Questions about 250 cu in I6

O

OldesI6

New member
I have aspirations of restoring an Early Bronco and I am debating between in I6 and a small block V8. I am not so concerened about hp but definately want lots of torque. I know that I6s can make a lot of torque but can it be enough? My plans for my bronco is to build a LUBR (Lifted Uncut BRonco) and for it to be a daily driver capable of mild trail use, going up into the mountain for fly fishing trips. I am not all that concerned about price, I am not loaded but I want to build a strong engine. My last engine venture was a unique stroked Ford 400 making 434 cu in. Let me know what you think. I also know that a 250 will not work in a Bronco unless you have a suspension lift, which is what I plan, and the oil pan needs to be customized so it has a rear sump.

Thanks!
 
Depends on your ultimate Goal , a 250 is a great torque motor , BUT it ain't a 434 , geared right it will work great , as far trailer towing , the SHORT early Broncos are NOT a good Idea , a small utility trailer maybe , Just my experience
 
I like the idea, 250 bronco! sounds up my alley... my opinion might be biased* lol

the 250 is more low rev vs it's cousin 200, longer piston travel, longer rods, I take my mustang on many dirt trails, some I should I shouldn't but it comes thorugh the same, I really like stick shift...

is your LUBR to be 4x4? If so you'll have a lot to do, the engine is alot longer than a v8, and long enough to runa an electric fan instead of the 200 with a mech (but that helps performance) but with 4x4 it can be done and would be very unique :thumbup: (unlike them cookie cut'n v8's)

If you do go 250, I advice is to think it through, you'll want a torque beast, and teh SBF can do the same, but it's not... the torque on the 250 will stay with your entire rpm range vs the v8 it comes on little later compared (still lots of torque on both engines, just say'n the i6 is sooner where it's needed)

for tq, think 9.0-9.5 CR range, nothing higher other wise you'll start making hp and needing higher gas, for mpg only clean up the intake ports and put larger valves in there keeping the exhaust flowing 65-80% of what the intake flows (IIRC it's the best ratio for peak mpg) then get a single grind cam, the 250 can use alot because of the restricted head, so a 264/264 would be good, but I would recomend 274/274 for the extra cubes. you'll want vacuum so naturally 112.

with this you'll be close to gene's mavrik and if you went the extra route and got the 2bbl direct mounted a nice 350 or 500 holley would suit you well on any trail you take. the manual will give you more power so that is an option.

Good luck and keep us updated with any pics

*(at least I gave ya a warning)
 
The Bronco originally, for some years, had both the 170 I6 then eventually had a 200. While I like the 200, the 250 has more torque ability and I realize that an I6 will not make anywhere near what I had with my 434, it put out almost 560 ft lb torque but that is way more than I need in a DD and mild trail use. I do not have any plans of rock crawling at all.
 
I have had a 77 Maverick 250 for a long time (is almost all stock), it pulls as good or better than most SBF V8's from a stop. Only draw back is it dose run out of pull at freeway speeds. I think you would like a 250 in the Bronco they are lighter too.
 
You will probably be very happy with a 250 and a NV3550. My current 250 is a 1970 mustang motor, stock, that the previous owner had a valve job done right before I bought it but I could not determine if they milled the head enough to compensate for the thicker gasket. So it may be lower compression than what was stock for that year. Even so it performs very well with the NV3550 trans which is a vast improvement over the old three speed. Good acceleration, mountain passes no problem and very relaxed cruising on the highway with the od fifth. I started with the original 170/3 speed went to the 200 and now the 250 and am very satisfied. Lots of torque. 4:11 ratio and 30" tires currently. Mine is a daily driver type use, dirt roads, no extreme off roading or rock crawling.
 
Not yet. There is a guy on classicbroncos.com that has done his and has indicated he could provide pictures and details. I have his forum name somewhere. I have not had any problems with the mild off roading mine does.
 
68broncoPaul is the member on classicbroncos.com with the 250 pan mod and has pictures of the process. He is doing an upgrade on his fuel injected 250, going to multiport, pretty talented Bronco owner.
 
This thread got my interest in the Oil Pan mod discussion. (I have no off road or BBF V8 experience). I run a mod'd 250 in a '61 and am interested in building a Fox Body Mustang with a similar 250 Six setup. The Fox Body 'Stangs used the 200 @ 79-82 with rear sump pan I was told. ( 'never found an L6 Foxbody). 250 oil pans are wider as you know so it would need fabbn'. The mod'd 250 is a different animal than most performance engines. Not unlike early big block V8's, torque curve starts at low RPM and sustains (until RPM's become dangerous 8) ) . With OD tranny and 3:80 rear can cruise interstate effortlessly at low RPM/ OK MPG. Attention to breathing and gearing for your application can yield a useful - easy to maintain and afford combination.



250 oil pan

 
Not trying to hijack the thread but OldesI6 may be curious as well to the details on your 250. Are those Hooker headers? I have been looking for some long tube headers for mine.
 
Along with my triple carb adaptors and Explorer/Bronco/Mustang IRS swaps, I've got a rail adaptor kit which converts 250 engines to the US Fox body oil pan/sump.

It's just the width of the sump and the diameter of the main and crank snout seal that differ, and the fact that early US sixes were not cast for the later Fox body rear dip stick mount.

US 200 blocks after 1978, and Aussie 200 cube I6 blocks from 1972 to 1985 were cast with the later model rear dipstick, and the Cortina sump from 1972 to 1983 and Australian 1976-1985 F100 250 sump fits the Fox and Bronco.
 
I have contacted Paul from the classic bronco website but have not heard from him yet. Those headers look sweet Powerband! I was looking around for a 250 engine and found a xflow one from hotsixes for $595 but it would probably be a fortune to ship to the US. I'll keep researching and see what I come up with. I read an article today from an old bronco driver magazine about a guy who put a 300 in his Bronco! A lot of mods but it looks nice!
 
For those that asked:

There were Headers made for the 250- Hooker 6602's. Application was Maverick 250. The more common 144/170/200 Hooker 6601 dual out - long tube headers won't fit the 250 without modification. The headers hug the bell to clear the starter and with the larger VeeAte/250 sized bell, the 200 6601's interfere. MAny current single and dual out headers claim to fit both 200 and 250 applications but the taller deck height AND low mount starter AND larger bell 250 cause problem interference. The Hooker Super Competition' port flange has 6602 stamped between 2/3.


 
I tried looking up the headers for Maverick, was there a certain year because I could not find them? Explored...was that a stock 250 oil pan and what year 250 engine did you put in your Bronco?
 
Engine does just fine. No dyno anywhere close, but three different desktop dyno's put it right at 200hp@4800rpm and 250ft.lbs torque@2800rpm so allow for error.
 
OldesI6":4oy8n0oz said:
did you modfy your oil pan for a rear sump?
Click to expand...

some do some don't. If yer concerned bout 'starvation' I would B more concerned with fuel. Make sure to put in a carb that can take the gradients.

Also - x-flow is for HP not tq, (I seek tq...)
 
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