1966 f100 side step prerunner 351w swap to 250 new project

Got this heavily fabricated truck with 1970 ford I beams and disk brakes, long travel race tec 20 inch travel shocks, 9 inch trussed housings. Custom national leaf springs very stiff and has a 1975 351w and c4.

Professionally cages and has some auto motive buero sticker near door Vin for a certified swap.


Obviously plan to yank the complete v8 and it's still light enough I think the ford six will make it that much more agile on all terrain. It should be hot as I want to do a hi stall 2400 plus to get the tires going If intake it to the sand.

I think it will be ideal just concerned about header options and I think the only main part I'm missing is the flex plate and torque converter.

First time getting a 250 installed so are any of the parts usable from the 351w....mainly need direction on getting the right torque converter, flex plate and starter...
Header maybe a whole mother sorry since it's caged around the engine bay.

Any thoughts?

Plan to use a 69 250 with a small log head, some of the Oz silvolite pistons not sure what size I will need since the head is 54cc with adjustable rocker, oversized ss valves and dual springs, plan to use a adapted 480 CFM autolite four barrel.

Like to stay around 9 to 1 compression ratio as it could see hot dessert days. Mainly hoping this will lightness the front alot over the 351 and handle better in the corners or landing if it gets air born.

So do I have options or can I buy the flex plate though local auto suppliers and torque converter...this should bolt right up instead of the 351w....any thoughts or input as I want to get this engine built up rather then the v8.

i think you would be better off building a 240/300 big six instead of the 250 small six, imo. flatter torque curve, and better power production. and you get the removable intake so you can put on what ever carb you wish.

I know the 250 can use the bellhousing/flexplate/torque converter from a 302, but I don't know about the 351W.
The 351W is a tall deck 302, so it might.

I agree with rbohm, a 300 big six (not 240) would be better.

Of course if a 250 is available and a 300 isn't, then the decision is made.

Have fun.

rocklord":3l88eyzf said:

I know the 250 can use the bellhousing/flexplate/torque converter from a 302, but I don't know about the 351W.
The 351W is a tall deck 302, so it might.

I agree with rbohm, a 300 big six (not 240) would be better.

Of course if a 250 is available and a 300 isn't, then the decision is made.

Have fun.

Click to expand...

the 250, 240/300, 302, and 351w all use the same bell housing, and the flexplates/flywheels all use teh same bolt pattern. the sixes all use a zero balance flexplate/flywheel.

Hi rbohm.IIRC,the Cleveland blocks also use the small block bell patterns.
Good luck.Have fun.Be safe.
Leo

woodbutcher":1adscike said:

Hi rbohm.IIRC,the Cleveland blocks also use the small block bell patterns.
Good luck.Have fun.Be safe.
Leo

Click to expand...

very true leo.

Okay so if I can use the 351w flex plate and torque converter then I'm leaning toward the swap even though I'm sure power difference is considerable from the mild 351 in there ....especially if I swap for the performance alloy heads....time to sell the Windsor and pull it this week so I can get some pictures up of the fresh 250 block in there

I did a efi swap on a 87 f150 so I actually just let that block go...that actually would have been a great combo but I do like the idea of the c9 250 being in the same decade of parts as the car.

Pictures and progress to come!

autoX65":2vuaq287 said:

Okay so if I can use the 351w flex plate and torque converter then I'm leaning toward the swap even though I'm sure power difference is considerable from the mild 351 in there ....especially if I swap for the performance alloy heads....time to sell the Windsor and pull it this week so I can get some pictures up of the fresh 250 block in there

I did a efi swap on a 87 f150 so I actually just let that block go...that actually would have been a great combo but I do like the idea of the c9 250 being in the same decade of parts as the car.

Pictures and progress to come!

Click to expand...

you can use the 351w flexplate, but you will have to have it zero balanced.

Okay zero balance got it so I will have to get a zero balance flywheel. I will get some pictures on my photo bucket and put the link in here to see what I'm working with. ..its a clean low rust truck for the age so not to concerned about body work I can handle that..

Plan to wrap the fiberglass to look like carbon fiber and thinking a metallic violet real light mixed with white. For the can and bed then por 15 the roll cage...

I'm sure Glamis or the dunes would be fun this labor day weekend!!

Well I know I'm will depend on gearing but should n I be able to get the tires going in the sand with 33s as I'm sure I'll be in the 4:10 range ideally. ...have to get a locker in there still.

And last if I get the zero ballance flex plate can I use the same torque converter or do I need a actual 250 application?

first you dont need to get a zero balance flexplate. take a look t the one you have now, and locate the balance weight that is welded on. just have a machine shop remove that weight and you have a zero balance flexplate.

as for the torque converter, it should work fine.

where R U? down under or 'here'?
if 'pre-runner' no need 4 speed,

No west coast not down under. My transmission guy builds lots of trophy truck c4 transmissions that have completed Baja 1000 type races...its far from anything but class 8 stock type width Baja racing but I don't plan to do anything like that.

