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1967 - 1972 F-100 & Larger F-Series Trucks Discuss the Bumpsides Ford Truck

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Old Sep 21, 2015 | 12:55 PM
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Engine swap

I have a 1972 F250 with a 428. I would like to find out the ins and outs - pros and cons of dropping the 428 and putting in a 300 six.


First, would I need to get a totally different C6 tranny or could I use the same one?


Would the shift linkage be the same? ( It's a column shift )


Is it worth it from fuel economy standpoint?




C6 question: Are all C6's geared the same?
 
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Old Sep 21, 2015 | 01:00 PM
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Different tranny required due to different bell pattern. A 300 uses the SBF pattern and the FE pattern is FE-specific.


Shift linkage slightly different due to... a different tranny. Btw, all automatics were column shifted unless someone modified it to be on the floor.


Mileage will likely improve with a 300. But power will be the "cost".


Dunno about gearing but I figure C6 gearing differs depending on the application.
 
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Old Sep 21, 2015 | 01:18 PM
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C-6 has the same gear ratios as a C-4. 2.46 1st, 1.46 2nd, 1.00:1 3rd.

An AOD and AODE have ratios of 2.40 1st, 1.46 2nd, 1.00:1 3rd, .67:1 4th (overdrive).

4R70W ratios are 2.84 1st, 1.55 2nd, 1.00:1 3rd, .70:1 4th (overdrive).
 
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Old Sep 21, 2015 | 01:42 PM
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Thank you HIO Silver.


I had a 65 F100 back in the late 80's that I swapped out a 300 six for a 390. The 390 I bought had a automatic tranny attached which I didn't use because the truck had a NP435. I don't remember ever buying a bell housing for the swap. Could the automatic that came with the 390 have had a removable bell housing that would have mated the engine/ NP435? I know the tranny wasn't a C6.


Just one of those odd questions that bug me. I would have thought I'd remember buying a bell housing.


My memory is of how easy it was to swap as everything lined up from engine to drive shaft. I do remember having to move the motor mounts but that was about it.


Any insights? or am I just senile?
 
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Old Sep 21, 2015 | 03:24 PM
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I don't believe the C6 has a removable bellhousing. One thing to note with a C6 is that it is a heavy duty trans that robs a lot of power. One behind a 300 I6 might be a bit of a dog. That might negate quite a bit of your fuel economy gains by going to the I6. If fuel economy is your concern, you might want to switch to a C4 or take the plunge on a manual swap with the I6.
 
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Old Sep 21, 2015 | 04:42 PM
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Originally Posted by 72CC428
Any insights? or am I just senile?
Hmmmm, Let's just say your forgetter is kicked in. The C6 is a 1 piece case, so you would have had to get a FE bell.

The 428 is the largest FE built, many here would think long and hard before giving up the big FE bull.

If economy is your main concern I would look at a much newer engine/OD tranny to swap in.


John
 
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Old Sep 21, 2015 | 07:24 PM
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Just out of curiosity, is it really a 428 FE with a C6 or is it a 429 385 series with a C6? Not very often do we hear a 428. But 429/460 been swapped a bunch in the past. Including my own. 2X John. If I had a 428 I wouldn't give it up.
 
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Old Sep 22, 2015 | 06:07 AM
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428

Yeah it's a real 428 FE block. I'm guessing it came out of a Galaxy or another big Ford car. It is dated to 68'. I love having it but I don't like watching the gas gauge move when I start it up! It is a gasoholic.
 
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Old Sep 22, 2015 | 06:11 AM
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QUOTE=Lneidlinger;15660450]. If fuel economy is your concern, you might want to switch to a C4 or take the plunge on a manual swap with the I6.[/QUOTE]


What are the pros and cons to a C4?
 
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Old Sep 22, 2015 | 06:19 AM
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Originally Posted by 72CC428
Originally Posted by Lneidlinger
. If fuel economy is your concern, you might want to switch to a C4 or take the plunge on a manual swap with the I6.

What are the pros and cons to a C4?
C4 is lighter and doesn't rob nearly as much power as the C6, but is still quite a stout transmission. They came in F100's so it should not much of a trick to drop one in.
 
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Old Sep 22, 2015 | 06:23 AM
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F250

Originally Posted by 72CC428
I have a 1972 F250 with a 428. I would like to find out the ins and outs - pros and cons of dropping the 428 and putting in a 300 six.


First, would I need to get a totally different C6 tranny or could I use the same one?


Would the shift linkage be the same? ( It's a column shift )


Is it worth it from fuel economy standpoint?




C6 question: Are all C6's geared the same?

The Rear gears are 3.73 It loves to drive around 40-55 mph. It really starts howling after 65mph. I mean rpm wise. Does that sound right for the tranny/rear combo?


I wish they had an OD tranny I could drop in that was easy on the wallet.
 
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Old Sep 22, 2015 | 06:26 AM
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Originally Posted by Lneidlinger
C4 is lighter and doesn't rob nearly as much power as the C6, but is still quite a stout transmission. They came in F100's so it should not much of a trick to drop one in.
What am I looking at regarding cost for a C4?


The linkage would change as well?
 
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Old Sep 22, 2015 | 06:59 AM
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Save your $ and get a Gear Venders OD. The best of both worlds. It would take a long long long time to recover the cost of any swap.
 
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Old Sep 22, 2015 | 02:32 PM
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Originally Posted by Alex from GA
Save your $ and get a Gear Venders OD. The best of both worlds. It would take a long long long time to recover the cost of any swap.
2X Alex. In the mean time I'd give it a COMPLETE tune up. Pertronix. Hotter coil. And play with the jetting in the carb. Bumps weren't meant for any gas mileage. "All you can do is all you can do".
 
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Old Sep 22, 2015 | 02:50 PM
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C6: The converter housing is made as part of the transmission case. Bell housings only used with M/T's.

C4's were not installed with FE engines in any car or truck.

C4: 1965/74 F100/250 240/300 I-6 / 1965/72 F350 240 I-6 / 1969/79 F100 302 / 1975/79 F100/250 300 I-6 / 1975/79 F150 300 I-6 & 302.

C6 optional in 1978/79 F100/250 300 I-6/302.

Personally, I don't see any advantage swapping a 428 for a 300 to improve MPG

These trucks have the aerodynamics of a brick, 105 octane gas was about 35 cents a gallon back then and no one gave a hoot about MPG
 
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