the L&L conversion kit includes brackets for relocating accessory drives like the alternator, ps pump, etc. Their headers run about $550-$600, but are a good quality product, JSM84

 

[black beauty]

so your kit that you purchased ran you about how much in $$$$?

 

[Justshootme84]

I bought the motor mounts for $120 from JBG, and a used set of the L&L headers for $150. I did not need to buy any brackets for the 460, since it came from an 88 F-350 and had everything on it. One last thing. IF the donor 429/460 has a front-sump oil pan, it will need to be changed to a rear-sump to fit in the Bronco. JSM84

 

[Broncobill78]

so your kit that you purchased ran you about how much in $$$$?

The last L&L kit I bought was more than 10yrs ago and back then I think it ran about $900 for the complete package. You *can* get by with just the L&L motor mounts but if you want a *hassle-free* instalation you'll get the entire kit. I've done four 460 swaps now, 2 on 78/79 Broncos of my own and a couple others with/for friends one was a 79' Bronco & the other was a 77' F150. You can swap the 460 in using all Ford parts if you want but if you go that route you'll need the 460 frame mounts as well as the 460 motor mounts, all of the correct bracketry from a 460 and you'll have to use the stock 460 exhaust manifolds. Now you can try and do it cheap by "modifying" the 302/351W/351M/400 brackets to the 460 but it'll be a nightmare & look like the Truck that Jack built when you're done and there will be no end of hassles trying to line up the V-belts and make everything work. Don't try and do a partial-deal either, using *some* Ford parts & *some* L&L parts, this is also a recipe for a stroke for pretty much the same reasons. While the L&L kit isn't cheap is is most definately money well spent. The L&L motor mounts fit the stock frame mounts and will work *best* with L&L headers. If for some reason you decide to go with manifolds make SURE you get/use the truck manifolds whick exit angled down and at the very rear instead of the car manifolds which exit straight down about 3/4 of the way back. L&L is really a great company. The second time I bought their entire kit I tried to save a few bux by buying their blemished chrome headers, the ones they sent me had the ****** ground incorrectly and even after notching the passenger side frame mount they were knocking on the frame at idle and driving me crazy. I sent them back & they reground & returned them but the problem was still there. I returned them a second time and after regrinding them again they misplaced them. At this point I'd been without wheels for close to 4wks all-together because of it and and as an apology they sent me a set of the stainless headers which fit like a glove. They could have hosed me & made me wait or told me it was my own fault for cheaping out in the first place but the cust service guy was right up-front about everything and they sent me a set of headers worth $500 more than what I'd originally spent. All the recent carb vs. EFI debates have gotten me thinking about a nice multiport 460 and I've started kicking around the idea of doing a 5th swap.

To get back to the original post, you're definately best off going for the whole package if you want a minimum-hassle swap. The L&L motor mounts, headers & bracketry combo is really the way to go. If you're feeling adventurous and want/need to do it cheaper then I'd go with the L&L motor mounts & headers and adapt away with the brackets. JSM is right about the rear-sump oil pan but you can score one of those from a mid/late 70's Econoline van w/the 460, that's what the Ford part # on the pan L&L sent me tracked back to. There's no shortage of guys out there who've done this swap by doing nothing more than scouring the local junkyards for the parts and it'll work just fine if you choose to do it that way, you simply need to decide how valuable your time is and how much time you want to spend dicking around with the little bull$hit aspects of the swap (like grinding out & clearancing the mounting holes for the PS pump bracket or figuring out how many washers need to need to be behind the upper right-hand bolt of bracket X so it lines up with pulley Y).