"...class 8 stock type width Baja racing…"
Yeah, the sports ute is gettin closer to the trophy trk these last few yrs. Got a friend who uses 1 of Parnelli Jones orig truck to pre run 4 a crew @ Baja. And if familiar w/the bronk vendors - Chuck A. started a 'classic' grp to run there…
8-0
All way, way beyond ME!
Love yer step side. Used 1 (same yr) on a brood farm for everything. Even carried a blower on frnt when the sno got really deep! Wish it had the 250/300 as the bent8 couldn't lug in the low revs like they can. The tq seemed 2 B in the higher revs…but it's been 30 + yrs ago.

Just read the post higher up, nother thought…
U might like the C4 better too?
Less parasitic of the power, lighter
(U stated that interest) and ur friends can build it right!

http://s1292.photobucket.com/user/autoX ... ent&page=1

Here are some photobucket pictures..

The 351w seems decent condition ...at least it turns. Plugs look great, now water down manifold and is relatively clean...

I plan to stay with the c4. I always run those in most all my hobby cars...ya I know class 8 is very competitive and it would take a whole revamp on all suspension geometry. .

It is a big truck with the back sitting 3 or 4 inches higher then the rear and I like that look over the front jacked up.

The tires and rims make a big difference snd don't have the front end all assembled yet but had a aggressive look with the front hood on...

I'd say this coming weekend I'll get the race tec coil over shocks on and hook up thr steering and it has a few steering box options. Have a rear disk brake kit to hook up this week.

And comparing what is in there now since it the Windsor has stock exhaust manifold just cam performer intake and 600 holley...it may only be at the same range as what the 250 built would be maybe 200 hp so I guess the only thing is the timing chain draw back on the 250.

What silvolite oz piston 255 hasting piston can I go with on the 250 and say a 54cc combustion chamber head?

I tried some spray on evapo rust and it works wonders in minutes for surface rust with steel wool...basically got the entire car clean minus the roll bars I'll have to remove that section since it's bolt in for the rear part and the front and cab and engine bay is all welded to the frame.

Also did lube up the 351 with a mixture of marvel mystery oil and gas in the cylinders and it feels perfect by hand cranking. I'm sure it's a perfect motor...going to put some fresh oil in it just so I can sell it as a runner....I have it listed at 475 and had some interest but every one wants to hear it run....I thought it's a great deal at that price with known history and being good and not froze.....picky bent 8 guys ehh!! Going to test the alternator, starter and freshen up the holley on it so I can get a buyer. Going to start putting some pricing and parts lists together for the 250 swap, like need headers, ignition upgrades, ds2, gaskets, flexplate ect. ..

I can't wait to see the ford six nestled in that engine bay!

just getting the parts list ready for this to get it up and going.

Im planning for the 3332h silvolite 12.86cc dish australian 4.1 pistons,
large log head, adapter and 2v and pretty much have to go with stock exhaust manifold in hopes to get a header from clifford as a later upgrade.

should be putting a final order to do assembly on the 250 around next week and get it in there by middle October would be ideal.
got to do some parts order and gathering so ill see what I can get my hands on over the next week or two.

"...I have it listed at 475 and had some interest but every one wants to hear it run....I thought it's a great deal at that price with known history and being good and not froze…."
could U make up a stand to show them / run it on?

I'm surprised U don't use the 300/4.9 in that white '78/9 bronk. There's some brothers who run one in the off rd. competitions (I think they're from Michigan?) and have a long string of wins over many years.

Just had actually got the motor running...did put 200 bucks to refresh it with new valve train.

Got 550 so technically only made 350 for a good 351w ...guy got a great deal who picked it up and I loaded it and removed it for him.

Just detailing the engine bay got all my Paint supplies for that this week...and doing some rest fits for the 250. And modifying the mounts for engine...and transmission. As I want it pushed all the way toward the driver side as possible to make room for exhaust.

I'll get a picture up this weekend of the engine mounted in there.

Got a new set of strange 4.71 gears for the 9 inch to start...plan to get a tighe camshaft for this one....

Have stainless 1.75 intake and 1.46 exhaust..

Dual springs hardened locks and retainers and cut in valve seals.

Percision cylinder heads said 514 for the cylinder head work.

Got to order some of the silvolite dished 250 oz piston. And plan to custom mill the dish a few more cc.

I think they are 12cc and if I can get it to 16 that would be prime.

Plan to run the auto lite 4100 480cfm 4 barrel I have for this too.

Need advice for endurance prep I should do too the block ...

Amd still debating what route as I have a custom aluminum intake build on one head or just build a large log and direct mount one of those two top four barrel adaptors on it.