250 motor

[Midgets50]

so ive been looking for a 250 inline 6 to put in my truck. what all did these motors come in and how hard is it to find them?

[Wrenchbender Ret]

They came in many 66 up cars & trucks. After 1975 the trucks started useing an intregal head model. Stay away from it.
It seems they are all over the parts for sale sections of the old truck websites.

[NEWFISHER]

I have a 76 model with H.E.I. and it performs well unless I tow our 3,000 lb trailer up a hill and then the 3:08s and the sm 420 suck eggs. I'm sticking with the 250 and have sourced a newer 3:73 rear along with a 700r4 that's ready to go in as this Winters project. Should make the 250 happier pulling a load.
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[Midgets50]

thanks guy i have a turbo 350 im planning to put behind one and 3.73 gears in the new rear end i have for it

[lmdangerous]

Just finished a mild 250/2004r swap in my 51 3800. It is sweet 60 to 65 no problems,even with a 4:10 gear .Lots more left in it , and the milage is a lot nicer than the 235 and SM420 I had . Lots better

[Midgets50]

Originally Posted by lmdangerous

Just finished a mild 250/2004r swap in my 51 3800. It is sweet 60 to 65 no problems,even with a 4:10 gear .Lots more left in it , and the milage is a lot nicer than the 235 and SM420 I had . Lots better

what are you getting for mileage? thats a main reason why im trying to get rid of my 235, that and my turbo 350 wont bolt up to it without the adapter plate. just to clarify, but cant the turbo 350 bolt right up the the 250 with no problems or adapters?

[mknittle]

Any time you use an automatic trans mission you lose fuel mileage.there is just more drag in planatary gears.

[NEWFISHER]

yes, 350 will bolt up. If you are going that far, swapping engine and trans, why not a 700r4 and be done!


"Any time you use an automatic trans mission you lose fuel mileage.there is just more drag in planatary gears. "

Yes, Unless the engine is smaller displacement and the gearing is too low in a heavy rig, working the engine harder at desired speeds. Like a 235 and an old 4 speed truck trans

I had helped with a 235 in a 55 car, Buffalo adapter to a 200r4 (same rear diff) and milage improved over the 2 speed powergilde. Completely different vehicle , but similar example

[lmdangerous]

Around 18 mpg so far. And it will actually pass something and not act like its gonna die. I am looking at the turbo thread from the 60-66 thread . That looks intresting as well.
LMD

[Midgets50]

Originally Posted by NEWFISHER

yes, 350 will bolt up. If you are going that far, swapping engine and trans, why not a 700r4 and be done!


"Any time you use an automatic trans mission you lose fuel mileage.there is just more drag in planatary gears. "

Yes, Unless the engine is smaller displacement and the gearing is too low in a heavy rig, working the engine harder at desired speeds. Like a 235 and an old 4 speed truck trans

I had helped with a 235 in a 55 car, Buffalo adapter to a 200r4 (same rear diff) and milage improved over the 2 speed powergilde. Completely different vehicle , but similar example

the reason im using the turbo 350 tranny is because my truck is gonna be 4x4 and the turbo 350 seems like a good 4x4 tranny. but i also dont know much about trannys, if you have a better suggestions im always open to new ideas

[NEWFISHER]

Perfect for 4x. Makes a shorter combo and you can double the 205 with a 203 for lower tcase gearing and have a longer front driveshaft for a better angle if you are lifting it. If its stock hieght and not going crazy with big tires etc then a 700r4 would work and give you better highway gearing.
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[1project2many]

As pointed out above, any transmission which prevents the engine from operating at it's most efficient point for the longest time is wasting energy. In that case swapping to a less efficient trans can make for a more efficient vehicle.

If you end up choosing a 250 or even fall into a 292 you might want to consider the powertrain as a whole. The 250 has a similar bore and stroke to the 305 but is more limited in airflow so it's not the greatest for mid range power. A towing or RV cam is a good way to shift the power curve toward the lower rpm ranges. I think the 3.73 isn't a bad choice for a rear gear but if you're carrying a large load or moving a big truck / big tires you might want to get a torque converter with a high torque multiplication ratio to help the engine at low rpm. Some of the diesel converters have very high multiplication ratios along with low stall speeds but there are also specialists that build whatever you want. The 700R4 actually has a really steep 1st gear ratio which can be helpful for offroad or towing but there are other ways to add gearing if needed and the THM350's a decent, reliable trans.

[Midgets50]

Thanks guys always appreciate the wealth of knowledge you guys share. id be lost without it on my build

[Midgets50]

Originally Posted by NEWFISHER

Perfect for 4x. Makes a shorter combo and you can double the 205 with a 203 for lower tcase gearing and have a longer front driveshaft for a better angle if you are lifting it. If its stock hieght and not going crazy with big tires etc then a 700r4 would work and give you better highway gearing.
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Im not sure about lifting it but i want to put bigger tires on it. and i am unsure of the transfer case because i have never seen a all time 4x4 transfer case and my tranny just happens to have one currently. on the shifter before i took it out of the cab it went 4 hi lock, 4 hi, N, 4 low, 4 low lock. this is new to me